View Full Version : Stainless fusing mold wall thickness

Ben Solwitz
03-09-2012, 02:12 PM
I'm planning on making something like these molds (http://www.slumpys.com/SlumpysStore/product_Lock_in_Mold_SS-600-611VGH11407VGH959VGH666VGH9VGH.aspx) that slumpy's sells. I'm primarily interested in just making a simple rectangular solid, maybe 3" x 3" x 12". If I line it with 1/16" or 1/8" fiber, how thick does the metal need to be? I was concerned it might warp at fusing temperatures if it was too thin so I purchased a piece of 1/8" x 3" x 48" bar to fabricate a mold out of, but the guy at the local hackerspace said it would be easier to mill with their mini mill if it were thinner.

Marty Kremer
03-09-2012, 07:56 PM
16 gauge. Can you get U channel instead? No milling, just cutting.
1/16" paper will be enough.

Ben Solwitz
03-09-2012, 09:53 PM
I don't really have a good way to cut it. I'm sure there are a bunch of metal shops around Brooklyn but I have no idea how to find one that would be interested in helping me with a project this small. The closest one I found to my apartment does high end stuff and I doubt they'd want to waste an hour or two on me for $50

I suppose I could cut 1/16" u channel 304 with a hack saw?

Ben Solwitz
03-09-2012, 09:55 PM
I might have a cutting wheel for my dremel that would do it, now that I think about it.

Ben Solwitz
03-09-2012, 10:09 PM
Went through the first page of google results and the biggest square channel I found was only 1.5"x1.5", lots of 6"x3" and 8"x4" and stuff like that. I suppose I could just buy two pieces of angle and overlap them?

How about 4"x4"x0.25" angle (http://www.onlinemetals.com/merchant.cfm?pid=30&step=4&showunits=inches&id=3&top_cat=0)?

It's the thinnest they make in that size, definitely not cutting that with a dremel or a mini mill. They have 3"x3"x0.1875" but that isn't much better.

Maybe go with 4"x0.12" square tubing (http://www.onlinemetals.com/merchant.cfm?pid=538&step=4&showunits=inches&id=22&top_cat=0) and cut a side off?

Bought some new reinforced fiberglass cut off wheels for my dremel from amazon, someone said they make quick work of 3mm steel so I am happy to give them a try for $10.

Here's some 4"x6"x0.125" tubing (http://www.onlinemetals.com/merchant.cfm?pid=19621&step=4&showunits=inches&id=238&top_cat=1) that might work well, it's $70/ft though.

Steve Lazer
03-10-2012, 05:02 AM
Ben for 16 Ga you are really looking at sheet metal - find a sheet metal or restaurant supply that will manufacture hoods, they will likely have 16 GA 304 stainless in sheets and be able to bend what ever size channel you would like.


Rosanna Gusler
03-10-2012, 06:10 AM
i would just buy them from slumpys. cheap enough, they do exactly what you want and......they are ON SALE

Ben Solwitz
03-10-2012, 01:14 PM
They are wicked expensive even on sale. $31 for 4 4.5"x2" pieces. If those are 1/16" then that is like $4 of stainless sheet, even at super small quantities:


You could buy one piece of 12"x12" sheet for $17.83 and make 16 of those pieces out of it, which slumpy's would sell for $120.

Rosanna Gusler
03-10-2012, 02:08 PM
i guess, if the machining were free. rosanna

Eben Horton
03-10-2012, 02:55 PM
thats capitalism for ya.. lesson 2 is to go ahead and make your own and sell them for less than slumpy's.

Pete VanderLaan
03-10-2012, 04:37 PM
i guess, if the machining were free. rosanna
And your time wasn't worth anything.

Ben Solwitz
03-10-2012, 07:07 PM
It's ok, that gets offset by the fact that learning how to use a new tool isn't worth anything. I've certainly never heard anyone around here lament the fact that no one wants to learn how to do anything themselves these days.

