WEBVTT 00:00:00.000 --> 00:00:01.973 align:middle line:90% [SQUEAKING] 00:00:01.973 --> 00:00:03.446 align:middle line:90% [RUSTLING] 00:00:03.446 --> 00:00:07.374 align:middle line:90% [CLICKING] 00:00:07.374 --> 00:00:11.320 align:middle line:90% 00:00:11.320 --> 00:00:12.460 align:middle line:90% PETER HOUK: I'm Peter. 00:00:12.460 --> 00:00:13.220 align:middle line:90% I'm Peter Houk. 00:00:13.220 --> 00:00:16.520 align:middle line:84% I'm the program director for the MIT Glass Lab. 00:00:16.520 --> 00:00:18.480 align:middle line:84% We're part, of course 3, Material Science 00:00:18.480 --> 00:00:20.200 align:middle line:90% and Engineering. 00:00:20.200 --> 00:00:21.733 align:middle line:90% And this is Mariel over here. 00:00:21.733 --> 00:00:22.400 align:middle line:90% MARIEL BASS: Hi. 00:00:22.400 --> 00:00:25.040 align:middle line:84% PETER HOUK: Mariel is one of the other senior instructors 00:00:25.040 --> 00:00:25.635 align:middle line:90% in the lab. 00:00:25.635 --> 00:00:26.760 align:middle line:90% MARIEL BASS: Meet you guys. 00:00:26.760 --> 00:00:29.740 align:middle line:84% PETER HOUK: So we've done this demo a few times for JJ. 00:00:29.740 --> 00:00:34.280 align:middle line:84% And one of the things that we like to do is show you how-- 00:00:34.280 --> 00:00:37.160 align:middle line:84% to illustrate different coefficients of expansion 00:00:37.160 --> 00:00:38.400 align:middle line:90% that glass can have. 00:00:38.400 --> 00:00:41.000 align:middle line:84% So every single glass has a really different kind 00:00:41.000 --> 00:00:42.020 align:middle line:90% of formulation. 00:00:42.020 --> 00:00:44.360 align:middle line:84% Sometimes they're very close to each other 00:00:44.360 --> 00:00:48.060 align:middle line:84% in compatibility or thermal expansion coefficient. 00:00:48.060 --> 00:00:50.760 align:middle line:84% Sometimes they're really far away from each other, 00:00:50.760 --> 00:00:53.080 align:middle line:84% because I guess you know glass is a pretty 00:00:53.080 --> 00:00:56.040 align:middle line:90% big family of materials. 00:00:56.040 --> 00:01:00.240 align:middle line:84% Even though it's amorphous, it can be all kinds of things 00:01:00.240 --> 00:01:02.000 align:middle line:90% and have all kinds of uses. 00:01:02.000 --> 00:01:03.880 align:middle line:84% So two of the most common glasses 00:01:03.880 --> 00:01:06.920 align:middle line:84% are borosilicate glass, or Pyrex, 00:01:06.920 --> 00:01:08.985 align:middle line:90% that gets used in labware a lot. 00:01:08.985 --> 00:01:10.360 align:middle line:84% What we're going to illustrate is 00:01:10.360 --> 00:01:12.800 align:middle line:84% what happens when you put two glasses that 00:01:12.800 --> 00:01:15.200 align:middle line:84% have different compositions, and therefore, different 00:01:15.200 --> 00:01:19.440 align:middle line:84% coefficients of thermal expansion together-- 00:01:19.440 --> 00:01:20.840 align:middle line:90% what happens. 00:01:20.840 --> 00:01:24.080 align:middle line:84% And then after that, we'll do another demo 00:01:24.080 --> 00:01:27.680 align:middle line:84% about engineered stress in glass. 00:01:27.680 --> 00:01:30.000 align:middle line:84% And that includes glass tempering 00:01:30.000 --> 00:01:34.320 align:middle line:84% and what I'm going to call hypertempering, 00:01:34.320 --> 00:01:36.360 align:middle line:90% which is a Prince Rupert drop. 00:01:36.360 --> 00:01:38.920 align:middle line:84% So this is the furnace where we melt 00:01:38.920 --> 00:01:41.180 align:middle line:90% the glass that we have here. 00:01:41.180 --> 00:01:42.370 align:middle line:90% Mariel, are you over there? 00:01:42.370 --> 00:01:43.120 align:middle line:90% MARIEL BASS: Yeah. 00:01:43.120 --> 00:01:44.870 align:middle line:84% PETER HOUK: Could you grab a little cullet 00:01:44.870 --> 00:01:48.120 align:middle line:84% so we can show them what the raw material. 00:01:48.120 --> 00:01:50.440 align:middle line:84% So this is how the glass comes to us. 00:01:50.440 --> 00:01:51.860 align:middle line:90% We don't deal with quartz. 00:01:51.860 --> 00:01:54.460 align:middle line:84% We don't want airborne silica in this room. 00:01:54.460 --> 00:01:56.100 align:middle line:84% So we don't take the batch glass. 00:01:56.100 --> 00:01:59.970 align:middle line:84% We don't take the sand and the soda 00:01:59.970 --> 00:02:02.450 align:middle line:84% ash and the calcium carbonate, and we 00:02:02.450 --> 00:02:05.130 align:middle line:90% don't mix those things here. 00:02:05.130 --> 00:02:08.130 align:middle line:84% This furnace is designed so it has two chambers. 00:02:08.130 --> 00:02:11.330 align:middle line:84% On the right-hand side, we throw the glass in, 00:02:11.330 --> 00:02:14.490 align:middle line:84% and on the left-hand side, we have all the glass that we use. 00:02:14.490 --> 00:02:17.130 align:middle line:84% And the two chambers are divided by a wall. 00:02:17.130 --> 00:02:18.730 align:middle line:84% And there's a little hole in that wall 00:02:18.730 --> 00:02:21.810 align:middle line:84% so that there can be migration of glass from the charging 00:02:21.810 --> 00:02:25.210 align:middle line:84% side of the furnace to the gathering side of the furnace. 00:02:25.210 --> 00:02:27.370 align:middle line:84% So it's a continuous feed furnace, 00:02:27.370 --> 00:02:30.370 align:middle line:84% which is good because we use this lab every day. 00:02:30.370 --> 00:02:33.490 align:middle line:84% So we can't have a day where we fill the furnace 00:02:33.490 --> 00:02:35.680 align:middle line:84% and wait for all the bubbles to come out. 00:02:35.680 --> 00:02:37.930 align:middle line:84% We have to have a design of a furnace that can give us 00:02:37.930 --> 00:02:39.270 align:middle line:90% good glass every day. 00:02:39.270 --> 00:02:43.890 align:middle line:90% 00:02:43.890 --> 00:02:46.222 align:middle line:84% So we have two types of furnaces in here. 00:02:46.222 --> 00:02:47.930 align:middle line:84% There's the glass furnace there, where we 00:02:47.930 --> 00:02:49.990 align:middle line:90% melt a crucible full of glass. 00:02:49.990 --> 00:02:54.050 align:middle line:84% There's about probably 300, 350 pounds of molten 00:02:54.050 --> 00:02:56.210 align:middle line:90% glass in that furnace. 