Does anyone know if i can use sculptamold for a base in a river and when dry pour envirotex epoxy on top?
I've poured Envirotex on a lot of surfaces and never had a problem with it. Scuptamold is just paper mache, so as long as it's fully dried, no problemo...
However, you should probably either paint your riverbed using latex colors which will seal any micro-leaks you may have (Envirotex loves to dribble out of the smallest holes it can find), or texture it with dirt, stones and other river-bed stuff before pouring the resin.
Make sure you follow the recommended thickness that Envirotex tells you to pour, as making your pour thicker may greatly increase curing time.
You can also tint Envirotex resin with enamel paints if you want your water to not be so crystal clear, or give the bottom layer a greenish tint, the next layer less green, and the top no tint. This will add a lot of depth. You can also dribble enamel paint into your river/stream to infer industrial waste, mixing it around with sticks or straws to thin it out.
Be prepared to blow on your Envirotex using a straw to get rid of bubbles. The CO2 in your breath takes the bubbles away when the resin is still "wet". You can also use a propane torch for this, but be careful, especially with parts of your scenery that can be damaged by excessive heat that adjoin the river.
Envirotex cures to a near-perfect glassy surface, but it creeps up on to rocks, logs, river banks and also makes any dirt on the river bank look darker. I don't finish my river banks until the resin is cured, then I paint the river bank with latex paints...then apply a texturing gel to make waves, rapids and give the "water" surface a more realistic look than mirror flat. After the texturing gel is dry and clear, I'll add river bank materials (sand, dirt, rocks, logs) so most of the resin "creep" is hidden. Any rocks that are sticking out of the stream that have that resin creep glossy look, I paint with appropriate flat colors, getting rid of the glossy resin creep.
Photo (1) - this is a river I made for a customer on his Ntrak 2000 modules a decade ago or so using the above described Envirotex techniques. Rock carvings were done by my late buddy Kelly Newton:Cheerio!
Bob Gilmore