Cecil McKenzie
03-10-2012, 08:31 PM
You might try to find a place that does water blasting ( not sure if this is the right name for this method) with computer guidance. Those molds or dams look fairly simple and could be cut easily with the water blast method. I had a place make some orifices for an Eclipse burner with stainless about the thickness you are considering. The place I used had a minimum of $40 per hour. They cut I think 5 orifices and I had to pay the minimum of $40 .If you can't find a place there to do it the place here might be willing to work with you by phone . Shipping can not be that much on that small of an item. You have to be able to tell them exactly what you want or draw it out for them. If you definitely know what size you want for example you would not have to make them adjustable like the ones mentioned earlier. This would take less time to cut .

Pete VanderLaan
03-11-2012, 07:41 AM
It's ok, that gets offset by the fact that learning how to use a new tool isn't worth anything. I've certainly never heard anyone around here lament the fact that no one wants to learn how to do anything themselves these days.
Well, don't misunderstand me. I'm all for doing what you're doing. I just don't have any illusions about the reason for doing it being a money issue. I would not for example want to make my own Potassium carbonate but I don't mind making my own silver nitrate at all. I haven't made my own blowpipes in forty years but I do build my own grinding equipment for quality reasons alone. I think the reason for making it yourself should be because you can't get what you need from someone else who specializes in that item. The cane example is actually an excellent one. You can buy shitty cane or you can make good cane. Which will you do?

Ben Solwitz
03-11-2012, 01:34 PM
Sounds like I'm going to have to make good cane myself. I'm just surprised no one is making it commercially. I guess there isn't enough demand.

Pete VanderLaan
03-11-2012, 02:03 PM
Too many people need too many different diameters. Some want it cased in clear, some don't. Work it wrong and screw up the color, get blamed. Do it right, get blamed anyways. Having pulled cane for Dale, I would rather drive a subway train in NYC.

Ben Solwitz
03-11-2012, 02:27 PM
Any tips for pulling thin stuff? I'd like to try out 1-2mm diameter so I can get some detail without using 2 kilos of color. I've pulled a decent amount of thicker cane but never tried to pull 1-2mm in bulk before, just a few little stringers here and there.

Pete VanderLaan
03-11-2012, 03:23 PM
Having a partner on the other end with a torch is key to production. It's really hard in spaces where people are walking around. They inevitably are drawn to standing on it. Kind of like touching wet paint. I use to pull cane on the passenger loading platform at the old Santa Fe train depot. I would do it about 7:00AM when it was totally dead. . I was amazed at how often people would come out of nowhere and walk straight down it like a dotted line.

Ben Solwitz
03-11-2012, 04:24 PM
How big of a mass of color would you start with? Are you talking a grass burner to keep the whole thing relatively hot or a small torch to heat a part of it? I can imagine it would be much easier with a pot of color, gather pull gather pull...

Pete VanderLaan
03-11-2012, 05:16 PM
Pots are easier. You get spoiled really fast. When we are pulling cane from colder glass, the exact torch works quite well for keeping a constant heat on the gather. We usually have about 2lbs on the punty, no more. It depends on what you're doing.

Cecil McKenzie
03-11-2012, 07:18 PM
Try using an armature with rods about 8" apart attached to a pipe or rod that you can position on a stripping machine. Position something that you can heat up in the middle between the armature arms that you can attach the colored glass that is on your punty, back off so you don't get in the way of the spinning armature, then turn the rod on the stripper as you would if stripping a piece. You will get small diameter cane that is 8 inches long with little half circles at one end. The pieces start to fly off as the glass contracts and breaks but this problem can probably be solved with a little ingenuity like an armature with a little give to it. I made a contraption like this but didn't proceed on the design idea that I needed the cane for but it does work. It may be worth trying. I hope I described it well enough for you to get the idea.

Ben Solwitz
03-11-2012, 07:41 PM
Yeah I think I know what you mean, Pete mentioned coiling it onto a wheel and I had thought about trying something flatter.


