WarmGlass.com

Hi All,

I'm having nagging problems with my molds breaking during steam-out at certain delicate points. For example, I have a wax model that is a candlestick, where there's a cylindrical 1 inch hole in the top to accept the candle. The plaster cylinder that forms the hole keeps breaking and its driving me crazy. I am hand-building using these layers: Layer 1/Face Coat - 40 PP#1/40 Silica/16 Fine Grog/4 Kaolin; Reinforcing with several small fiberglass strips across and into the hole with same formula as Layer 1; Layer 2/Jacket Coat: 40 PP#1/40 Silica/7 Fine Grog/7 Medium Grog/6 Coarse Grog, both layers using a 1 to 2 water to investment ratio. I'm also putting chopped fiber in small quantities in all the water. I'm waiting about 2 hours cure time before steam out, and even if I watch progress real carefully so as not to 'over steam', the 'hole' is breaking off the mold. I would like to hear from others as to recommended elapse time before steam out and if waiting longer (say 24 hours) might 'cure' my problem. In the meantime, that's what I'm trying next.

Thanks!

Cathy

I wrap my molds in plastic bags and then them dry for about 1 week.

Thank you Peter.

I tried waiting 24 hours and still had the issue. For now on this design that has an open clean exit path for wax through sprue [vertical candlestick] I'm just going to melt it out, maybe a quick shot of steam afterwards if I see residue. Trying that now.