I'm currently working on a swamp dio with part of a stream running through. I was thinking of using a caulking agent from Selleys which is transparent for the stream. I guess it's a bit like mastic though I've never used mastic myself. Its a copolymer based. Problem over here is I can't seem to get my hands on any Woodland Scenic products and ordering some via the net is really too expensive given the exchange rate.

The trouble with the stuff is it is really thick and doesn't really flatten out without some manual help and if you agitate the stuff too much it kinds of goes murky and bubbles which would be great for a waterfall or a rapid except I need a stream.

Any help from you guys would be very much appreciated as to how to make the stuff less viscous and flow better as I need it to form around the roots of the mangrove trees I made and the grasses supposedly half submerged in the water. I've already tried diluting it with thinners but it doesn't help as it doesn't absorb the thinner.

Thanks.

Maybe a few layers of gloss varnish, tinted with browns and greens, painted in and around the Swampy area, and in your stream would work. Start with a black base. As all the grasses, etc will reflect on the glossy surface, it should look well. The more layers the better
The water in the picture below is made the same way. No more than 2 or 3 mm in depth in reality. The waves were made from clear superglue gel and just painted over with the same tinted varnish. I think it has 10 layers in total ... 1 layer each day!
Dont know about the stuff you are talking about .... never tried anything like it!