The Manhattan Project

Raymond Grills's Interview

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Dr. Raymond Grills was a DuPont physical chemist who worked at the University of Chicago Met Lab and later at Hanford during the Manhattan Project. While at Hanford, he was one of two men who invented the canning process that sealed uranium slugs for use in Hanford’s water-cooled nuclear reactors. In this interview, he describes the challenges and pressures he and his colleagues had to overcome, and explains why the canning had to be designed perfectly. He also describes humorous encounters with a machinist and a railroad porter while transporting uranium slugs.
Manhattan Project Location(s): 
Date of Interview: 
January 25, 1965
Location of the Interview: 
Wilmington
Collections: 
Transcript: 

Stephane Groueff: Dr. Raymond Grills, DuPont, Wilmington.

Raymond Grills: I’m not sure just where we ought to start on explaining this, but perhaps we’ll explain it in this way. First off, the slug itself was a piece of metal, an inch to an inch-and-a-half in diameter and approximately five to six inches long. This material, which was of course uranium, was going to have to be put into the pile itself. The pile was going to be cooled by circulating water through it. The uranium had to be protected from this cooling water, and it had to be protected in general because if it got a leak in the slug, then the whole pile would become active and would shut down and you could have quite a disastrous effect.

We knew what the requirements were, and mainly that the uranium had to be encased in a material to protect it. I’m staying away now from any real technical situations here. It had to be encased like a casing on a ­­frankfurter, so to speak. This had to work perfect. You could not afford to have a failure, because you only had some thousand of these inside of the pile. Only one of them could cause you to have a failure.

So, we had to get a process that was essentially foolproof. As a matter of fact, we later decided the only way to do this was have 100% test inspection of these. We had two or three different processes to work this out. And we ended up putting an aluminum casing around the uranium. But, we had to have a perfectly good bond between the uranium and aluminum. It had to be an excellent seal, essentially perfect.

To arrive around to this, we had three or four different processes to look at. We would work with these processes, and we devised a test method whereby we put them in a big steam autoclave and subjected them to high temperatures and pressures. They would fail. We got the process where maybe we could get 90% yield or 95%, but essentially this was not acceptable at all. You just had to have it perfect. There just couldn’t be any of them failing. We knew that we had to keep working until we came up with a method that when we put it through our most stringent test, it never failed.

We worked on this. Time got short. We were working with two or three different laboratories at our own company and universities: the University of Illinois, University of Chicago. We were working with people from Brown University. We were working with people from Iowa State. We had the benefit of the consultation of all the metallurgists. We went out to talk to the aluminum company. We had the benefit of real top-notch talent to tell us about this. And we kept working and time got shorter, because we left the University of Chicago. We went out to Hanford to set up there.

Everything else was progressing. They were getting the pile area ready and the separation area ready, and here we were at the very front of the process. Until this got done, nothing could get done. We got a lot of top-level attention. Mr. [Crawford] Greenewalt used to drop over – because at that time, as you know, he was the technical director and advisor – and look at this. We had a lot of attention on a lot of people.

Now, finally it got to the place where none of the real complicated things we were trying were bringing us results. One evening, another man by the name of Ed Smith and myself finally decided that what the problem was that the heat transfer was not right in any of the processes that we had. The way to get perfect heat transfer was to do this operation, what we call canning the slug, underneath the level of the bath that we were using to do the coating with.

So, we decided to do it by hand, so to speak: with tongs, obviously. But we did this under the surface of the bath. And by doing it under the surface of the bath, we got perfectly good, uniform heat transfer. We were able to encase the uranium slug into the aluminum tube. This was at a very high temperature. You had to do it in a hurry or else your aluminum would melt.

The first time we did it, we burnt a hole through the first tube. But we tried it again, and we were able to do it. Essentially, that evening, we were able to can up slugs that looked to us like they were pretty good. Because they were the best we’d seen, just from the way the coating had gone on the uranium, and the way we were able to slap it in place and so forth.

We took those the next day and put them through our test, and they were all acceptable. We didn’t say very much about it. We got out the next night, and we put up a whole group of them. Put them in the test bath and in the autoclave. They worked.

Now, in a very short time, within essentially a few days, we had abandoned all the high-powered mechanical handling techniques and heating devices and dipping arrangements. We just got ourselves open baths of our coating material, and were getting the men to do this underneath the surface and—

Groueff: Manually.

