Topic: Follow-up questions with Gaffer™ Glass founder John Leggott. Comment: I just switched over to Gaffer™ Batch. What a great glass! Everything about this glass is good. Virtually dust free pellets, nice (lower) working temperature, faster melting time than batch, reasonably long working time, fast reheats, good body and surface tension. Another thing I like about this glass is that it contains neither Barium, Lead Oxides, or Fluorides making it less corrosive on the refractories, and less toxic flue emissions. I highly recommend this product. - Peter Greenwood www.petergreenwood.com Question: Gaffer™ Glass - Is there any difference between the Gaffer™ glass being manufactured by Phillips, and the Gaffer™ glass being manufactured by Seattle Batch? Answer: It would be the same recipe. There may be differences in the manufacturing prices. Phillips is not particularly forthcoming on exactly everything involved in manufacturing the batch, but essentially you are getting the same recipe. The pellets may look slightly different, they may be slightly different moisture content in them, but the recipe will be identical. John does that change if you go from 1980 to 2050 you are going to be a little bit more stiff as far as workability, it depends on what your making right? It does depend on what you are making. I mean, if you are wanting really hot glass for doing nerds on Italian goblets, well then you'd run it hotter than if you are doing large work. I mean it is pretty hard to be categorical about working temperatures. Everybody's got their own taste. It depends on what you are making, I mean that is pretty much a matter of preference really. I believe that Phillips' is putting erbium in their batch but Seattle Batch hasn't. Seatle Batch is using best quality Oklahoma sands. For people that want a very clear glass, I am sure they could add erbium if they wish. Question: I am currently using SP87. I melt it at 2225, has been working fine, no real problems. I work it at 2050. What temp. do you melt gaffer and what temp. do you work gaffer? Is it pretty clear, does it contain erbium to clean it up like SP87? Is gaffer compatable with the other color manufacturers? Answer: Now the next question from Ed Kozlowski, Ed you are currently using Spruce Pine 87, which you are melting at a 2,225 degrees Fahrenheit. I don't see any reason why Gaffer™ can't be melted at the same temperature, we recommend a hotter temperature than that but that just means it is going to melt faster. According to the viscosity data that was done on Spruce Pine, at melt temperatures it should be more viscous than Gaffer™, so therefore I would suggest Gaffer™ batch should melt easier for you at those temperatures. I notice you work at 2050. A lot of people are working Gaffer™ at 2050, we found it can come down to 1990 and it's pretty easy to gather. Question: I forgot to mention that I am using a Denver 135# electric furnace. I don't believe I would be able to melt gaffer at 2400 degrees. I really don't want to push the elements, kinda costly and I just started to get a decent life out of them. What temps. do you reccomend for the gaffer? Answer: The ones that I have seen (and they may have changed this) but as far as I know, most Denver furnaces use a wound element like a kanthol or super kanthol element or maybe a nichrome element. Those elements you can you can get them up to 2400 degrees but their life span decreases dramatically at that temperature. Not to mention the fact that if you have any kind of alkali or corrosive dust in your atmosphere here, it could potentially get near those elements and further reduce their life. It's kind of not recommended if it can be avoided to use to be melting a batch in an electric furnace like this at that high temperature, it can be done you just have to be prepared to change your elements out, probably a little bit more frequently. I am not exactly, I couldn't say exactly sure since I am, I haven't had direct experience with melting Gaffer™ in that furnace but that is an issue. It is a problem with electric furnaces that are based on that kind of a design. I mean the other type of electric design would be like a MOLY-D type of element or something like that or like the glo bars. Those are also affected by that, they are much more capable of going up to high temperatures. You just have to have enough energy to get them up there so, and you may want to do something to make sure that there is no dust coming off your batch. It sounds like the Gaffer™ Batch is probably a lot less dusty than any of the other batches that I have seen or most of the other batches, especially Spruce Pine, and the Spruce Pine, that type of a furnace was especially a problem. Potentially, the dustier the batch is the more potential you are having of creating a film on everything, the walls, the elements. The dustier it is the better the chance of destroying things just because you are adding flux to the walls and especially the elements tend to attract it, even more because they are the hottest spot in the kiln and they are really affected by it. Question: I'm not sure I can