Ben Solwitz
03-15-2012, 07:03 PM
Back to stainless fusing molds, I ordered 2' of 6"x4"x0.125" rectangular 304 stainless tubing (https://www.onlinemetals.com/merchant.cfm?pid=19621&step=4). It arrived today and I took it down the street to the nearest body shop and had them cut one side off (open it up), and cut it into three 8" pieces. It closed up a bit when he finished cutting the side off, so he and his coworker bent it back into shape with a big wrench and some vice grips. They did a pretty decent job, but they aren't perfect. He charged me $40 so my total cost so far has been about $180. The one in the front here is the first one I finished deburring with my dremel, it is probably the least square of the three. Sorry for the crappy photos, all I have is a phone.


Any way to square them up without spending too much? Otherwise I think I will just sort of shim the sides with fiber.

Ben Solwitz
03-15-2012, 07:45 PM
Done with the other two:

Ben Solwitz
03-15-2012, 07:49 PM
So the plan is to fill one of those up with a roughly square mass of cane/stringers, bring it up to full fuse in a kiln, let it cool off a bit, and then pick it up in the hot shop and pull it. Here's the schedule Marty gave me:

Bring them to 1100-1150 in 2 hours, hold for at least 30 min, afap to 1460 (depends on what glass you're using) and hold for about 15-30 min. Let it come down to 1000 just to get solid and pick it up and go for it! Anneal after you pull, even if you pull them down to 1/4".

I'm aiming to end up with a 4"x4"x8" mass after the full fuse, and then pull it down to 1"x1" or 0.25"x0.25" or something like that. If I were to pull 4" down to 1" it would be about 16 * 8" = 128" (~10.7') long. If I were to pull 4" down to 0.25" it would be about 16 * 16 * 8" = 2048" (~171') long. Might be a two step process, I suppose I could pull it 16x as long then break it up and toss it in the garage, and then pull it again. Lots of work.

(4 inches) * (4 inches) * (8 inches) = 0.00209754419 m^3 * 2500kg/m^3 (http://hypertextbook.com/facts/2004/ShayeStorm.shtml) = ~5kg.

Can someone make me 5kg of stringers please? Pretty please?

I can probably just jam some bricks in there to make it smaller, it's gonna be like $150+ of color per pull otherwise.

Cecil McKenzie
03-15-2012, 10:27 PM
I thought you were trying to make the notched kind that look like the inside of liquor store boxes. The reason I suggested the water blast method of cutting is it seems so clean and does not induce bending or distortion from the cutting process. Why do you want to start with a square form and not a round form?

Rick Wilton
03-15-2012, 11:05 PM
Why didn't you just use some cut up kiln shelf (mullite) and stand it up. You can have any length, width, change it any time. A lot cheaper, easier and won't warp like the stainless is likely to do after time.

Kurt Johnson
03-15-2012, 11:22 PM
Having full fused cubes of glass, I am wondering how you are going to keep the mass inside the U molds? I had to dam up the entire cube with kiln shelf slabs and fiber paper. I found out that at full fuse temps different colors moved at different rates and the whole thing was difficult to move to the torch and not crack somewhere.
A good friend who is a master fuser told me once that glass at full fuse wants to be round and 1/4 inch thick.
Something that large will not get to the same temp at the same time. Color on the out side will be flowing before the center, etc.. You could dam the ends and full fuse, but you will have distortion on the bottom layers.
Bullseye or Spectrum color would be more predictable as to temperature, if you use color bar stringers of different colors the flow will be a crap shoot IMHO


P.S. Google Glass Kitchen and see the amazing pictures they make with stringer. It's done in round molds with the photo in the bottom. Thread size stringers are inserted into the tubes and the whole thing is fused and later pulled down.

Ben Solwitz
03-15-2012, 11:39 PM
Yeah I was going to make the notched kind but Marty suggested getting some u channel, except I couldn't find any big enough so I made some.

