WarmGlass.com

Just moved to casting from slumping and have been given a big bag of a this mold making material but can't find any information about it. It is a French product which may be known under a different name in UK or USA. Does anybody know anything about it??

Best wishes

Linda Denli wrote:Just moved to casting from slumping and have been given a big bag of a this mold making material but can't find any information about it. It is a French product which may be known under a different name in UK or USA. Does anybody know anything about it??

Best wishes

Is this it: http://www.ucpi.fr/precision.html

If not, try looking under U S Gypsum. Brock

If I'm correct, it's to make a reusable mold that you can then use to make many plaster molds. It's not something that you'd want to use in the kiln!

Page 3 of the following link from bullseye's "Get Smart" series talks about hydrogel, which I'm guessing to be similar to your hydracast.
http://www.bullseyeconnection.com/pdfs/ ... eet_05.pdf

Of course, I could be wrong, but just a guess...

I looked in one of my kilncasting books, but could not find exactly that product name. I suspect it's similar to hydrocal which is what I have used in the past, in a mixture with silica flour. The silica allows me to break apart my mold easily.

Why don't you make a small pendent/object from clay and cast it in your product? See if your glass will stick or come out easy. I think most hydro... products are like plaster/cement and will stay very hard. Probably good for open face molds that will be used several times.The mold formulas I've read always include additives to help release the glass from the mold.

Oh, by the way, I was taught a really easy way to mix my dry casting material with my water. Fill your mixing container with water. (Allow a little room to add your dry ingredients.) Then sprinkle your dry casting material into the middle of the bowl. The powder will sink. Keep adding until the dry powder doesn't completely sink and starts forming a small 'volcanic' island. Now you have the proper ratio of water to casting mix. Mix it, pour it into your molds and tap the air bubbles out from the slush, add fiber to reinforce and cure and dry. Voila! (or did you already know that one?)

I'm by no means an expert but I like to experiement in my kiln.
Good luck with your product.

Glassylass wrote:
"

Oh, by the way, I was taught a really easy way to mix my dry casting material with my water. Fill your mixing container with water.
(Allow a little room to add your dry ingredients.) Then sprinkle your dry casting material into the middle of the bowl. The powder
will sink. Keep adding until the dry powder doesn't completely sink and starts forming a small 'volcanic' island. Now you have the
proper ratio of water to casting mix. Mix it, pour it into your molds and tap the air bubbles out from the slush, add fiber to reinforce
and cure and dry. Voila! (or did you already know that one?) "

That is the traditional way sculptors mix pure plaster.
For that it is OK.
For plaster/silica sand it works too,because silica sand does not absorb water.
Other possible additives like kaolin, molochite, luto
are good because they are porous, but they also
absorb water. Then you have to estimate the extra water
for the refractory
OR
mix them separately each with its own water
and mix the slurs at the final mix stage.

-lauri

Many thanks to everyone for your advice on this.

Brock was right about the site - although they didn't give much 'how to' information - I went ahead anyway and cast a smallish open mold which I sprayed with kiln wash and then filled will smashed up spectrum 96 melted from a suspended flower-pot.

It was an acceptable first attempt and the mold came away from the piece beautifully.

I like the Hydracast and it is easy to use (although I think more expensive than mixing your own formula) and next time will try the 'traditional' way of mixing.

Best wishes

Linda