make the conference call tonite, but,I would definitely be interested in your suggested topics, particularly the different types of stainless, scale problems and the cure, and tool maintenance and construction. Answer: I guess I would start by saying for all of our, we use two different kinds of stainless in our stainless pipes, we make our heads out of a 310 stainless and the bodies from almost all 316 and we use a 316 because it is a little bit more resistant to heat corrosion and scaling and it is also a little bit stiffer than the 304 alloys. So those are the primary different types of stainless that we use. The 310 is really great stuff, it's got a little bit higher nickel content which gives it good heat resistance. And it scales much less than any other reasonably priced stainless steel. You can actually get stuff that's a little tougher than that but the price starts to get out of, it gets extremely expensive. It would be more like a hastalloy or inkanal type of material. The 321 is actually another grade that some people have tried. One of the problems with those is you increase your nickel content as they start to get closer and closer to the, to being compatible with the glass as far as expansion goes and sometimes with those alloys the glass doesn't crack off as easily and you can wind up with either big glass buns on your pipe that don't want to come off, so and for the most part the 310, we've had such good success with it I just don't see any reason for going to something tougher because it really does, it lasts the life of the pipe, the head is not on these pipes, the ones that we've done with 310, the really the heads, we haven't seen heads falling apart or scaling apart, so I think that that is, I am pretty sure that we found the right material there, it is a good balance of economy as well as durability. Question: My question has to do with hot shop design. In designing the ventilation hood for a hot shop, is there some formula or guideline that can be used to size and locate exhaust fans to move the amount of air necessary to maintain a comfortable environment on the shop floor? Answer: First off, the first question that I can see that seems to be specifically addressed to, the fairly clear question has to do with, it's from Paul Abbot and he has a question about hot shop design and he asked in designing a ventilation hood for hot shop is there some formula or guideline that can used to size and locate the exhaust fan, the movement amount of air they are necessary to maintain a comfortable environment on the hot shop floor. Which is a very interesting question, something a lot of shops struggle with, and it turns out the thing you need to know is essentially how many BTU's your equipment is producing, for example, a glory hole that gives off 200,000 BTU's when it's on full or maybe 75,000 BTU's when it's idling. If you know that number or have a pretty good estimate on your BTU's you can calculate that the formula basically is 1.8 BTU's increases air temperature 100 degrees in one cubic foot of air. So you can use that, I actually have a little calculator that calculates how hot something will make a space, if you know the size of the space you can calculate how hot a glory hole or a furnace discharges. You basically want to keep your temperature under, say 100 degrees and then work out the numbers, but to get, if that person is specifically interested in this calculator they would probably need to get ahold of me directly and I could e-mail them. It's a, it's an Excel calculator that calculates temperatures. So it is something he could use on his computer, anybody could use, and, but they would probably just have to get me their e-mail address and we would go from there. But there is a, there basically is a formula and a guideline for determining the size of the hood, now as far as locating the exact position of the fan that's a, it's a little bit more tricky, I mean people will locate them mostly where it is convenient in the shop. Obviously above the equipment is better so, you would just have to see something a little bit more specific on that. Question: I have a client who would like to have an itemized list of what gaffer color does not contain lead. Is this possible and if so could you fax it to Olympic Color Rods and I will get it from them. Answer: Olympic Color Rods has the information. You can call at anytime and they will fax you the lead content of our color. All the OPALS are lead free, except ones based on gold, which are Gold Pink and Heliotrope. The reds and yellows in the Transparents don't have lead. All the other colors do. Question: John, the difference between the Spruce Pine and the Gaffer™ batch, is one is using a silica powder, versus a silica sand and if you could go into the differences and how that affects the glass. Answer: I am not that familiar with the mesh sizes of the particular sands that both companies are using, so I can't comment really. I have heard that Spruce Pine is using virtually a flour of 300 mesh, that seems over the top to me I mean 100 mesh is perfectly adequate for melting quickly. What