I am planning on damming the ends with bricks.

I want square tiles so I can tile them easily in a repeating grid.

Maybe I will try it with kiln shelf too. It seems like the problem with fusing it with an open top is that the top will melt first and then the bottom gets distorted. What if it was elevated on thin shelf and the top was covered with some fiber? I think maybe it will heat more evenly with this stainless and a thin layer of fiber than it would with kiln shelf.

Even if this stuff warps, with a heat treatment and some pounding it will be good as new. Stainless is a pretty sturdy material. I was just reading an article about flattening sheet metal and I recalled that I have a friend that lives near Corning that does a lot of decorative blacksmithing. He's been trying to get me to come check out his forge and stuff for years but I haven't been in Corning much since I moved away from Rochester. I will have to give him a call, maybe he can help me straighten these and then I can go fuse a bunch of stuff at the studio. They have some small wheeled pickup kilns that would be awesome for transporting 5kg of hot color to the hot shop.

Pete VanderLaan
03-16-2012, 07:06 AM
Kurt's observations about the different slump points for each color are spot on and his friend's observation about glass wanting to get round are on the money too.

As Fritz used to say "Glass loves to Ball".

I can certainly tell who's going to want to be pulling stringers night and day in the class.

Tom Fuhrman
03-16-2012, 10:28 AM
so, another idea: Buy sheet glass 96 coe glass from spectrum or Uroboros and cut it into strip and then use them to make your different patterns instead of round rods. It also doesn't trap as much air between them when fusing them together and they don't have a tendency to slide as much. I also would think it would be a lot cheaper in the long run. I can cut a lot of strip in a day and not bother with annealing, heat, waste, and sit down most of time I'm doing it. 1/4 strips are easy. You just might have to have a fairly large gather to encase and finally pull to get the fine detail that you want.

Pete VanderLaan
03-16-2012, 10:47 AM
Kind of a "Lego" murrini.

Ben Solwitz
03-16-2012, 12:18 PM
Yeah we did that in the rollup class I took Tom. It worked well but the Bullseye colors aren't too dense, and while I haven't used the uroboros stuff I bought yet, people say it's not very dense either. You can really tell when you look at it next to gaffer cane. This plate is made of bullseye, we made the canes the way you just described:


Those ones in the middle were quite thick and still ended up pretty see-through. The plate thickness is 2 layers of clear plus a bunch of cane laid on top and full fused. It is pretty even, but not quite, and measures about 3/8" at its thickest. Working with Bullseye in the hot shop also kind of sucks, it's pretty short. This is where Franklin tells me to shut up. Note that in the approximately 4 years since I took that class, I still haven't rolled up this plate.

I will have to builld some kind of stringer puller before the color class Pete. :)

Surface tension is only so strong, it's certainly not going to ball up a 4"x4"x8" solid. If you're suggesting that I won't be able to keep it square for the pull, I think you're wrong. Here is part of a rectangular pull I did a few months ago, not perfect but it's probably the 4th or 5th rectangular pull I've ever attempted:


That is made of 3 clear bits with a different color frit on the outside of each. Sort of a prototype, didn't want to waste a lot of color.

As far as the colors melting at different temperatures, I am well aware of those issues. One of the plates I rolled up had a big solid blue layer on about 1/3 of it and it was quite interesting to try to make into a vessel. I will probably start out fusing a bunch of clear cane/stringers with a few colors interspersed so I can see what the bubbles and distortion look like right after the full fuse. I may try to mitigate the problem by using only opaques or transparents together, if I can get the results I want that way.

I am anticipating that due to the maximum density packing of circles in a plane (http://en.wikipedia.org/wiki/Circle_packing), the height will be reduced to at most 0.91 of its initial value during the full fuse, probably less than that due to non optimal packing, which will distort the image by compressing it vertically. This could potentially be avoided by making square cane/stringers... :)

Speaking of squares, I love Alex Brand's Pagoda vessels (http://www.masterpieceonline.com/title.php?ititlenum=10029578&galleryId=11D8-FFGH-6E59&bc=).

