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I do almost only castings. I like the glass clear, and use the pilt (scrap) glass from a nearby glass factory. It is cheap, has a COE xx, but if it is from one melt, it is self compatible. I crush and wash it, buy colored frits from the same manufacturer as that glass factory. Works fine for me. -la...

Charlie commented: i use talc on the bottom of my pot melts, and it never sticks. it does make the back lumpy though, as it moves with the glass movement. this makes me wonder if talc could be used as a kiln wash if applied in a water medium though. Try it and tell the results. I have used AlO slurr...

> The kiln wash is OK well above 1000 c > But its the glass that wets the wash so it sticks more as > temp increaces > > Avoid enamels / fluxes near wash n fire slow n low / > soak > > Brian I have no doubts about your expertice Brian, I just try to understand what happens If the kiln wash conteins ...

Don't ecpect too much,

a friend of mine fused diiferent thicknesses of float.
It came out of the kiln OK,
but fell in pieces next day.

When float is not float compatible,
which float the float compatible is
compatible with?

-lauri

What Charlie said is a good part of the story. I had never thought the role of hydraulic pressurein such detail. There are counter measures, however. You place the first color frit where you need it. Then you add secind color frit on top. As charlie said more close to the mold surface friction reduc...

Another sculptor interested in relief casting! My pieces have so far been max 50x30 cm, most often smaller. I have made much shallower pieces, trying to keep the thickness 7 to 15 mm. I make ceramic molds, openface, no undercuts, and bisquit fire them before use. They last for several firings. The s...

Hi Charlie,
sorry my floppy English.
I was not going to fasten with screws but with
nuts and bolts. Not tightening too much, and premade holes big enough to allow thermal expansion.

-lauri

Recently we have seen advices of constructing a box around the mold. Ceramics, steel has been suggested, as well as Skamoil boards that you can joint with screws. My kiln has unprotected elements, so I do not feel confident with large steel saggars. I have been thinking about ceramic (bisquit) board...

Rodney, bubbles themself has two properties. If you get enough of them, the mold is porous and can breathe the expanding air from the cavity. This is what Lundstrom recommends. These are good bubbles. Single bubbles in the mold mix, if not breathing, may crack the mold when the gasses expands. Near ...

That is interesting. If you did use it wet, wouldn't you have to grind and resift after each firing to reconstitute the mix? And wouldn't it set up faster after the first time? Ludo (reused already fired plaster) sets plaster faster as I recall. Now I see your point. After being above ca. 700 C both...

Watershed,

can uou use a long handle scoop to add glass
into the flowerpot when needed.
My kiln has a venting hole, and I place
the flowerpot under it, so I can drop more glass
into the pot if I need.

-lauri

Bert wrote earlier: The recipe I was given for kiln casting was 80% sand/20% plaster. Obviously used dry. If the setting time is no problem, you can use it wet. The plaster is calcinated back to dry at ca.240 C. Using wet, you form plaster chrystals within the sand. That makes it bind better. Someon...

Good news, Bert The piece where I tested "slip casting" a layer of AlO+ plaster came out beautifully. The coatong did stick, but was easy to wash off with a soft sponge and water. The piece has a frosty look, with slight satin gloss. I do not know the grit of my AlO. It is really fine, fee...

Hi Bert, in my molds I have used plaster+AlO as a splashlayer. I have used it with float for slumping, but also with soda-lime glass for casting. The glass I cast is pint from a local glass factory. It is veru short glass, much like float. Plaster+ AlO 1to 2 ratio does not stick in flowerpot casting...

A relative of mine works at a cement manufacturer. I asked him what happens to plaster at 700-740 C when it develops cracks. His lab colleagues told that: "(the calcuim sulfate turns to calcium oxide and sulphuric vapors) The cracks usually form at calcination stage 42-240C but come visible at ...

I just purchased a set of diamond pads.
They are 4" with a felt back for a welcro pad
with a angle grinder.
The finest is 8000 grit!
The band is Tellum.

Using a grinder is faster than hand pad,
but hand pad gets to more awkward croocks.

-lauri

Thanks Jerry,

I'm NOT going to spoil old glass,
only trying understand what happens when I
leave an object out of hand.

-lauri

Trying to understand more how glass behaves I have noticed that _very_ old bottles and glasses have a grayish matte surface. I suppose that they were made clear. 1. Is the matte due to devit - that is does glass devit slowly in room temperature? 2. Is the matte due to mechanical wear and tear? It lo...

Sure the flakes were unburnt carbon. The acetone was a liquid, squirted into the mold and lit. OUTDOORS !!! It burns off perfectly clean. I expected it to burn off the wax residues as well but apparently the very high heat only made it to seep deeper. When cooking the glass, that wax gassed out maki...

Jerry Flanary: ... the melting wax is just going to seep into the plaster (my guess). You need the water in the plaster to resist the molten wax (my opinion). That is my experience, too. I tried once to remove the residue vax by burning acetone in the mold. The result was a beautiful cast, filled wi...