you wouldn't want in there is grains that start getting down to 20 or 30 mesh it is certainly going to take longer to melt them to the batch. But I am sorry I don't have the exact specs on both companies grain sizes to comment accurately. As far as I know people are not having any problem melting either Phillips or Seattle Gaffer™ batch in their furnaces, just a point here for Ed, he asked if Gaffer™ was compatible with the other color manufacturers. We certainly don't want to be out in our own universe. We definitely want to be making color that people can mix with German and Czech color. But I would suggest that the German and Czech glasses aren't often compatible with themselves whereas we are. I think the closest match for us would be with Kugler lead transparents, Kugler items seem to be lower than us, and currently red and yellows are definitely lower. The same goes for Reichenbach, especially their reds and transparent reds and yellows. Question: Now I know, I know we talked about this on the last call and I kind of wanted to follow up on two things but when we are talking about the viscosity of your glass and how if we were to take a range let's say of, of a Kugler or another company that the range from a yellow in an opaque or even transparent in a cobalt is much wider than the range of your two glasses. Could you kind of go into that and explain why that is. Answer: Well it is not really possible to make the entire color range with the same viscosity. Basically our transformation temperatures would range from say 840 Fahrenheit up into maybe 970. So you've got a spread there of 130 degrees Fahrenheit in the annealing temperatures. I believe that our red and yellow transparents have a lower viscosity than the German equivalents. So I would suggest their spread is slightly wider than ours. I would suspect that their transparent reds and opal yellows possibly go up to as high as a 1000 Fahrenheit. For the annealing point, so their spread could be another 40 degrees Fahrenheit more than us. Now is that as a result of using potash versus soda? Is that why that is? No, not really, it is the result of probably using barium rather than calcium in the transparent reds and the same would go for the opals. Question: Can you talk about your annealing temperature for your hot box and how your Gaffer™ Color is affected by that. Answer: I know earlier you were saying that I should talk about fact that our opals need to be run fairly hot in the hot box before they are picked up. All our opals apart from the gold pink series, have no lead in them, and so if you are running like a Kuglar opal blue with our opal blues then their transformation temperature is lower than ours. And if you have been used to picking up Kugler opal, blues and greens, say out of the box and they haven't cracked, then you would need to run our opals hotter. Often you can't hear the bar cracking when you are transferring it to the glory hole, then when you go to blow it out there will be a lot of little bubbles from where the crack is sealed. You really need to be running our transparents and our opals at different temperatures in your color box, but you can achieve that with a garage obviously. Question: Could you talk about the yield of your Opals versus the other companies , and how the yield is greater. Answer: Glass Blowers are used to buying their color by weight, but actually as the manufacturer we think in terms of volume. Now obviously, the denser glasses as you put more and more lead into it, you are getting more weight per volume. Obviously, we like that idea as manufacturers, but when you look at something like comparing our opals with the German opals, our opals would weigh around 2.5 grams per cc. The German opals would weigh 3 grams per cc. So what that means is that if you buy a kilo of our opal and a kilo of Kugler opal, (I am talking blues and greens not reds and yellows here) you will get 20% more volume when you buy our opal, compared with an opal that's got lead in it. We are not talking volume in terms of color, we're talking the volume of the bar. It is not a question of density as much it is volume. I mean obviously, if enamel white has 50% lead monosilicate in it, it is going to take a much shorter bar to weigh a kilo than Opal white, which has no lead in it at all. So you are getting a lot more volume of Opal white per kilo than you are of the Enamel white. Question: What currently are you working on in Color? Answer: Color-wise, this is the year for us to cover browns, grays, tans, ochres, from all that part of the spectrum that we haven't really addressed before. We are testing all opals, which we are working on at the moment. The tea color that people want in transparent, people are wanting a grey transparent, so that's our main focus color wise this year. To stay abreast of our colors you can always check the New Arrivials section on the OCR website. I think we can polish it off with another 15 colors. We've got three to go on the lusters, we have to do a green, a purple and a clear and then that's the spectrum as far as the lusters are concerned. We've just