Grills: Manually. This is how we made the first batch that went in the first pile. As a result of this, we were able to put them into these large autoclaves. We had to make quite a few thousand of them, you see. We were able to test and before long, where we had these records of quite a few failures, we were knocking them off essentially perfect. And this in general is the story of what happened.

Now, as you look back on it, it seems quite simple. You say, “Gosh, a lot of people could have thought of doing this.” This is true as you look back on most things, but the truth of the matter is that we did this essentially manually. Now, I don’t know what they’re doing today, but as recent as a few years ago, they were still doing this essentially this way because it’s such a simple thing to do. There wasn’t any use to spend a lot more effort in trying. The amount you’re going to do, you’re going to get it over with, and once you got one pile built, you don’t need another one or so.

Groueff: All those thousands were produced manually?

Grills: For the first one. Now, let me say to you that I left the Manhattan Project in April of ’46 and the war was over in August of ’46 [misspoke – 1945] as I remember it. My knowledge of this stops at this point.

But yes sir. On the first one, we did it all. We had devised some very ingenious effective mechanical devices for our dipping and so forth and for heating. The problem was to get uniform heating around this uranium and get a uniform heated can. Put the two together; make a weld on the end of the can with a special spot-welding arrangement. If you want to weld thin aluminum—and this aluminum was only a few thousandths thick – this takes a fancy welding arrangement. We obsoleted all this stuff through this technique, because we could cap it underneath the surface and—

Groueff: Where was that? In what laboratory?

Grills: This was done in the 300 Area at Hanford.

Groueff: At Hanford. So, that night—do you remember the date, more or less?

Grills: No, I don’t. This would have been sometime either late ’45 or early ’46. I’m not—that’s right, ’44 and ’45, yes.

Groueff: Really, the last few months before the bomb?

Grills: Oh, yes. This was getting very close. The heat was on us because everything else seemed to be falling into shape. Now, let me say as an individual working on this project, I had an idea of what we were trying to accomplish, but I didn’t know any of the difficulties that the men were going to be in the pile area or in the separation area or in any of the rest of the areas. Now, they may have had problems just as complicated and so forth, but all we could hear was, “You boys up there in that 300 Area, the raw material preparation area, this is not coming along. What are we going to do? We can’t start otherwise.” And so forth.

There was a great deal of genuine, sincere urgency to get this thing done. I happened to have the two groups of people that were working on this, and naturally you felt the pressure of this. I mean, you as an individual didn’t want to be the guy stopping the thing from going on. I will hasten to say that I had no idea what the other problems people were up against.

Groueff: Yeah.

Grills: They were maybe just as involved. All I knew was that we had a job to do.

Groueff: What was your job at that time at Hanford?

Grills: I don’t know what the title was. You’d have to look it up. I don’t even remember. I was something like supervisor of the metallurgical development group. I think this is subject to records. You could look it up and see what my exact title was.

Groueff: But you were—

Grills: The way I came about on this job – first, in the [DuPont] Company, I started as a research chemist and worked the experimental station in nylon research. Then I worked in the military explosives part of the business. I had worked as a chemical engineer and so forth. When I was transferred out to Hanford, I first was asked to report to the University of Chicago.

At that time, people weren’t real clear where they were going to work. They were trying to use your talents most anyway they could. It just so happens that when I arrived, they were needing people to work in the metallurgical part of the business. I’m sure that if I had come a week later or a week before, I might have ended up somewhere else, because they were not too precise. I happen to be a physical chemist by training, and this was fairly close to metallurgy.

Groueff: So you were not a metallurgist, a specialist?

Grills: No, no. I’m not a metallurgist. When I reported at the University of Chicago, I reported to a man by the name of Howe, John Howe, who was a professor of metallurgy at Brown University. John assigned me to what we call the canning process. After I was at the University for a while, I discovered that we had a group that were working up at our laboratory, at Grasselli Laboratory in Cleveland. We had another group there at the University.

I was given two or three people then after a few months, and was told to try to concentrate and select one of these processes as the one I thought might work. Well, we did select the basic one, but we couldn’t get the mechanical part of it to work. So then myself and the small group were transferred to Hanford, and told to continue to work and set up what equipment we wanted. They were pulling out of Chicago, and things were going forward.

When I went to Hanford then, I continued with essentially the same people that I had at the University of Chicago, and we started working there on this.