00:02:56.210 --> 00:02:58.190 align:middle line:84% And that furnace is on all the time. 00:02:58.190 --> 00:03:00.830 align:middle line:84% We don't turn it off until we have to rebuild it. 00:03:00.830 --> 00:03:04.390 align:middle line:84% So it may be on for five, six years at a time, all day, 00:03:04.390 --> 00:03:06.210 align:middle line:90% every day, all night. 00:03:06.210 --> 00:03:08.405 align:middle line:84% These furnaces are for reheating the glass, 00:03:08.405 --> 00:03:10.030 align:middle line:84% and they're about the same temperature, 00:03:10.030 --> 00:03:12.030 align:middle line:84% but we turn these off at the end of the day. 00:03:12.030 --> 00:03:25.208 align:middle line:90% 00:03:25.208 --> 00:03:27.250 align:middle line:84% MARIEL BASS: Glass plate is basically [INAUDIBLE] 00:03:27.250 --> 00:03:30.590 align:middle line:90% metal [INAUDIBLE] grinders. 00:03:30.590 --> 00:03:37.410 align:middle line:90% 00:03:37.410 --> 00:03:41.850 align:middle line:84% PETER HOUK: So I'm heating the two glasses together now. 00:03:41.850 --> 00:03:45.250 align:middle line:84% You saw how I put one just right on the side of the other. 00:03:45.250 --> 00:03:47.250 align:middle line:84% And I can't really mix them here. 00:03:47.250 --> 00:03:50.650 align:middle line:84% I'll never get them hot enough to make them homogeneous. 00:03:50.650 --> 00:03:52.870 align:middle line:84% I'm just trying to get everything hot again 00:03:52.870 --> 00:03:54.150 align:middle line:90% so we can pull it. 00:03:54.150 --> 00:04:16.940 align:middle line:90% 00:04:16.940 --> 00:04:19.519 align:middle line:84% Try to have more or less equal amounts of glass. 00:04:19.519 --> 00:04:50.400 align:middle line:90% 00:04:50.400 --> 00:04:50.900 align:middle line:90% OK. 00:04:50.900 --> 00:05:17.700 align:middle line:90% 00:05:17.700 --> 00:05:18.240 align:middle line:90% OK. 00:05:18.240 --> 00:05:21.500 align:middle line:90% 00:05:21.500 --> 00:05:22.760 align:middle line:90% Wow, that really went. 00:05:22.760 --> 00:05:27.820 align:middle line:90% 00:05:27.820 --> 00:05:30.280 align:middle line:84% I don't think I'm going to give up just yet on that. 00:05:30.280 --> 00:05:37.940 align:middle line:90% 00:05:37.940 --> 00:05:39.440 align:middle line:90% OK. 00:05:39.440 --> 00:05:59.152 align:middle line:90% 00:05:59.152 --> 00:06:04.370 align:middle line:90% There's definitely boro in that. 00:06:04.370 --> 00:06:04.870 align:middle line:90% Yeah. 00:06:04.870 --> 00:06:07.250 align:middle line:84% And you'll see that in The Prince Rupert drop, too. 00:06:07.250 --> 00:06:12.350 align:middle line:84% So this is another way of talking about stress in glass, 00:06:12.350 --> 00:06:15.110 align:middle line:84% is to talk about engineered stress in glass. 00:06:15.110 --> 00:06:17.570 align:middle line:84% So instead of putting two different glasses together, 00:06:17.570 --> 00:06:21.430 align:middle line:84% we're going to take a glass and suddenly chill the outside 00:06:21.430 --> 00:06:25.390 align:middle line:84% so the inside remains hot and the outside cools first 00:06:25.390 --> 00:06:27.850 align:middle line:90% and it compresses a little bit. 00:06:27.850 --> 00:06:30.890 align:middle line:84% And the outside-- or the inside would like to keep expanding, 00:06:30.890 --> 00:06:35.170 align:middle line:84% so you have tension and compression in conflict there. 00:06:35.170 --> 00:06:38.310 align:middle line:90% 00:06:38.310 --> 00:06:41.650 align:middle line:84% So that there are kind of two reasons to temper glass. 00:06:41.650 --> 00:06:46.010 align:middle line:84% One is it's stronger, it makes it stronger. 00:06:46.010 --> 00:06:49.630 align:middle line:90% But there's another one, too. 00:06:49.630 --> 00:06:51.550 align:middle line:90% When it breaks, what happens? 00:06:51.550 --> 00:06:56.150 align:middle line:84% Yeah, into small, little relatively harmless pieces. 00:06:56.150 --> 00:06:58.110 align:middle line:84% So if you're driving along on the highway 00:06:58.110 --> 00:07:00.543 align:middle line:84% and a rock flies into your windshield and your windshield 00:07:00.543 --> 00:07:02.710 align:middle line:84% breaks-- well, first of all, it's laminated usually, 00:07:02.710 --> 00:07:05.390 align:middle line:84% too, but it would break into little kind 00:07:05.390 --> 00:07:08.130 align:middle line:84% of Chichlet-sized glasses, piece of glass. 00:07:08.130 --> 00:07:13.390 align:middle line:84% So if a skyscraper-- bird flies into a skyscraper 60 stories up 00:07:13.390 --> 00:07:16.070 align:middle line:84% and breaks the window, you have little pellets 00:07:16.070 --> 00:07:19.630 align:middle line:84% of glass raining on you instead of giant shards of potentially 00:07:19.630 --> 00:07:21.190 align:middle line:90% lethal glass. 00:07:21.190 --> 00:07:25.310 align:middle line:84% So that's the other big reason for tempering glass. 00:07:25.310 --> 00:07:26.990 align:middle line:84% So what I'm going to show you now 00:07:26.990 --> 00:07:29.370 align:middle line:84% is an example of tempering glass, 00:07:29.370 --> 00:07:32.110 align:middle line:90% but in an even more extreme way. 00:07:32.110 --> 00:07:35.750 align:middle line:84% So in the factory setting, they'll use air. 00:07:35.750 --> 00:07:39.670 align:middle line:84% So they heat up the glass with natural-- or electricity, 00:07:39.670 --> 00:07:40.170 align:middle line:90% usually. 00:07:40.170 --> 00:07:44.630 align:middle line:84% So they'll be heating elements above and below the glass that 00:07:44.630 --> 00:07:46.990 align:middle line:84% heats the glass very quickly up to the transition 00:07:46.990 --> 00:07:48.430 align:middle line:90% temperature of the glass. 00:07:48.430 --> 00:07:52.950 align:middle line:84% And then it slides out of that zone on a flat bunch of rollers 00:07:52.950 --> 00:07:55.870 align:middle line:84% into another zone where it's being cooled with compressed air 00:07:55.870 --> 00:08:00.370 align:middle line:84% above and below quickly so it can induce stress in the glass. 00:08:00.370 --> 00:08:02.710 align:middle line:84% And the key is that it's done really evenly, 00:08:02.710 --> 00:08:05.470 align:middle line:84% so that there's no-- it's not colder over here 00:08:05.470 --> 00:08:07.730 align:middle line:84% than it is over here, or hotter over there. 