Kurt Johnson
03-16-2012, 03:44 PM
My biggest problems were mixing transparent and opals in the same block. Because the transparent was so much stiffer (less viscosity?) I could never get the pull to be even. Your test with the three colors is mostly clear with frit. My pulls that worked out best were all opal or all transparent. I tested each color before hand to work out any chemical weirdness.between the colors.
I did not mean to suggest that your block would ball up, but by the time the center gets to temp the bottom and sides of the large mass will look like ice cream on hot pavement, all sort of mushed together.
I would think you stand a better chance of molding upright in a tube, and using a smaller size. The weight will not hurt you as much and you can always slice off the bottom part and still have a nice block to pull.
I some times cold worked the cubes after I cooled them to remove the kiln wash, fiber paper crap on the outside.


Ben Solwitz
03-16-2012, 03:49 PM
How thin do I have to get the pull so I don't have to worry too much about thermal shock when I put it away? It's going to be square. You guys said I need to anneal it even if it's 1/4" but that would be a 171' pull for a full mold like I said earlier. Supposing I did a 171' pull, I'm not going to get it into the box in a timely fashion.

I've been editing my last post a lot Kurt, I actually just added something about trying to use just transparents or opals. Another possible mitigating factor is that if they are interspersed and there aren't large areas of mostly transparent or mostly opaque, their viscosity should sort of average out. You run into problems when one large form is transparent, and another large, potentially nonuniform, section is opaque.

I'm planning on not annealing the block if I do a full mold because it will be 4"x4"x8" and take forever to anneal and reheat properly. I'm going to try taking it from the fusing kiln at 1000 degrees or so, straight into the hot shop.

The vertical fuse is definitely an interesting idea, I could buy some 4" square tubing or sheet and cut it to 4" lengths or something like that. You said I should go smaller, how small? It's easier to pull something that's roughly 1x1x2 in my experience, it's harder to get even heat into a cube, for example.

Kurt Johnson
03-16-2012, 04:36 PM
I did not read your post well enough, sorry.
As far as size goes, I was thinking about a shorter length up right, 4 inch in a 2x2 tube. In most of the murrini work that I have seen the pulls were incremental to the final size. First you pull a 2x2 to a 1.5 x 1.5, usually cut hot and then into a kiln. I would get more control over the final shape that way. Also the distortion is less between different color flow rates.
I pulled different shapes and I was taught the key to good shape retention is an end cap (crappy clear) in the same shape as the rectangle or triangle or whatever. Also you do not waste as much of your picture from the pulling.
I don't get the hot pick directly from the fuse, I always had to use some kind of kiln wash or fiber paper in the mold and on kiln shelf blocks. At full fuse the glass will stick to stainless very well.
I used mostly Spectrum sheet glass exactly as Tom stated above. This allowed me to use neat stuff like Pete's color and Gaffer color bar on the final piece.

I will have to admit that it was a lot of work, but a lot of satisfaction and fun.


Ben Solwitz
03-16-2012, 04:48 PM
I am planning on lining the stainless with fiber, and expect that the fiber will probably be pretty stuck at 1000, anything I can do about that? Small incremental pulls make a lot of sense. I plan to pick it up onto a relatively hefty post that is the same shape as the end of the block, and then add a clear handle to the other end, it sounds like it would be good to fully encase both ends in clear, which also makes a lot of sense. I noticed on that rectangular pull I posted a picture of that there was a lot of distortion at the far end because I didn't cover the whole end in clear, but it wasn't too bad because the pull was mostly clear anyway.

I guess if I'm going to add a big chunk of clear to the end then the fused block itself doesn't need to necessarily be 1x1x2. I can see how adding a big clear 'handle' would make it easier to pull evenly.