Groueff: You were in charge of the canning?

Grills: I was in charge of a group to—

Groueff: Solve this problem.

Grills: To solve the problem of encasing the uranium into a method – that it could be placed inside the pile and work there.

Groueff: Could you describe this bath and what it looks like? What dimensions, what your laboratory looked like?

Grills: Well, I would say it was a bath, maybe three feet in diameter and four feet deep with molten aluminum material of that kind in it. I don’t think I ought to comment what the material was, but just say it was a molten bath open to the atmosphere. Some of our baths were heated by gas heat, others were heated by electrical heat, just enough to get the material in a molten condition.

Groueff: Molten, yeah.

Grills: Yes. We had devised mechanical devices for heating and so forth. The point I’m making is we got rid of all those. We just picked them up with a set of tongs so to speak, one in one hand, one in the other, and do it. And there it is.

Groueff: Is it highly radioactive and dangerous?

Grills: Oh yeah. But you could handle—

Groueff: Protect it.

Grills: Oh, yes, you could handle it with tongs without a doubt.

Groueff: With tongs. Did you have to wear some masks or some—

Grills: Well—

Groueff: It’s not naturally hot?

Grills: No, it’s not that hot. The important thing is to not expose yourself. Of course, we had our health physics group, and we carried our badges and so forth. And then we got checked regularly, so we knew we weren’t being exposed.

Groueff: It looks like a very simple device, this bath: just an open, round bath.

Grills: Oh, yes, just an open, round tank. You just dip them in and—

Groueff: It was in the laboratory.

Grills: No. We had set these up out in what we called a canning area. We had set a plant up to do this with. We had a lot of these baths, because we thought that this was the way to do it. Well, when we got through, we just were able to get rid of all the “gingerbread,” let’s call it – the extraneous equipment – and just use the simple baths. Gather a couple of operators around each one and supply them with the materials, and they would work it together.

Now there’s two or three things that I haven’t mentioned that had to be done. You know, uranium oxidizes very fast. If you have you seen a piece of uranium in a slug form, it’s black and it will not take a coating until you remove this. Well, an interesting sidelight that might make an interesting comment.

I well remember at the University of Chicago the way you clean the uranium slug. You can clean it with acid, or you can scrub it off by hand. You can do it lots of ways. Well, one of the fellas one day – I don’t know who this was, it certainly wasn’t my idea – but one of the fellas said, “You know, I wonder if we sandblasted this thing, what would happen.” Well, at the University there – we were working in the old brewery building, which was over on the other side of the campus from Ryerson Hall – we did not have a sandblasting arrangement. So I got the purchasing agent to arrange for us to go to a company that had a sandblasting arrangement, whereby it was about desk size. You reach in and you can put anything you want to sandblast. For instance, you’re blasting parts that you’re going to paint.

We went up to the north part of Chicago, where this man had this piece of equipment. We said, “We’ve got some material here.” And we presumably were just university boys that they didn’t know anything. “We got something we want to blast.”

So the fella said, “Oh, sure. Give it to me and I’ll get the operator to do it.”

He had several of these set up. It was a commercial setting. He took this piece of uranium, and he put inside this sandblaster and pressed the thing. When sand hit uranium, it sparks like a giant sparkler. I thought the man was going to faint.

He says, “Oh my gosh! What’s going on here?” Naturally, we couldn’t tell him what was going on.

We said, “Just go ahead and do that, it’s all right. Nothing’s going to happen.”

So we cleaned these up. This was the method that we ultimately used to clean this off, because uranium here oxidizes. So you have to clean these off before you go dip them into this tank and do it. All I’m illustrating is that I’ve often wondered what this poor fellow in this machine shop must have thought. He was completely mystified. He had no idea.

Groueff: Was uranium or—

Grills: No, no. He had no idea what in the world kind of material. After all, he’d blasted on iron and he’d blasted steels and so forth. But he’d never blasted anything that shot sparks at him like a giant sparkler. I can’t overemphasize. This was, as I say, a piece of equipment about like this and the whole thing just filled up. Because uranium oxidized so fast, this is where the light was coming from. This guy really was shaking like a leaf.

Unidentified Male: He must have been surprised when he first picked that slug up too in the first place. The weight.

Grills: Yes, no doubt about it. No doubt about it. Because he said, “What in the world’s this?”

We said, “No, no that’s all right. Just go ahead.”

