RTV questions

[JE]

I have a decent Perch to do, and was hoping to use RTV silicone for a two part cast, the reason being that I do not want to cook the fish during the molding, I want to get as many molds as possible out of one fish, (different positions). I use a sand/clay mix for bedding , will I have any problems with the sand sticking to the silicone ? and if so any ideas on how to prevent this ? ( no High fiber over here)
If I use a thickening agent with the RTV, will I loss any detail in the mould by having to spread the silicone on, I just have visions of air bubbles etc being trapped whilst buttering the thick silicone on.
Any idea how much RTV silicone will be needed for a 15" European perch mold ?
Thanks
John

[Doug Bridges]

You can try to spray the sand/clay with acrylic paint prior to casting (let it dry of course).

Yes, I think you will have opportunity to trap air in the thick rubber. Try a thin coat first and then follow up with a thickened coat, or build a dam around the fish and pour a thick mold on the fish.

[JE]

Thanks Doug, the sand/clay was my biggest concern, I have used the resin/bondo with the sand/clay mix I use with OK results, but the thought of a load of sand in the silicone does not appeal to me, I will test a small area with acrylic paint and see if it works.
I will also do as you suggest and just damn the fish and use a liquid RTV,
Still looking for guesstimates for quantities of RTV for a 15" perch mold ?
Thanks
john

[Doug Bridges]

length*width*depth will give volume
If you use cubic Centimeters then     

1 Cubic Centimeter = 0.000264 Gallons (US)
or 1 Cubic Centimeter = 0.001 Liter (I am sure you knew that)

I give myself a 1.3 multiplier on the volume to make sure I have enough material on hand. But that's just me.