Posted: Fri Apr 02, 2004 6:54 pm
[/quote] "Jerry"
According to Thwaites the ludo may cut down on cracking because a) the ludo has various sized particles and helps with packing and b) chunks of ludo act as aggregate to stop cracks running through the mold. Also ludo is classified as a refractory or a modifier rather than a plaster (or binder) because the gypsum has already "gone off" and has no binder abilities (though it does speed up set time.)
Who is Thwaites?Thanks
Katia[/quote]
"Delores"
Angela Thwaites wrote mixing with the best based on her research with Keith Seybert.
Jerry, Once the plaster/silica is fired above 1500 doesn't it become cristobilite? I think they (Thwaites/Seybert) considered the fiberglass and vermiculate (perlite as a modifer which adds in the elimination of physically and chemically bound water to escape out of the mold while adding strengthing to the mold. But Bert is right when you get into the higher weight pieces and longer holds his perlite (vermiculite is virtually the same principle) is definately a stronger mix then with just fiberglass. I felt the perlite and vermiculite is so easy to get it wasn't worth putting my health at risk with the ludo but I think it was in the early 90's that Lucartha Kohler was using ludo and obviously she gets stunning results along with her zircar molds so it obviously works well.
Kathia....Have fun experimenting there lots of cool ways to get to the end of the road and in the end it's the type of work that you're doing that will help you be guided by the best way for you. Fortunately there is many possabilities to try until you get what works best for the art you're trying to create. If your casting at high temperature for extended holds a pate de verre mix probably isn't your best bet, I try a stronger mix. Good luck and I hope your project turns out great.
According to Thwaites the ludo may cut down on cracking because a) the ludo has various sized particles and helps with packing and b) chunks of ludo act as aggregate to stop cracks running through the mold. Also ludo is classified as a refractory or a modifier rather than a plaster (or binder) because the gypsum has already "gone off" and has no binder abilities (though it does speed up set time.)
Who is Thwaites?Thanks
Katia[/quote]
"Delores"
Angela Thwaites wrote mixing with the best based on her research with Keith Seybert.
Jerry, Once the plaster/silica is fired above 1500 doesn't it become cristobilite? I think they (Thwaites/Seybert) considered the fiberglass and vermiculate (perlite as a modifer which adds in the elimination of physically and chemically bound water to escape out of the mold while adding strengthing to the mold. But Bert is right when you get into the higher weight pieces and longer holds his perlite (vermiculite is virtually the same principle) is definately a stronger mix then with just fiberglass. I felt the perlite and vermiculite is so easy to get it wasn't worth putting my health at risk with the ludo but I think it was in the early 90's that Lucartha Kohler was using ludo and obviously she gets stunning results along with her zircar molds so it obviously works well.
Kathia....Have fun experimenting there lots of cool ways to get to the end of the road and in the end it's the type of work that you're doing that will help you be guided by the best way for you. Fortunately there is many possabilities to try until you get what works best for the art you're trying to create. If your casting at high temperature for extended holds a pate de verre mix probably isn't your best bet, I try a stronger mix. Good luck and I hope your project turns out great.