00:08:07.730 --> 00:08:11.810 align:middle line:84% It's all very hot and then very cold. 00:08:11.810 --> 00:08:15.950 align:middle line:84% So because there's no unevenness in the heating or the chilling, 00:08:15.950 --> 00:08:18.470 align:middle line:84% the glass can go into even compression 00:08:18.470 --> 00:08:22.230 align:middle line:84% and stay very stressed out, but very strong. 00:08:22.230 --> 00:08:25.070 align:middle line:84% So we're going to use water to cool glass here. 00:08:25.070 --> 00:08:27.830 align:middle line:84% So you probably know water is a much more 00:08:27.830 --> 00:08:32.630 align:middle line:84% effective, dramatic, radical coolant than air. 00:08:32.630 --> 00:08:35.409 align:middle line:84% So it's going to generate a lot more stress in the glass. 00:08:35.409 --> 00:08:39.789 align:middle line:84% So we're going to take some furnace glass 00:08:39.789 --> 00:08:43.909 align:middle line:84% and ask it to cool down from 2150 degrees Fahrenheit 00:08:43.909 --> 00:08:47.010 align:middle line:84% to room temperature in a matter of seconds. 00:08:47.010 --> 00:08:51.680 align:middle line:90% 00:08:51.680 --> 00:08:52.980 align:middle line:90% Oh, hang on a second. 00:08:52.980 --> 00:08:57.000 align:middle line:90% 00:08:57.000 --> 00:08:58.180 align:middle line:90% Can I give that one to you? 00:08:58.180 --> 00:09:00.430 align:middle line:90% MARIEL BASS: Yes. 00:09:00.430 --> 00:09:02.180 align:middle line:84% PETER HOUK: I made one before you came in. 00:09:02.180 --> 00:09:03.360 align:middle line:90% Just in case. 00:09:03.360 --> 00:09:05.220 align:middle line:84% So these can be a little hard to make. 00:09:05.220 --> 00:09:08.540 align:middle line:90% They don't always cooperate. 00:09:08.540 --> 00:09:37.400 align:middle line:90% 00:09:37.400 --> 00:09:39.720 align:middle line:84% So that's just an aluminum tube filled 00:09:39.720 --> 00:09:42.080 align:middle line:90% with room-temperature water. 00:09:42.080 --> 00:09:44.880 align:middle line:84% And it's long enough that by the time 00:09:44.880 --> 00:09:48.200 align:middle line:84% the drop gets to the bottom, it's pretty solidified. 00:09:48.200 --> 00:09:51.320 align:middle line:90% So where's that one? 00:09:51.320 --> 00:09:52.880 align:middle line:90% This is perfect. 00:09:52.880 --> 00:09:53.500 align:middle line:90% All right. 00:09:53.500 --> 00:09:54.820 align:middle line:90% So you can break them. 00:09:54.820 --> 00:09:55.380 align:middle line:90% It's hard. 00:09:55.380 --> 00:09:57.840 align:middle line:84% You have to really put a lot of force into it. 00:09:57.840 --> 00:10:01.420 align:middle line:84% So usually, the way we break them is in this enclosed thing-- 00:10:01.420 --> 00:10:05.280 align:middle line:84% anyone else want to try to give it a try? 00:10:05.280 --> 00:10:06.760 align:middle line:90% No, you're good? 00:10:06.760 --> 00:10:07.840 align:middle line:90% OK. 00:10:07.840 --> 00:10:09.680 align:middle line:90% Trust and verify. 00:10:09.680 --> 00:10:10.180 align:middle line:90% All right. 00:10:10.180 --> 00:10:13.140 align:middle line:90% Well, so much stronger. 00:10:13.140 --> 00:10:17.560 align:middle line:90% 00:10:17.560 --> 00:10:24.080 align:middle line:84% Just so you know, this is regular glass unannealed. 00:10:24.080 --> 00:10:29.120 align:middle line:84% If we break this with the pliers, 00:10:29.120 --> 00:10:30.880 align:middle line:84% that's all it does because there's 00:10:30.880 --> 00:10:33.040 align:middle line:90% not too much stress in it. 00:10:33.040 --> 00:10:35.160 align:middle line:90% Come closer. 00:10:35.160 --> 00:10:38.500 align:middle line:84% On the other hand, this one, even where it's tiny like this, 00:10:38.500 --> 00:10:41.240 align:middle line:84% it was still in the water, so this part got tempered. 00:10:41.240 --> 00:10:43.320 align:middle line:84% Got tempered all the way up to there 00:10:43.320 --> 00:10:46.490 align:middle line:84% when it came out of the water and I looped it around. 00:10:46.490 --> 00:10:49.870 align:middle line:84% So keep your eye on the drop down there. 00:10:49.870 --> 00:10:51.890 align:middle line:84% Not what I'm doing, but on the drop, 00:10:51.890 --> 00:10:56.270 align:middle line:84% and I'll give you a countdown of 5, 4, 3, 2, 1-- 00:10:56.270 --> 00:10:59.270 align:middle line:90% 4, 3, 2, 1. 00:10:59.270 --> 00:11:05.610 align:middle line:90% 00:11:05.610 --> 00:11:10.770 align:middle line:84% So just breaking the surface of that compressed layer 00:11:10.770 --> 00:11:16.690 align:middle line:84% there makes the entire thing fail at the point of failure 00:11:16.690 --> 00:11:18.190 align:middle line:90% at-- how fast? 00:11:18.190 --> 00:11:22.850 align:middle line:90% 00:11:22.850 --> 00:11:24.050 align:middle line:90% AUDIENCE: At speed of sound. 00:11:24.050 --> 00:11:25.130 align:middle line:90% PETER HOUK: Fast. 00:11:25.130 --> 00:11:29.950 align:middle line:84% Speed of sound in glass, not in air, which is different, 00:11:29.950 --> 00:11:32.970 align:middle line:90% I think dramatically different. 00:11:32.970 --> 00:11:35.910 align:middle line:90% Something like 3x, 2x. 00:11:35.910 --> 00:11:38.090 align:middle line:90% AUDIENCE: [INAUDIBLE] 00:11:38.090 --> 00:11:40.650 align:middle line:90% PETER HOUK: Yeah. 00:11:40.650 --> 00:11:44.010 align:middle line:84% So then the size of the fracture here 00:11:44.010 --> 00:11:46.310 align:middle line:84% is an indication of how much stress. 00:11:46.310 --> 00:11:48.450 align:middle line:84% If you walk around the street and you 00:11:48.450 --> 00:11:50.490 align:middle line:84% see little pieces of leftover glass 00:11:50.490 --> 00:11:52.310 align:middle line:84% from where somebody's car window broke, 00:11:52.310 --> 00:11:55.410 align:middle line:84% they're about the size of my thumbnail, kind of roughly. 00:11:55.410 --> 00:11:57.710 align:middle line:84% But come closer and look at these. 00:11:57.710 --> 00:12:00.370 align:middle line:90% Yeah, much, much, much smaller. 00:12:00.370 --> 00:12:02.590 align:middle line:84% There's just so much stress in there. 