I'm trying 1/16" fiber paper at first per Marty's suggestion. He said it would come out easily when cold, I guess I'll find out what it's like hot, I have some 1/8" as well. This is why I'm not starting with $150 of color.

Looks like there are a decent number of sheet metal shops around but none of them have websites, not surprised. I will have to call some on Monday.

Ben Solwitz
03-16-2012, 07:19 PM
I figured out how to make stringers:


Perhaps I can order some non-zero dispersion, cobalt core 8 micron stringers.

Kurt Johnson
03-16-2012, 08:10 PM
Short of cooling it down and washing, I suppose you could try and sweep it off like they do on a pick up. Perhaps a little fire polish like David P. does before you case it. Remember that the layer ( micro bubs, fiber particles) in cross section may be just about invisible after you pull it down.
I never tried to remove one hot so I don't know about a possible expansion problem between the steel and glass.


Ben Solwitz
03-16-2012, 10:31 PM
The fiber should buffer it a bit since it's soft but I don't know if I might need thicker than 1/16" to get it out easily. I suppose I could look up the lec of 304 stainless.


Glass: 3-9
304 Stainless: 17.3

I think that means there should be even more space when it is hot.

I figured at the very least I would brush it off with a broom, while wearing a dust mask of course.

Is kiln wash any less sticky at that temperature?

Kurt Johnson
03-16-2012, 11:00 PM
Kiln wash would be harder to get evenly on to steel, and if it does stick to the glass it's a bit*h to get off. Fiber paper just sort of falls apart into dust.

Marty Kremer
03-17-2012, 08:36 AM
Ben- The steel will contract (faster and more) than the glass will on cool-down. You need a buffer or gasket like fiberpaper (not thinfire, use 1/16 or so) to allow you to pull the glass out.
You should be able to brush it off after pickup but do it in front of an exhaust fan or vacuum- the airborne dust is a longterm respiratory irritant (think of silicosis).
Leaving a slight angle to the sides of the trough will make it easier to get the glass out.
As far as using strips instead of rods or stringer- that depends on how you want the result to look. If you're pulling a 3"x3" down to 1/4", it's not going to matter- you won't see it.

That bit about soda lime glass wanting to be 1/4" thick assumes no wall constraints: a 1/8" piece on a kiln shelf will try to get thicker, leaving holes. A thicker piece will spread out (given enough space, time and heat) to 1/4".

Sandy Dukeshire
03-17-2012, 09:25 AM
Hey Ben - check this out - vertical fuse in steel - perhaps you can get some ideas here. Mark is a great guy willing to share.


Ben Solwitz
03-17-2012, 10:54 AM
Very nice, thanks Sandy! Is he on here or yahoo at all?

The lec is much higher for stainless so it will expand more when it comes up and shrink more when it comes down, right? I guess the glass is going to try to fill it at ~1450 though. Would 1/8" paper make it any easier to get out? I have some of both.

I don't want to put it in the hole too much before brushing it off, but I guess it shouldn't be too susceptible to shock because the core will likely be quite a bit warmer than the outside when I take it out of the kiln.

Sandy Dukeshire
03-17-2012, 01:18 PM
Mark is on facebook and i think warmglass.

yes, the glass should fill in at 1450, but would you not want to let it cool a bit before removing, to say 1200 (or just below softening of whatever glass your using) to keep things in order? this temp will give you enough time to clean things up before going to the glory if your quick. and i do think the glass will be less sticky so your fiber is not embedded.

and why not use 1/4 inch fiber? it will almost peel off as a sheet, will give you more wiggle room, and its not as messy as thin fiber paper (but yes still do it safe...)

Ben Solwitz
03-17-2012, 08:58 PM
Yeah I meant I would have to cool it down so the metal is going to shrink a bit before I try to take it out. I bought some 1/16" because Marty said it worked well for him, and I got some 1/8" in case I needed some more wiggle room. We'll see how it goes, maybe thicker fiber would be easier. I would like to use the thinnest possible because I don't actually want it insulated.