Groueff: Yeah, you couldn’t explain.

Grills: Yeah. I might tell you one other interesting thing. This is personal, but one time I was at Chicago and we were working with the people out at the Aluminum Company of America. I had to take two cartons of uranium slugs from Alcoa up to Grasselli at Cleveland – this was in Pittsburgh – to Cleveland, back to the University of Chicago. These were in long boxes about so long and about so wide, but you know, this is real heavy stuff. You know how traveling was during the war. I had my suitcase and I had these two things and they were just about more than you could carry.

I was in Cleveland in the railroad station. We didn’t like to let anybody handle these. In fact, we took them into the diner with us, and we took them all over. By gosh, you had this checked out to you; you better turn up with this amount of uranium! So I got in the railroad station in Cleveland, and a porter came rushing up to give me a hand. Well, I was worn out. I said, “Very fine.” He grabbed hold of these, and practically jerked himself off his feet because he couldn’t pick them up. [Laughter]

So then he had to carry them. If you’ve ever been to the Cleveland railroad station, down underneath, you carry it around and there’s a hotel up above. Boy, when I got there, he said, “What in the world are you carrying around here? I’ve never had anything like this in all my years of being a porter, you know.”

I said, “Thank you.” And gave him a nice tip.

Groueff: It’s heavier than lead, no?

Grills: Oh, yes. Oh, yes. Much heavier than lead. You have a piece this size and you pick it up, you just can’t imagine. You have to kind of struggle to get this up.

Groueff: It’s like a brick? A normal brick? It will be really—

Grills: Yeah. A piece this long, for instance. This kind of a size would weigh several pounds.

Groueff: Like about—

Grills: Well, let’s say an inch in diameter and 4-5 inches long. I don’t know how many pounds. It could be figured out. But it’s so unusual to find something as small as this to be so heavy. This was always the shock that we all had when we started fooling around with it.

Groueff:  The poor porter.

Grills: He couldn’t imagine anything being that heavy in that small of a little container.

Groueff: How old were you at that time?

Grills: Oh, gee.

Groueff: Forty—

Grills: I’m fifty now. I guess I was about 26 or so.

Groueff: I say, the whole group was very young, or you were particularly young?

Grills: No. I guess our group. This other fella who I mentioned, Ed Smith, was maybe 5 or 6 years older than I was. I guess we were all anywhere between 25 and 32, that age, in my particular group.

Groueff: As a scientist you were quite young. A beginning scientist, especially in metallurgical things—

Grills: I was not a metallurgist. The metallurgist, I don’t think it ever got solved. [Laughter]

Groueff: How did you have this idea, then? Did it come by luck? By chance?

Grills: No, I don’t think so. And I don’t want to claim credit for this idea. I said Ed Smith and I went out there together and did this.

Groueff: Yeah. 

Grills: I signed a patent on this one time, and it so it must be in the files someplace. I think this came about – and this may not sound right to anyone, and I wouldn’t want it to sound too corny – but it came about because we just kept working and working and trying anything we could try. We said, “The problem here is that we don’t have even heating on this, and we’ve got to devise a way to get even heat transfer.”

We finally decided we’ll just see if we can do it under the surface. When you put anything in liquid, it’s bound to be covered on all sides, and then it’s just going to be perfectly heated. Except where the tongs are, and we can shift those around. This was the best way that we could devise and think about. We said, “Let’s just try it, and see if we can do it and try it under the surface.” And we did.

Because in the other – we had electrical methods; we had [inaudible] methods; we had all kinds. This is pretty well known, I guess, in chemical engineering, but the way to get really complete heating of this thing would be to do it under any kind of a liquid. So it certainly wasn’t any flash of genius, or it wasn’t set down and reasoned out from any theory. I think it came about just working on it, and it was a practical contribution.

Groueff: Until then you tried more of the same thing, but above the surface?

Grills: That’s right.

Groueff: The molten whatever it is. So the real trick was to do it under the surface?

Grills: To carry out the whole operation under the surface. There was no way for air to get in.

Groueff: There were no air pockets or nothing?

Grills: We used to worry. You see, we’d get these slugs all free of oxygen. Before we could get it, we said, “Well, maybe this is a little place here that isn’t properly coated, because it’s quickly oxidized, no matter how quick.”