00:12:02.590 --> 00:12:06.690 align:middle line:90% 00:12:06.690 --> 00:12:08.270 align:middle line:90% What is the shape of that? 00:12:08.270 --> 00:12:13.107 align:middle line:90% 00:12:13.107 --> 00:12:14.690 align:middle line:84% This is not the best example, but it's 00:12:14.690 --> 00:12:16.383 align:middle line:90% kind of cone shaped, right? 00:12:16.383 --> 00:12:17.050 align:middle line:90% AUDIENCE: Right. 00:12:17.050 --> 00:12:20.610 align:middle line:84% PETER HOUK: So I think what we're looking at here-- 00:12:20.610 --> 00:12:23.110 align:middle line:84% so I'm going to do a little chalk drawing on the floor. 00:12:23.110 --> 00:12:28.450 align:middle line:90% 00:12:28.450 --> 00:12:36.490 align:middle line:84% When the Prince Rupert drop fails, the center of the failure 00:12:36.490 --> 00:12:39.470 align:middle line:84% is right down the center, like that. 00:12:39.470 --> 00:12:42.250 align:middle line:90% 00:12:42.250 --> 00:12:46.360 align:middle line:84% And then you see this kind of thing. 00:12:46.360 --> 00:12:50.420 align:middle line:90% 00:12:50.420 --> 00:12:55.820 align:middle line:84% So it's falling down, but at this angle from the center 00:12:55.820 --> 00:12:57.640 align:middle line:90% of the axis of the failure. 00:12:57.640 --> 00:13:03.100 align:middle line:84% And this is a little artifact of the center and that angle 00:13:03.100 --> 00:13:05.680 align:middle line:84% at which the failure is occurring. 00:13:05.680 --> 00:13:08.780 align:middle line:90% 00:13:08.780 --> 00:13:11.460 align:middle line:90% Why that angle? 00:13:11.460 --> 00:13:15.117 align:middle line:84% AUDIENCE: Maybe it's the shear stress? 00:13:15.117 --> 00:13:16.200 align:middle line:90% PETER HOUK: I'll buy that. 00:13:16.200 --> 00:13:20.940 align:middle line:84% [LAUGHS] So that's all the way open. 00:13:20.940 --> 00:13:24.100 align:middle line:84% That's all the way cross-polarized. 00:13:24.100 --> 00:13:27.060 align:middle line:84% And you can see-- can you see the colors? 00:13:27.060 --> 00:13:30.300 align:middle line:84% There's a magenta and a green, and then all these little kind 00:13:30.300 --> 00:13:32.480 align:middle line:90% of striations in the glass. 00:13:32.480 --> 00:13:36.540 align:middle line:90% Those are all stress signs. 00:13:36.540 --> 00:13:40.300 align:middle line:84% Can you guys see any of the color in there? 00:13:40.300 --> 00:13:43.860 align:middle line:84% This is just a single chunk of white color 00:13:43.860 --> 00:13:46.100 align:middle line:90% pulled out and then twisted. 00:13:46.100 --> 00:13:51.580 align:middle line:84% So you get this kind of variable pitch sine wave here. 00:13:51.580 --> 00:13:55.660 align:middle line:84% And then this is more elaborate cane here, with a-- 00:13:55.660 --> 00:13:57.320 align:middle line:90% these are the MIT colors. 00:13:57.320 --> 00:14:01.240 align:middle line:84% So there's this red and a gray with a sine wave in the middle. 00:14:01.240 --> 00:14:06.420 align:middle line:84% And then these little filaments, little canes on the outside. 00:14:06.420 --> 00:14:10.360 align:middle line:84% So we would start with red cane and gray cane, 00:14:10.360 --> 00:14:14.380 align:middle line:84% combine them, and then pull it all hot while twisting. 00:14:14.380 --> 00:14:17.180 align:middle line:84% So just to show you a simple example of that, 00:14:17.180 --> 00:14:20.420 align:middle line:84% I'm going to pull some cane with this gold color. 00:14:20.420 --> 00:14:24.260 align:middle line:84% And then maybe we'll make something quick with cane, 00:14:24.260 --> 00:14:29.500 align:middle line:84% like a pumpkin or something-- something that can happen fast. 00:14:29.500 --> 00:14:33.180 align:middle line:90% So a couple ladders, please. 00:14:33.180 --> 00:14:41.830 align:middle line:84% So this is just fritted glass with colored oxides in it. 00:14:41.830 --> 00:14:43.910 align:middle line:84% So this is a transparent gold color that 00:14:43.910 --> 00:14:45.450 align:middle line:90% probably has a bit of silver-- 00:14:45.450 --> 00:14:48.310 align:middle line:90% 00:14:48.310 --> 00:14:52.150 align:middle line:84% silver salts, silver nitrate, probably. 00:14:52.150 --> 00:14:59.030 align:middle line:90% 00:14:59.030 --> 00:15:00.430 align:middle line:90% Does that sound right, JJ? 00:15:00.430 --> 00:15:01.130 align:middle line:90% What would-- 00:15:01.130 --> 00:15:03.457 align:middle line:90% AUDIENCE: [INAUDIBLE] 00:15:03.457 --> 00:15:05.290 align:middle line:84% PETER HOUK: We don't mix our own color here, 00:15:05.290 --> 00:15:12.990 align:middle line:84% but the colors have a lot of different oxides in them. 00:15:12.990 --> 00:15:17.250 align:middle line:84% The blues usually have some cobalt, sometimes copper. 00:15:17.250 --> 00:15:20.270 align:middle line:90% 00:15:20.270 --> 00:15:24.530 align:middle line:84% The reds can be nanoparticles of gold sometimes, 00:15:24.530 --> 00:15:27.130 align:middle line:84% or copper will give you a different red. 00:15:27.130 --> 00:15:29.830 align:middle line:90% 00:15:29.830 --> 00:15:32.750 align:middle line:90% Chromium makes green. 00:15:32.750 --> 00:15:36.030 align:middle line:90% So does copper. 00:15:36.030 --> 00:15:38.170 align:middle line:90% Iron will make green, too. 00:15:38.170 --> 00:16:06.070 align:middle line:90% 00:16:06.070 --> 00:16:10.130 align:middle line:84% I'll go once more and that's it for the color. 00:16:10.130 --> 00:16:47.950 align:middle line:90% 00:16:47.950 --> 00:16:50.030 align:middle line:84% So I'm just trying to melt the color in so it 00:16:50.030 --> 00:16:54.490 align:middle line:90% becomes a smooth surface. 00:16:54.490 --> 00:17:34.990 align:middle line:90% 00:17:34.990 --> 00:17:38.960 align:middle line:84% And then we'll get one final layer of glass on top, 00:17:38.960 --> 00:17:40.380 align:middle line:90% and then we'll pull the cane. 00:17:40.380 --> 00:18:18.080 align:middle line:90% 00:18:18.080 --> 00:18:21.780 align:middle line:84% Yeah, I'll take a post after you, after I gather. 00:18:21.780 --> 00:20:01.650 align:middle line:90% 00:20:01.650 --> 00:20:03.710 align:middle line:90% Hey, Mariel, we'll go this side. 00:20:03.710 --> 00:20:50.410 align:middle line:90% 00:20:50.410 --> 00:20:51.190 align:middle line:90% Ooh, I'm sorry. 00:20:51.190 --> 00:20:51.830 align:middle line:90% You all right? 