done two more transparent yellows, before we just had Citron and Saffron. If you can imagine Citron has no selenium in it at all, and Saffron has quite a bit, so that it is that orangey looking. We've done two yellows with a logical progression of the selenium to fill that part of the spectrum. Those colors are G-76 Yellow and G-77 Daffodil which are currently available. Question: Have you added any more pots or tanks to beef-up production? Answer: We just put in another whole section that will be mostly dedicated to making casting crystal. So in terms of melting capacity we have just gone up about 60%. We have dedicated other tanks for color rod all the time, so there will be two teams making color rod and a separate team making casting crystal. Question: Why would anybody want to use the carbon steel pipes? Answer: Well as far as the body is concerned carbon steel is really actually rather popular on bodies, and one of the reasons is, is that it feels good, it is not slippery, when it's a hot day and you are working with larger pieces, your pipe won't slip in your hands, it really, it gets a little bit of rust and the rust pits the surface a little bit, so it's got a much better grip to it. Sort of a natural grip and it's just that people really like the feel of it. It is the type of thing that has to be kept clean because the rust can get out of control but for the most part you are going to have to live with kind of a brownish, a dark brown pipe, but they can be cleaned with Scotch Brite, works really well and I think, you know some people have actually taken a little bit of beeswax and put it on their pipe and once you do that you don't really I don't think you really have to do it after that. Once is just about enough. Beeswax seals it up. Seals it to air but it will always mean, it will always maintain the grippy feel. The pitted feel that you get from the steel. One other thing about the steel pipes is that they are stiffer, they are considerably stiffer than the stainless steel, so bending is not as big a problem. Actually one of the stiffest pipes that we have we can just barely straighten it. It's so stiff and it's a steel pipe and it's a, it's our XLS. It's a straight steel pipe and it's incredibly stiff. , it's so strong that you can literally stand on it between the rails, they are tough pipes. And another thing about the grip that Fred was talking about is with the stainless, it is so soft that you can't keep a grip on it even if it's been brushed it wears off where as the steel is a, holds its brushed finish for quite a long time. It's a give and take, you gain something, you lose something , and you just need to figure out what you want. It really depends on how the person works. And one of the things we always tell people is not that there is one that is better than the other, some people can really pick, they really like the, and it is especially true of the professional, the people who are blowing every day, day in and day out, they seem to like the steel pipes quite a bit, and I think it is largely because of the seal but they also have to contend with the, all of the issues that you get with the steel, which is the rust and it scales easy, more easily than the stainless, but if you are doing lots of production or really doing the same piece over and over, in a more of a production setting, the stainless can work quite well. Question: I have a question regarding some control that I saw on your glory holes at Corning. You had a nice cable thing for the air and text you could adjust reduction in heat from the front of the shield and I was curious is that something that you made up or are those parts available that you can buy. Answer: That was a special request item from Corning, and if that's a, I don't think anybody's actually ever noticed those before, they turned out to be almost more difficult to make than the glory holes. Although once we figured out how to do it, it wasn't too complicated, it's just a, it's something that we machined here in our shop so it requires a little bit of machining and a cable assembly and other than that it's mostly off the shelf bicycle type components. Cable on the cable sheets, but they are not very easy to build I will have to say that much, they really turned out to be a lot of work. All right, if you have a chance to get to go back to Corning of course I would highly recommend just going back there and studying them, seeing how they work, one of the wheels on one side is larger, the wheel that drives the cables on the side with the dial is a smaller wheel than the wheel that attaches to the butterfly valve. That's not something that we normally build or something that is easy to make out of stock parts. Question: You had mentioned that one of the people making up your batch put erbium and one doesn't, did I get that right? Answer: I believe that Phillips is putting erbium in them in their batch. Erbium is a particularly stable chemical that can't be affected by anything that is why it is so useful as a decolorizer. Because it is completely bomb proof from a reduction or oxidation view point. |
