I am building a large river (20 foot long) in my layout. the river gorge is 12 inches deep and the river depth will be about 3 or 4 inches. The river bed and sides will be made of plaster molded to look like cliffs/mountains. It will be painted and then sealed with multiple layers of some sealer. does anyone know whats a good sealer to use that will not deteriorate over time and will be completely clear and matte. non shiny. The reason it has to be non shiny is because i have to coat a few inches above the water line and i dont want there to be a noticeable difference between the coated plaster and non coated plaster. Please don't tell me that using water is a bad idea. I heard that before. Plastic water may look like real water but its not moving and thats not fun at all. I want motion in my layout. Humidity and mold growth can easily be handled by removing the water into a storage container when not using the railroad, and using a dehumidifier. Making water look real is also not as hard as one may think. One can create turbulance in water by pumping it through nets . This gives a bubbling effect as in a faucet. And looks great for waterfalls and turbulant water when it goes through rocks and turns in a raging river.