00:20:51.830 --> 00:22:02.140 align:middle line:90% 00:22:02.140 --> 00:22:02.960 align:middle line:90% That's good. 00:22:02.960 --> 00:22:17.348 align:middle line:90% 00:22:17.348 --> 00:22:20.820 align:middle line:90% [HUMMING] 00:22:20.820 --> 00:22:29.260 align:middle line:90% 00:22:29.260 --> 00:22:30.120 align:middle line:90% No, thanks. 00:22:30.120 --> 00:22:42.660 align:middle line:90% 00:22:42.660 --> 00:22:44.160 align:middle line:90% So it's still kind of hot. 00:22:44.160 --> 00:22:45.780 align:middle line:84% You can grab it with the cold tweezers 00:22:45.780 --> 00:22:48.420 align:middle line:90% and stock it to break it. 00:22:48.420 --> 00:22:53.100 align:middle line:84% So you that cane that we made that had the borosilicate in it 00:22:53.100 --> 00:22:54.780 align:middle line:90% started to curve immediately. 00:22:54.780 --> 00:22:57.380 align:middle line:84% This remains really pretty straight. 00:22:57.380 --> 00:22:59.040 align:middle line:84% That one has a little bend in it, 00:22:59.040 --> 00:23:02.640 align:middle line:84% probably more because I didn't pull it all that much. 00:23:02.640 --> 00:23:06.700 align:middle line:84% There's very little stress in this glass. 00:23:06.700 --> 00:23:10.260 align:middle line:84% Anyway, this is kind of the way that we make starter cane. 00:23:10.260 --> 00:23:11.780 align:middle line:84% Any color that you want to use, you 00:23:11.780 --> 00:23:13.920 align:middle line:84% have to first make that color in cane. 00:23:13.920 --> 00:23:15.500 align:middle line:90% So this is gold. 00:23:15.500 --> 00:23:18.780 align:middle line:84% And then on the very outside of the glass, 00:23:18.780 --> 00:23:23.880 align:middle line:84% I picked up several sets-- two sets of eight or nine canes, 00:23:23.880 --> 00:23:28.100 align:middle line:84% and then we pull and we twist them. 00:23:28.100 --> 00:23:30.615 align:middle line:84% So yeah, you can heat up a plate. 00:23:30.615 --> 00:23:32.740 align:middle line:84% And I'll make something real quick out of this cane 00:23:32.740 --> 00:23:38.740 align:middle line:84% so you can see how we take canes and transform them 00:23:38.740 --> 00:23:42.600 align:middle line:84% from a bunch of separate objects into a single blown thing. 00:23:42.600 --> 00:23:47.380 align:middle line:90% 00:23:47.380 --> 00:23:47.880 align:middle line:90% Let's see. 00:23:47.880 --> 00:23:50.080 align:middle line:90% We got about 10 minutes. 00:23:50.080 --> 00:23:57.900 align:middle line:90% 00:23:57.900 --> 00:23:59.300 align:middle line:90% We'll use the MIT cane. 00:23:59.300 --> 00:24:02.500 align:middle line:84% In order to keep the canes from rolling of the plate-- 00:24:02.500 --> 00:24:05.500 align:middle line:84% so Mariel preheated this ceramic plate 00:24:05.500 --> 00:24:09.460 align:middle line:84% so that we can boost the heat of the canes 00:24:09.460 --> 00:24:11.900 align:middle line:84% up so that they don't thermally shock when we go 00:24:11.900 --> 00:24:13.840 align:middle line:90% to get them really, really hot. 00:24:13.840 --> 00:24:21.140 align:middle line:90% 00:24:21.140 --> 00:24:25.720 align:middle line:84% So while the plate is still hot, I'll set up the cane. 00:24:25.720 --> 00:24:38.470 align:middle line:90% 00:24:38.470 --> 00:24:42.470 align:middle line:84% We have alternating red and gray and red and gray In? 00:24:42.470 --> 00:24:44.650 align:middle line:90% This particular design. 00:24:44.650 --> 00:24:49.050 align:middle line:84% There's no real reason other than aesthetic. 00:24:49.050 --> 00:25:04.070 align:middle line:90% 00:25:04.070 --> 00:25:08.350 align:middle line:84% And then I want you to look at these calipers. 00:25:08.350 --> 00:25:14.214 align:middle line:84% So these calipers are two-sided calipers 00:25:14.214 --> 00:25:22.990 align:middle line:84% that I can use to measure this length of cane 00:25:22.990 --> 00:25:27.890 align:middle line:84% and then divide it by pi and end up with that diameter. 00:25:27.890 --> 00:25:35.302 align:middle line:90% 00:25:35.302 --> 00:25:36.510 align:middle line:90% MARIEL BASS: Tray right here. 00:25:36.510 --> 00:25:38.830 align:middle line:84% PETER HOUK: Oh yeah, let's try it. 00:25:38.830 --> 00:25:39.850 align:middle line:90% MARIEL BASS: [INAUDIBLE] 00:25:39.850 --> 00:25:40.517 align:middle line:90% PETER HOUK: Hmm? 00:25:40.517 --> 00:25:44.230 align:middle line:84% MARIEL BASS: It's got glass on it. 00:25:44.230 --> 00:25:45.910 align:middle line:90% PETER HOUK: Oh, I see. 00:25:45.910 --> 00:25:46.610 align:middle line:90% That's good. 00:25:46.610 --> 00:25:49.453 align:middle line:90% 00:25:49.453 --> 00:25:51.870 align:middle line:84% So what I'm going to do is we'll get it hot enough that we 00:25:51.870 --> 00:25:53.330 align:middle line:90% can fuse the canes together. 00:25:53.330 --> 00:25:56.950 align:middle line:84% I will roll them up into a cylinder, close it off, 00:25:56.950 --> 00:25:59.330 align:middle line:84% and it becomes inflatable at that point, 00:25:59.330 --> 00:26:01.250 align:middle line:90% so it can be made into a bubble. 00:26:01.250 --> 00:26:15.790 align:middle line:90% 00:26:15.790 --> 00:26:19.290 align:middle line:84% So to prepare to make this object-- this is a blowpipe. 00:26:19.290 --> 00:26:20.050 align:middle line:90% So it's hollow. 00:26:20.050 --> 00:26:22.510 align:middle line:84% I can blow through it and introduce air 00:26:22.510 --> 00:26:24.970 align:middle line:84% into any glass I have on this side. 00:26:24.970 --> 00:26:31.057 align:middle line:90% 00:26:31.057 --> 00:26:32.640 align:middle line:84% So I have to make something that looks 00:26:32.640 --> 00:26:35.280 align:middle line:84% kind of like a donut of glass on the end of this, 00:26:35.280 --> 00:26:38.920 align:middle line:84% but it has to still be open so that I can breathe air into it. 00:26:38.920 --> 00:26:42.780 align:middle line:84% So I can't just pick up glass and have a closed bubble. 00:26:42.780 --> 00:26:45.280 align:middle line:90% It has to be an open bubble. 00:26:45.280 --> 00:26:49.680 align:middle line:84% So the way I do that is I'll get a little tiny gather of glass 00:26:49.680 --> 00:26:52.260 align:middle line:90% on the end of the blowpipe. 00:26:52.260 --> 00:26:57.480 align:middle line:90% 00:26:57.480 --> 00:27:01.360 align:middle line:90% Just a very even, small gather. 