So we tried to do this in nitrogen to keep this from oxidizing. We tried all these kind of tricks, you see. So we said, “The best thing to do is to get it all cleaned up and ram underneath the surface before anything happens to it. Take the can down, put it inside there, put the cap on, and bring it out.” And this is what was done.

Groueff: When it happened, were you very excited? You and Smith?

Grills: Oh my, yes! Yeah. Yeah. We knew right away. We knew right away that this did it. Because we were able to make several of them right away, and before we weren’t scoring as well. We knew, gosh, if you can do it so easy, this is it. We knew it was it, and we were so excited that when we went home – and this was quite late—

Groueff: Did you report to anyone?

Grills: We put them to test the next day to see if they were all right. We knew they were all right right away, as far as being able to do it, but we didn’t know for sure it was going to test. But we wanted to get a quick test. Then we went out and made a whole bunch of them. We said, “We’ll show you really how to make them now.” We went out and nobody could believe that this could be done so simply.

Everybody said, “Oh no.” A few people, of course, wanted to mechanize it and so forth, but it wasn’t necessary.

Groueff: You reported to whom? Who was your—

Grills: I reported to a man named Kel Jones who’s in the company. He is in the metallurgical work. You know Kel? Kelyth Jones? Kel is in with Bradford [County] in the metal work.

Groueff: He was your boss?

Grills: Yes. An excellent man, an excellent metallurgist, and supported us in whatever we needed to do.

Groueff: All the people obviously were very happy there, because this hurdle was—

Grills: Yeah. Yeah. Everybody was very thrilled. Yeah.

Groueff: What university did you come from?

Grills: I went to Indiana University.

Groueff: Indiana. Are you from Indiana?

Grills: No. I’m from Illinois originally. I went to college in a small college, Monmouth College, in northern Illinois, and took a degree in Chemistry. Then I went down to the University of Indiana on a teaching fellowship, and got my doctor’s from Indiana.

Groueff: After your doctor’s, you went immediately to DuPont, a real job. So actually, that was your first job?

Grills: DuPont was my first job, yeah. Never worked for any other company. I don’t know whether you’re going to do it or not, but you might be interested in talking to somebody like Jones. Or I guess Charles Cooper is another man that was in—

Groueff: Yes, we have. I have him on the list. Yeah. So they were your superiors.

Grills: That’s right. That’s right.

Groueff: They had the responsibility of producing the—

Grills: Another man that I haven’t mentioned here is Ward Meyers, who is out in the engineering department. He was in metallurgy work at the time. He was one of my superiors at that time also. Any of those people can tell you this essentially same story.

Groueff: Was the Chicago group of scientists working also on this problem? Trying to solve it?

Grills: Yes. After the DuPont group went out to Hanford to work, there was a group continuing to work on another process involving even different materials for doing this job at the University of Chicago. Because after all – and I think you’ve already probably found – in the Hanford project, you didn’t assume that any one thing was going to work. You always wanted two or three different ways of doing it because you just couldn’t afford not to have one of them working. Which was good: I don’t think we would’ve ever done the job without that kind of a backing. I mean after all, in industrial work sometimes we’ll select two or three, but we’ll only back one. It’s all you can afford. In this case, you back all three of them and bring them all along at the same time if you can, and then pick the one. There was another group working on this at Chicago.

Groueff: Okay. But you didn’t work with them?

Grills: No. We exchanged reports. We exchanged visits. There was a group at the University of Chicago, and I mentioned the group at Grasselli — the DuPont Grasselli. Then that group and ourselves were together out at Hanford, so there was still only two then. First there was Chicago and Cleveland, and then there was Chicago and Hanford. 

Groueff: How large was your group at Hanford working on this problem?

Grills: I don’t know. Maybe four, five, something like that.

Groueff: Four or five. Not more?

Grills: Oh no, not a big group.

Groueff: But all the heat was on you at that particular time?

Grills: Yeah. I say, my group under this man Jones, and Meyers that I mentioned—they had two or three other people. They had people working in the lab studying various approaches, and they had some theoretical groups doing some calculations, and there were other metallurgical problems besides this one. And construction of things. This was all under Dr. Jones.

Groueff: Dr. Jones. Yeah.

Grills: We were all located there in the 300 – this term “300 Area” is undoubtedly something you’ve heard.

Groueff: Yes.

Grills: There were a 100, 200 and 300 Area. These laboratories and the work was done there.

Groueff: Were you about to be discouraged after months or weeks of trying without success? How long did you try?   

