Mark, I am wondering if I chip out a graphite block if I could lay a piece of glass over it and whack it with a flame until it melts into shape, remove and toss in the kiln. Kinda like this procedure. I cant put the graphite directly in the kiln at glass slumping temperatures as it will fall apart. It's good for short term heat, just not an extended time. Remember this?
Graphite is still pure carbon, it's going to burn like coal without an inert atmosphere. What about grey cast iron with a graphite coating?.... Oh wait: I remember a friend slumping glass to make a Maksutov telescope corrector lens who had glass stick to a cast iron form in a furnace.
Yup... almost got it now! I'm taking this secret to the friggen grave with me! Still not happy with the final thickness, so I'm running a plaster sample pressing tonight and can use that to tell me where to add to the pressing tool. Turns out, I was having a draft issue and the glass was locking onto the pointy bits! More testing tomorrow... or is that today? I think I'm going to take the chicken shit way out and make a crap load of these all in green and stick it in the shade. I'll get more tricky on the next one. I'd like to get this cast sometime this YEAR!
WTF OVER? Got brave and skipped out on coating the mold with boron nitride. Now this is one seriously weird failure. Odd thing, the side in contact with the mold smoothed completely over. Still not sure how that one happened. I got it hot, pulled, pressed and hit with air to firm it up. I then tried to get it off the mold still up at temp. I couldnt. It was stuck hard to the bronze. Back in the heat for anneal and strain. Only way it released was back at room temp. Looks like the glass removed some part of the bronze? REALLY weird.
Play it again Sam! If this one F's off into the rhubarb like the last one, I'm just going to have to make the mold out of graphite. Cleaned back up again and applied 2 light coats of boron nitride. Trees have red leaves right? (I ran outta green) I cut the glass a little short because at forming temps, glass will ALWAYS seek the same final thickness. I'm hitting around 770c, pulling the show outta the kiln and pressing it, whacking it with some compressed air to firm and will TRY again to get the mold off of it and just get the glass back in the kiln for anneal. My thinking is the bronze holds heat WAYY longer than the glass and might be fighting my glass. Also, I've never seen anyone aneal glass while still in a mold. Molds do not typically go inside kilns unless you are casting glass in them. I don't consider this casting. Forming, yes, casting no.
This is utter madness! The bubble part never made contact with the mold. The glass there is the same thickness as the rest so I suppose that means I've got the pressure right and the two pieces of glass are only slumping and not running. I was able to remove from the kiln, press, blast with air and flipped the mold over onto some wood and got the glass outta the mold. I hit it was some more air and back into the kiln. The plaster model I ran yesterday came out with an even thickness right at about 1/4". The shine is nice, but this just never got the impression. Odd that the square base didn't fully form either. Anyone got any bright ideas or am I just screwed on my own.
Possibly, but the last 3 were all done at 750c.. Keep in mind, if it's too hot, it pools down in the hole and ends up thick. Then it turns dark with light behind it. I might add another layer of bronze on the tamper tomorrow and try yet again. I ordered a graphite block tonight. I bet that crap is a mess grinding it.
Total insanity... Still waiting on graphite to show up I'm tempted to cut the graphite on the neighbor's cnc.. hmmm
Have you spoken with him about that? It gets everywhere and the dust is an absolute electronics killer. Best, Kelly
Definitely a difference in the heat expansion between the two materials. Possibly heating the mold would help release the glass but I have never worked with glass so I am just guessing. I have seen this done with other materials at a lower temp and they used a vacuum to pull the material into the preformed shape.
it's weird. I get a different failure every time. I'm running a ramp and soak controller with the same schedule. Honor nitride coated bronze. Sticks sometimes, other times, drops right out. COE of bronze is 9 and this glass coe is 96. Glass should shrink away from the metal and into the cavity. frustrating.
WOW. Graphite is REALLY nasty! It does machine really easy. I think I'm going to do this wearing a trash bag in the back yard with a dremel and a big fan blowing on me! On another front... Got a package today in the mail. This was using a very large came. I know this has been an epic thread and it's taken literally 3 turns in methods. Casting, Dalle de verre and also pressing. All of it has taught me some very valuable lessons. Below is a photo of what started all of it in case you forgot. In that photo, the came surrounding the Dalle de verre pieces is seen. I still need to sort out the lead work method, but it's pretty close to what these guys did 110years ago! The question will be how to properly flow the lead between the pieces and keep it from lipping the came. In my 4 piece sample here, I spaced them very tightly so that's probably what's going on. For now, I'm counting this a major WIN!
Your sample piece is going to look colourful compared to the last photo with it's large gaps filled with solder, your tightly packed chunks will be easier to solder with capillary action holding the solder in place until it cools. That last photo shows some smooth solder, they probably had one of those old school copper block soldering irons heated over a flame with plenty of thermal inertia while it's being soldered. Ebay has some 100/200/300 Watt soldering irons that would be good for the job, I bought one for lead filling some car panels. https://www.ebay.com.au/itm/100W-15...hash=item2cfddb52a4:m:mfBr1_MWpPOEqIPbc46xxDA
Very true Mark. Tighter together will be great for embedding in the bronze as a matrix. The wide gap in the photo is of a lampshade that has a 15" diameter. Less pieces and less work that's for sure. I've got one of these bad larrys. If I get this within 10feet of this lead, it will be running down the driveway. 550WATTS of madness! Hexacon 550p
That's not a soldering iron!, more like a South American government issue torture device. It would be extremely difficult to get solder to bridge such wide gaps when fluid without some kind of support and besides you want to get the glass in position to get an idea of the finished item rather than having to build it first to see the appearance. If you compare the solder surface of your test piece: it was pretty hot to get such a smooth surface where your test piece's surface is rougher due to cooler soldering.
Yeah, I kinda F'd up when I bought it one night on ebay. Might have had a few too many beers. I think it's really for roof lead work. I paid 40bucks for mine, new they are SUPER expensive.