00:27:01.360 --> 00:27:07.140 align:middle line:84% And I hold it up and let the glass fall back onto the pipe. 00:27:07.140 --> 00:27:09.500 align:middle line:84% And then I'm going to put some air in it. 00:27:09.500 --> 00:27:12.520 align:middle line:90% 00:27:12.520 --> 00:27:18.780 align:middle line:84% Blow a bubble and then pop the bubble back in the furnace. 00:27:18.780 --> 00:27:22.000 align:middle line:90% 00:27:22.000 --> 00:27:24.260 align:middle line:90% And now I have an open bubble. 00:27:24.260 --> 00:27:34.080 align:middle line:90% 00:27:34.080 --> 00:27:38.160 align:middle line:84% And I'm just pulling the glass away from the hole, 00:27:38.160 --> 00:27:41.920 align:middle line:84% using my calipers now to get in the neighborhood 00:27:41.920 --> 00:27:43.340 align:middle line:90% of the right diameter. 00:27:43.340 --> 00:27:54.320 align:middle line:90% 00:27:54.320 --> 00:27:56.440 align:middle line:84% A lot of turning and glass blowing, 00:27:56.440 --> 00:27:59.860 align:middle line:84% I'm using the centrifugal force to spin the shape. 00:27:59.860 --> 00:28:02.760 align:middle line:90% 00:28:02.760 --> 00:28:06.360 align:middle line:84% You really learn how to work with gravity 00:28:06.360 --> 00:28:07.640 align:middle line:90% when you blow glass. 00:28:07.640 --> 00:28:09.180 align:middle line:90% Gravity can be your friend. 00:28:09.180 --> 00:28:12.200 align:middle line:90% It can also be your enemy. 00:28:12.200 --> 00:28:14.280 align:middle line:84% But under the right conditions, you 00:28:14.280 --> 00:28:18.000 align:middle line:84% can get a lot of work done by using centrifugal force 00:28:18.000 --> 00:28:20.860 align:middle line:90% and hanging things down. 00:28:20.860 --> 00:28:24.450 align:middle line:90% 00:28:24.450 --> 00:28:25.510 align:middle line:90% That's probably ready. 00:28:25.510 --> 00:28:26.290 align:middle line:90% Ooh, you OK? 00:28:26.290 --> 00:28:27.040 align:middle line:90% MARIEL BASS: Yeah. 00:28:27.040 --> 00:28:47.770 align:middle line:90% 00:28:47.770 --> 00:28:52.330 align:middle line:84% PETER HOUK: So timing becomes very important here. 00:28:52.330 --> 00:28:55.970 align:middle line:84% Mariel needs to heat up the cane enough 00:28:55.970 --> 00:28:58.330 align:middle line:84% that it doesn't shock when I pick it up, but not 00:28:58.330 --> 00:28:59.890 align:middle line:84% so much that it sticks to the plate 00:28:59.890 --> 00:29:03.090 align:middle line:84% and doesn't want to come of the plate. 00:29:03.090 --> 00:29:04.550 align:middle line:90% Meanwhile, I'm kind of watching. 00:29:04.550 --> 00:29:07.430 align:middle line:84% I don't want to be too cold here, or too hot. 00:29:07.430 --> 00:29:15.610 align:middle line:90% 00:29:15.610 --> 00:29:19.690 align:middle line:84% So I'm watching now and thinking about my timing 00:29:19.690 --> 00:29:22.810 align:middle line:84% while I watch how hot the cane is. 00:29:22.810 --> 00:29:26.290 align:middle line:84% It looks like it's picking up heat, starting to glow. 00:29:26.290 --> 00:29:28.670 align:middle line:84% Mariel will probably squish it a little bit here. 00:29:28.670 --> 00:29:31.490 align:middle line:90% 00:29:31.490 --> 00:29:34.630 align:middle line:90% Probably at least one more heat. 00:29:34.630 --> 00:29:46.610 align:middle line:90% 00:29:46.610 --> 00:29:47.950 align:middle line:90% Yeah, you can get it hotter. 00:29:47.950 --> 00:29:49.470 align:middle line:84% There's a bunch of boro in there. 00:29:49.470 --> 00:29:52.130 align:middle line:90% 00:29:52.130 --> 00:29:54.470 align:middle line:90% Just say another 10 or 15. 00:29:54.470 --> 00:30:07.030 align:middle line:90% 00:30:07.030 --> 00:30:07.530 align:middle line:90% OK. 00:30:07.530 --> 00:30:23.660 align:middle line:90% 00:30:23.660 --> 00:30:24.360 align:middle line:90% Can I get it? 00:30:24.360 --> 00:30:25.402 align:middle line:90% MARIEL BASS: Yeah, ready. 00:30:25.402 --> 00:30:33.540 align:middle line:90% 00:30:33.540 --> 00:30:35.803 align:middle line:90% Bring them over there. 00:30:35.803 --> 00:30:36.720 align:middle line:90% PETER HOUK: Thank you. 00:30:36.720 --> 00:30:42.540 align:middle line:90% 00:30:42.540 --> 00:30:45.540 align:middle line:84% This is just to get off any dust that might have been on the kiln 00:30:45.540 --> 00:30:49.020 align:middle line:90% shelf, because now's the time. 00:30:49.020 --> 00:30:53.660 align:middle line:84% Once I start heating it up towards 2000 degrees, 00:30:53.660 --> 00:30:56.160 align:middle line:84% anything that's on there will stick to the surface. 00:30:56.160 --> 00:31:10.260 align:middle line:90% 00:31:10.260 --> 00:31:12.660 align:middle line:84% So now just a little adjustment to make sure 00:31:12.660 --> 00:31:17.220 align:middle line:84% that the canes are all stuck together 00:31:17.220 --> 00:31:19.200 align:middle line:90% where I came around and joined. 00:31:19.200 --> 00:31:21.500 align:middle line:90% I can't even find it anymore. 00:31:21.500 --> 00:31:22.520 align:middle line:90% I think it's there. 00:31:22.520 --> 00:31:31.620 align:middle line:90% 00:31:31.620 --> 00:31:34.700 align:middle line:84% Yeah, I think you could go up to 4 on that garage. 00:31:34.700 --> 00:31:37.940 align:middle line:84% It's not going to overheat anytime soon. 00:31:37.940 --> 00:31:43.910 align:middle line:90% 00:31:43.910 --> 00:31:47.580 align:middle line:84% So now those canes are joined along their length 00:31:47.580 --> 00:31:51.580 align:middle line:84% in a very kind of provisional way. 00:31:51.580 --> 00:31:54.100 align:middle line:84% I can't blow into this yet because it's still 00:31:54.100 --> 00:31:56.500 align:middle line:90% open on the bottom. 00:31:56.500 --> 00:32:01.740 align:middle line:84% So what I'm going to do is roll all the canes on the steel table 00:32:01.740 --> 00:32:08.060 align:middle line:84% here, the marver, to try to increase their surface 00:32:08.060 --> 00:32:18.460 align:middle line:84% area at the point of contact so that when 00:32:18.460 --> 00:32:21.220 align:middle line:84% I go to blow this thing, it doesn't want to open up 00:32:21.220 --> 00:32:23.540 align:middle line:90% at the joint between the canes. 