Grills: Well, I was on the project for a little over two years, and this was all I worked on the project. 

Groueff: For two years?

Grills: I went to Hanford in April of ‘44 and left there in April of ‘45.

Groueff: Five.

Grills: Because the war was over— wasn’t it in August of 45? Is that right?

Groueff: Yes.

Grills: Yes. So I was at Hanford one full year and worked on nothing but this problem. I’m not sure just what the date of this was, but it was simply either late one year or early the next year, because after that I didn’t stay out there much longer. It was obvious that the part I had was all right. I was transferred from there to a nylon plant down in Martinsville, Virginia. That’s where I was when the bomb dropped.

Groueff: But you spent a whole year at Hanford. Even before that, you tried and tried and tried, and it was unsuccessful.

Grills: Yeah.

Groueff: That was pretty discouraging, huh?

Grills: Well, yes. Although you figure eventually you’re going to get this. You have to. I guess we were discouraged because we knew that we weren’t getting our part done. It just seemed by this time it should’ve been done so that other things could be accomplished, and people’s attention could be put on other things. You didn’t like to feel that you were the thing that was holding it up. Not that we had the total picture, now. Again, I wouldn’t want to emphasize we knew that we were working on things for atomic energy and for plutonium. We didn’t know just how it was going to be used, or anything like that.

Groueff: You did not know about the reactor.

Grills: Yes.

Groueff: The pile. You knew, but—

Grills: Well, I knew what it was. I didn’t know the details of it, because a lot of this—and I had, obviously a lot of friends in this, like Dr. [Dale] Babcock. I’d worked for an experimental station before I’d gone out to Hanford. So I knew what was going on, and we had an occasion to meet the various people that came out there. Dr. [Arthur] Compton and people like that, and they were always interested in how we were coming along on this. 

Naturally, we were looking for an answer, but I don’t think we’d ever given up the idea that we weren’t going to come up with one. After you work on something for a while, you kind of get discouraged, particularly if you know a lot of people are waiting on the success. I tell you, though, that that got solved.

Groueff: But tell me one technical thing. There were at least two reactors before that. It was the sort of primitive pile in Chicago. And then, there was the Oak Ridge ones. Didn’t they have to have slugs with cans?

Grills: No, they had a different design than the other one that came out of.

Groueff: They didn’t have other cooling element. Probably that’s what it was.

Grills: I think that’s the answer. Yes.

Groueff: I think that the Chicago one had no cooling at all because—

Grills: That’s right. Yeah, that’s right. They had to stop it after so long and—

Groueff: So the canning is to separate the uranium from the water.

Grills: That’s right.

Groueff: But in a way, the heat will be—

Grills: Well, actually, there’s gonna be heat generated, and you’re flushing this water through there to keep it under control. If you’ve got a perforation in this, then you have a chance to contaminate all this cooling water you’re running through. If this gets contaminated, then obviously we were practically pumping the Columbia River through these piles to keep them cool. I mean this was one of the reasons of the location, right? Because there was a lot of cooling water there, and so you just couldn’t afford to contaminate this through a leak.

Groueff: Also, the cooling wouldn’t be perfect. The cooling of the district water, if there was some air between the uranium and the can.

Grills: That’s right. You could get an isolated hot spot, and this could cause you trouble. The way these would fail, incidentally, is they would puff up. After a while, you’re gonna have to push down these long rods to discharge them, because you’re going to have to extract from this.

Groueff: Yeah.

Grills: If this is going to puff up and not be able to be discharged, how are you going to get it out? If you don’t get it out, it’s going to keep reacting. Occasionally, a pile gets into trouble, and they have to abandon it. At least, you hear about this thing that’s happened since the project. So there was a reason to have it encased, to be able to run the water through, be able to discharge it, be able to handle—

Groueff: It had to be perfect.

Grills: It had to be perfect, yeah. This is the key. I mean, there wasn’t one or two failures. There just couldn’t be any. Whether there were ever any, I don’t know.

Groueff: How did you test them? Special instruments?

Grills: We tested them in high-pressure steam autoclaves, and subjected it to steam that would’ve penetrated this, and then it would’ve corroded and then it would puff it out. It wasn’t any doubt if you had a failure that it would puff. So we knew that we were supposed to be a certain degree of smoothness, and they had to be that way. There was no doubt of telling when you had a failure. It wasn’t difficult to find a reject.