Hi. It’s been a long time since I have used Hydrocal in doing scenery work. First of ALL what is the mixture of plaster to water? Next can you just brush it onto the plywood base directly , then add your foliage to it? I am talking about for level landscaping not on hills or mountains.
Also can Hydrocal be mixed with powdered paint to give it color?
Thanks I would hear some opinions please
If I may, I’d suggest you not simply plop it onto plywood–instead, get hold of some Sculptamold, and put that onto your plywood.
It has a texture so you can build it up slightly here and there so your layout won’t look like it was built on a golf course. Cheap and easy to use, less messy than plaster, too. You apply it with a putty knife or spatula and then you have plenty of time to smooth it or push it around as you like.
Mix it with either powdered paint or liquid paint (like the 55-cent stuff from Wal-Mart) if you like.
I like Gypsolite for the same purpose. It has a gritty texture that looks like natural ground. I mix mine with a few squirts of cheap dark brown acrylic paint. That way it comes out a light tan and looks like dirt.
Best way to mix hydro cal is to have a container with about 1 cup water. Personally I don’t liketo mix morre than that because of the short setting time. Use cold water. Add hydrocal to gradually till the water is full of hydrocal that is wet. Then use your fingers to mix it so that you can feel if you have a good mix with no lumps. Yes you may wear a rubber glove. Its reccomended in fact. Apply yhe hydrocal to your towels or brown paper and drape them ver your base structure. I’d also recommend covering anything underneath your working area so’s not to mess it up. Keep a 5 gallon bucket handy with a couple gallons of water in it for washing out your mixing bowl between mixes. Don’t dump it in the sink, it will set up in the trap and plug it solid.
You can make a more controllable mix by adding more powder but do it in small amounts because of the set time.
I don’t have experience with adding powdered paint to the mix, I’m afraid it will mess up the set time or not set at all. Hydrocal takes latex paint very well and you can add your texturing materials to the wet paint.
There are guys on the forum who do have more experience with additives though. You might find their answers by using the search feature under plaster, or hydrocal, or even sculptamold.
What are the best way to apply Hydrocal to a vertical extruded polystyrene surface?
Shop Towels dipped in hydrocal.
Nylon Screen.
Aluminum Screen.
Sculptamold.
Or something else?
Andrew Falconer
At the risk of sounding facetious, the answer could be “yes”… I’ve tried each of these, actually, but with either Plaster of Paris or Durabond, which is an acrylic/plaster mix used for patching walls. I would think Hydrocal would work as well.
I like Durabond as a first coat with paper towel because it sets up very hard, has a long working time, and makes a solid base over screen or extruded foam. You do have to cover the floor if you are putting it over screen because some of the material will drip through. I then cover the Durabond with plaster of paris or Scuptamold. Having tried Sculptamold for the first time on my last scenery project I’ve become a believer.
Sculptamold also seems to adhere well when applied directly to the foam, but I have never stressed it - my layout doesn’t have big temperature or moisture swings.
So any one of these ideas will work in my experience - you have to experiment. Your mileage may vary…
George V.
I will try them carefully. It will be great if the hydrocal will stays on the vertical foam surface.
Andrew
The method of coloring the Hydrocal hasen’t really been addressed yet.
I have found that using powered masonry dyes has produced the best results for me. Paint and some of the liquid tints seem to only give a tint to the dried, cured plaster and some will affect the overall properties of the plaster in it’s drying and durability of the cured product. The dye added to the dry plaster will result in the approximate final dried color of the cured plaster. Just think of ceramic tile grouts, these are colored much in the same fashion. Of course the dry plaster is always added to the water then mixed.
Most of the time I’ll use the masonry dyes to color the Hydrocal for casings or for roads and parking lots. Large scenery spots are usually done by Either Hydrocal soaked towels over wire screening or ground goop over hot glued toweling on cardboard lattice. If I ever do need to use a dyed Hydrcal over ply it is troweled on over stapled wire screen. Scultamold is a great product, but for large areas I as well as others find that other concoctions will work as well and at a much more reasonable cost factor.
Coloring of the scenery base (plaster etc) is not always nec. as I find that an initial coat of earth colored acrylic paint works great and also acts to bond the first coatings of any scenery materials; ground foams and/or ballast, sand or gravels, etc.
Various ground goop recipies of structolite and combinations of plasters w/ other additives or Durabond do seem to work better over any bare level plywood instead of the straight Plaster of Paris or Hydrocal. This is more of a trial and error and what works best for you.
Andrew,
I may have mis-stated something - I don’t think Hydrocal by itself will stick to a vertical foam surface - it would slide down. If it’s got some “backbone” from paper towels that is a different story. Even then, the towels may want to slide down a perfectly vertical surface, now that I think about it. It would need some thing to hold the towel - maybe some temporary pins.
In fact, I don’t think it would stick to a flat foam surface because it would pop loose when set, unless there is something under it. Sculptamold seems to stick a bit more and has some give.
When I did an absolutely vertical surface I had screen underlay. If the foam has some shape so it’s not fully vertical then maybe you could skip the screen.
Sorry for the confusion.
George V.
Hydrocal will stick on any vertical as long as the consistency of the mix is not that loose.
Hydrocal was used extensivly for ceiling cornice and decorative castings for many years. The dried castings were bonded with additional buttered batch for securing. Some wire and reinforcement was sometimes used.
I had placed hydrocal castings on pink foam some years back. When they were removed to alter the section, it took a chisel to pop the hydrocal glued castings off the foam. Much of this was near vertical.