I’m putting in a bridge scene on my layout, and I’m planning to use Peco plaster bandage over a wire frame, to bring the landform down to the river level. I’m thinking of pouring a thin layer of plaster over the plywood creek base, to ‘blend’ the riverbed with the landform.
I’m going to be using tinted Envirotex to represent the water, and I was just wondering what would be the best way to seal off the (rather porus) plaster? I’m considering painting the plaster, then applying a layer of PVA glue before pouring the envirotex.
Sealing isn’t necessary before applying epoxy resin like Envirotex over plaster. Ensure you have plaster and/or other materials filling the entire water course and there’s no way for liquid to seep out. I’ve built many a creek bed and used epoxy resin for water. I’ve never done sealing beyond normal scenery finishing, and the epoxy doesn’t cause trouble.
I’m not sure about the Peco brand, but most plaster cloth/bandage has holes in it. Be sure to add a good layer of plaster or some such so that all the holes are sealed where you plan to put your water. Most folks seem to add some plaster whether doing water or not to seal the holes before adding more scenic material, as some of the holes can be quite noticeable.
I haven’t used plaster cloth, but did use plaster to seal my pond and Envirotex for the water. I like the looks of it.
One thing I suggest, is that after pouring each layer of Envirotex, make a tent out of newspaper or some such to keep dust and other unwanted products from settling onto it before it hardens. Do this after each pour, which should not be more than 1/8" thick. Three or four pours should be all you need.
A couple of notes about Envirotex and plaster. Your first pour will be partly absorbed by the plaster and drawn up into the edges. After that, it’s pretty much sealed up and subsequent pours will not seep in.
I’ve just had my first less-than-perfect Envirotex experience. I did not mix it thoroughly enough before pouring, and as a result the surface never hardened properly, and remained sticky for several weeks. My solution was to add another layer, very thin, and make sure to mix it thoroughly this time. It worked fine.
Be absolutely sure that you have plugged every hole below the water line before you pour. If you leave even a pinhole, your water product will find it and an amazing amount of product will be lost (and gained somewhere unintended).
I normally brush on to plaster a coat of my ballast glue mix and let it dry before painting. This seals the plaster and the paint colors stay true for years, as they stay on top of the plaster. Doing this step also keeps the plaster just a bit more resilient, and not quite as sensitive to crumbling or other brittle behaviors. Once painted and dry, your Envirotex should bond nicely to and be very protective fore your paint.
After the scenery contours have been covered w/ plastercloth, you should be sceniking the banks and bottom of the water feature anyway. An additional coat of plaster and bottom/ bank painting will seal the area for the Enviotex. I believe last month (May/ June) MR had a good article on this. The Enviortex will “creep” up slightly as mentioned, addional touch up painting, flat finish and/ or senery material will hide this. Some of the most problematic is when you have piers, and other partially submerged objects as the creep is quite noticeable and a touch up w/ flat finish is needed.