00:32:23.540 --> 00:32:26.580 align:middle line:84% That's one of the first things that beginners learn here, 00:32:26.580 --> 00:32:29.280 align:middle line:84% is that if they don't join their canes together enough, 00:32:29.280 --> 00:32:34.020 align:middle line:84% you get a hole, and then that's a game over situation. 00:32:34.020 --> 00:32:36.780 align:middle line:84% So I'll take a couple of heats and just 00:32:36.780 --> 00:32:40.040 align:middle line:84% make sure I'm really joining them together 00:32:40.040 --> 00:32:43.160 align:middle line:90% well by rolling and smashing. 00:32:43.160 --> 00:32:56.620 align:middle line:90% 00:32:56.620 --> 00:32:58.080 align:middle line:90% OK, you got the torch? 00:32:58.080 --> 00:33:02.260 align:middle line:90% 00:33:02.260 --> 00:33:06.200 align:middle line:84% We'll do one more roll and smash and then I'll close it up. 00:33:06.200 --> 00:33:09.580 align:middle line:90% 00:33:09.580 --> 00:33:10.080 align:middle line:90% All right. 00:33:10.080 --> 00:33:15.400 align:middle line:84% The next thing I'm going to do is close this off at the end 00:33:15.400 --> 00:33:17.910 align:middle line:90% so that it can be blown. 00:33:17.910 --> 00:33:47.510 align:middle line:90% 00:33:47.510 --> 00:33:48.510 align:middle line:90% No. 00:33:48.510 --> 00:33:49.850 align:middle line:90% It's OK. 00:33:49.850 --> 00:33:50.350 align:middle line:90% Thanks. 00:33:50.350 --> 00:34:05.270 align:middle line:90% 00:34:05.270 --> 00:34:06.490 align:middle line:90% Now it's closed. 00:34:06.490 --> 00:34:10.385 align:middle line:90% 00:34:10.385 --> 00:34:13.150 align:middle line:84% Probably just use a-- put a clear stem on it, probably. 00:34:13.150 --> 00:35:06.830 align:middle line:90% 00:35:06.830 --> 00:35:10.750 align:middle line:84% So I did that because I could tell 00:35:10.750 --> 00:35:16.440 align:middle line:84% it was a little colder near the end where the metal of the pipe 00:35:16.440 --> 00:35:17.960 align:middle line:84% is, because the metal of the pipe 00:35:17.960 --> 00:35:21.840 align:middle line:84% has been acting as a heat sink and taking 00:35:21.840 --> 00:35:24.160 align:middle line:90% heat out of that region. 00:35:24.160 --> 00:35:26.540 align:middle line:84% So that was a way of evening out the heat, 00:35:26.540 --> 00:35:28.720 align:middle line:84% using the torch to point it at that one area 00:35:28.720 --> 00:35:30.500 align:middle line:84% where I thought it was a little colder. 00:35:30.500 --> 00:35:42.880 align:middle line:90% 00:35:42.880 --> 00:35:45.840 align:middle line:84% And this is-- I'm now using just a foot 00:35:45.840 --> 00:35:55.520 align:middle line:84% pedal and compressed air to introduce air into this bubble. 00:35:55.520 --> 00:35:58.440 align:middle line:84% We developed this system during COVID 00:35:58.440 --> 00:36:00.280 align:middle line:84% so that people could blow glass in here 00:36:00.280 --> 00:36:02.420 align:middle line:84% without touching the pipe with their mouth. 00:36:02.420 --> 00:36:51.680 align:middle line:90% 00:36:51.680 --> 00:36:52.880 align:middle line:90% MARIEL BASS: First? 00:36:52.880 --> 00:36:54.700 align:middle line:84% PETER HOUK: No, let's do the stem first. 00:36:54.700 --> 00:36:56.400 align:middle line:90% MARIEL BASS: OK, [INAUDIBLE]. 00:36:56.400 --> 00:36:59.200 align:middle line:84% PETER HOUK: Yeah, yeah, you can start it up right now. 00:36:59.200 --> 00:37:00.800 align:middle line:90% Just a clear one. 00:37:00.800 --> 00:37:01.800 align:middle line:90% MARIEL BASS: Sit there? 00:37:01.800 --> 00:37:02.467 align:middle line:90% PETER HOUK: Yep. 00:37:02.467 --> 00:37:12.392 align:middle line:90% 00:37:12.392 --> 00:37:13.850 align:middle line:84% So I'll bring this over and you can 00:37:13.850 --> 00:37:18.170 align:middle line:84% see how the cane changed as it got mapped 00:37:18.170 --> 00:37:21.490 align:middle line:90% onto this much wider surface. 00:37:21.490 --> 00:37:22.250 align:middle line:90% AUDIENCE: Wow. 00:37:22.250 --> 00:37:25.022 align:middle line:84% PETER HOUK: So it's closer to flat than round now. 00:37:25.022 --> 00:37:25.730 align:middle line:90% AUDIENCE: Mm-hmm. 00:37:25.730 --> 00:37:28.312 align:middle line:90% 00:37:28.312 --> 00:37:29.770 align:middle line:84% PETER HOUK: So that's something you 00:37:29.770 --> 00:37:31.470 align:middle line:84% have to think about when you make cane. 00:37:31.470 --> 00:37:33.830 align:middle line:84% What's it going to look like in the end? 00:37:33.830 --> 00:38:36.370 align:middle line:90% 00:38:36.370 --> 00:38:39.930 align:middle line:84% So Mariel is getting the stem ready now. 00:38:39.930 --> 00:38:42.090 align:middle line:84% And again, I'm paying attention to what 00:38:42.090 --> 00:38:45.890 align:middle line:84% she's doing it so that I can control the timing. 00:38:45.890 --> 00:38:47.890 align:middle line:84% I don't want that to be added to this 00:38:47.890 --> 00:38:50.590 align:middle line:90% when it's too hot or too cold. 00:38:50.590 --> 00:39:00.050 align:middle line:90% 00:39:00.050 --> 00:39:02.670 align:middle line:84% OK, I'll take a quick flash when you go in. 00:39:02.670 --> 00:39:06.290 align:middle line:90% AUDIENCE: [INAUDIBLE] 00:39:06.290 --> 00:39:08.820 align:middle line:84% PETER HOUK: Yeah, spinning it because it's still hot enough 00:39:08.820 --> 00:39:12.680 align:middle line:84% that the glass could fall off center if I don't keep turning. 00:39:12.680 --> 00:39:37.240 align:middle line:90% 00:39:37.240 --> 00:39:37.740 align:middle line:90% Clip. 00:39:37.740 --> 00:40:01.820 align:middle line:90% 00:40:01.820 --> 00:40:02.360 align:middle line:90% Nice. 00:40:02.360 --> 00:41:08.540 align:middle line:90% 00:41:08.540 --> 00:41:09.360 align:middle line:90% All right, Mariel. 00:41:09.360 --> 00:41:18.766 align:middle line:84% So I'll torch this, and then you can give that a quick flash 00:41:18.766 --> 00:41:20.360 align:middle line:90% and come on over with it. 00:41:20.360 --> 00:41:28.780 align:middle line:90% 00:41:28.780 --> 00:41:31.120 align:middle line:84% Let me just locate where I want to put it. 00:41:31.120 --> 00:41:38.640 align:middle line:90% 00:41:38.640 --> 00:41:39.140 align:middle line:90% OK. 00:41:39.140 --> 00:42:36.720 align:middle line:90% 00:42:36.720 --> 00:42:37.930 align:middle line:90% So it's done. 00:42:37.930 --> 00:42:39.050 align:middle line:90% We'll put it away now. 00:42:39.050 --> 00:42:57.510 align:middle line:90% 00:42:57.510 --> 00:43:01.390 align:middle line:84% So to avoid thermal shock, we can't just let this cool 00:43:01.390 --> 00:43:03.550 align:middle line:90% as fast as it would like to. 00:43:03.550 --> 00:43:08.450 align:middle line:84% We have to cool it down slowly in one of our ovens over there. 00:43:08.450 --> 00:43:12.230 align:middle line:84% So we'll load it in the oven, and then tomorrow, it 00:43:12.230 --> 00:43:17.550 align:middle line:84% will come out after having ramped down overnight 00:43:17.550 --> 00:43:19.250 align:middle line:90% over about eight hours. 00:43:19.250 --> 00:43:22.310 align:middle line:90% 00:43:22.310 --> 00:43:25.430 align:middle line:84% So right now, I'll just put a little drop of water 00:43:25.430 --> 00:43:30.310 align:middle line:84% where I made the neckline with the tool here. 00:43:30.310 --> 00:43:33.310 align:middle line:84% And that water will shock the glass 00:43:33.310 --> 00:43:34.790 align:middle line:84% just a little bit in that place so 00:43:34.790 --> 00:43:36.930 align:middle line:84% that it wants to come off right there. 00:43:36.930 --> 00:43:43.190 align:middle line:90% 00:43:43.190 --> 00:43:45.650 align:middle line:84% And then we're just going to melt in the break off 00:43:45.650 --> 00:43:46.690 align:middle line:90% so it's not sharp. 00:43:46.690 --> 00:43:48.190 align:middle line:90% Do I need to spoon that or-- 00:43:48.190 --> 00:43:50.590 align:middle line:90% it doesn't really look like it. 00:43:50.590 --> 00:43:52.090 align:middle line:90% OK. 00:43:52.090 --> 00:43:55.590 align:middle line:90% 00:43:55.590 --> 00:43:57.370 align:middle line:90% And then we put it in the oven. 00:43:57.370 --> 00:44:04.020 align:middle line:90% 00:44:04.020 --> 00:44:06.520 align:middle line:84% Seems a little counterintuitive that you would put something 00:44:06.520 --> 00:44:09.480 align:middle line:84% in an oven to cool it down, but that's what we do. 00:44:09.480 --> 00:44:13.480 align:middle line:84% So you can see that the temperature of that bottom oven 00:44:13.480 --> 00:44:17.840 align:middle line:90% is at 884 right now, Fahrenheit. 00:44:17.840 --> 00:44:21.640 align:middle line:84% This is at 2100, and that glory hole over there 00:44:21.640 --> 00:44:23.100 align:middle line:90% is the same temperature. 00:44:23.100 --> 00:44:27.130 align:middle line:84% So for us, things get cold when they get below 1000 degrees 00:44:27.130 --> 00:44:29.280 align:middle line:84% Fahrenheit because that's below the transition 00:44:29.280 --> 00:44:30.920 align:middle line:90% temperature of the glass. 00:44:30.920 --> 00:44:34.760 align:middle line:84% So that's a good temperature to put the glass in there, 00:44:34.760 --> 00:44:37.480 align:middle line:84% because it won't continue to deform at all. 00:44:37.480 --> 00:44:41.080 align:middle line:84% It will stay there happily at 1000 degrees, or just below, 00:44:41.080 --> 00:44:44.480 align:middle line:90% about 930 degrees, all day long. 00:44:44.480 --> 00:44:46.740 align:middle line:84% And then we'll cool it down slowly overnight, 00:44:46.740 --> 00:44:49.920 align:middle line:84% and then there won't be any stresses left in the glass 00:44:49.920 --> 00:44:51.640 align:middle line:90% if we do it all right. 00:44:51.640 --> 00:44:54.020 align:middle line:90% It's a little bit more complex. 00:44:54.020 --> 00:44:56.920 align:middle line:84% So maybe where's my piece of chalk? 00:44:56.920 --> 00:44:59.820 align:middle line:84% I can draw what the ramp looks like. 00:44:59.820 --> 00:45:11.640 align:middle line:90% 00:45:11.640 --> 00:45:16.200 align:middle line:84% So if this is temperature, and this is time, 00:45:16.200 --> 00:45:18.840 align:middle line:84% we're going to start at 930, which 00:45:18.840 --> 00:45:21.240 align:middle line:90% is our annealing temperature. 00:45:21.240 --> 00:45:25.440 align:middle line:84% And we hold there as long as we need to, all day long. 00:45:25.440 --> 00:45:29.460 align:middle line:84% And then you have to stay at that temperature 00:45:29.460 --> 00:45:33.440 align:middle line:84% so that the temperature can even out within the piece that you're 00:45:33.440 --> 00:45:33.940 align:middle line:90% using. 00:45:33.940 --> 00:45:37.000 align:middle line:84% So if you put in something that's really thin, 00:45:37.000 --> 00:45:39.880 align:middle line:84% you can hold it at 930 for only like a half an hour 00:45:39.880 --> 00:45:41.400 align:middle line:90% and it will be OK. 00:45:41.400 --> 00:45:45.200 align:middle line:84% But if you're making the Hubble telescope lens, 00:45:45.200 --> 00:45:50.680 align:middle line:84% then you need to anneal that for a year because it's that thick. 00:45:50.680 --> 00:45:53.680 align:middle line:84% So there's a geometric relationship between thickness 00:45:53.680 --> 00:45:55.680 align:middle line:90% and annealing. 00:45:55.680 --> 00:45:59.930 align:middle line:84% So after you've annealed for enough time, 00:45:59.930 --> 00:46:12.330 align:middle line:84% then you can go down a little more gradually to 750 00:46:12.330 --> 00:46:14.770 align:middle line:84% over-- this might be an hour, and this 00:46:14.770 --> 00:46:21.490 align:middle line:84% might be two hours, to get past the strain point of the glass. 00:46:21.490 --> 00:46:25.190 align:middle line:84% And then you can go down really pretty quickly. 00:46:25.190 --> 00:46:33.690 align:middle line:84% This might be another four hours to, say, 300. 00:46:33.690 --> 00:46:37.530 align:middle line:84% So this is where you have to be kind of gentle 00:46:37.530 --> 00:46:39.450 align:middle line:90% going through the strain-- 00:46:39.450 --> 00:46:40.970 align:middle line:84% the strain part of the glass, which 00:46:40.970 --> 00:46:45.710 align:middle line:84% is about 100 to 150 degrees below the annealing temperature, 00:46:45.710 --> 00:46:47.690 align:middle line:90% generally, of our glass. 00:46:47.690 --> 00:46:51.330 align:middle line:84% So that's what the profile looks like. 00:46:51.330 --> 00:46:53.960 align:middle line:90% It's about eight hours. 00:46:53.960 --> 00:46:59.000 align:middle line:90%