I’m trying my hand at attaching ‘rocks’ that I’ve previously made to the plaster cloth scenery base. I select the rocks I’m going to be working with and place them in some water to soak for a few minutes, meanwhile mixing up a batch of lightweight hydrocal. Knowing this stuff sets up pretty darned fast once it starts I cut the ratios of water and hydrocal in half.
Then the race is on!
I have a spray bottle handy which I use to quickly spray the area for the first rock and start trying to ‘butter’ the rock and get it in place. I’m usually able to get 3 or 4 done before my hydrocal becomes unworkable anymore and I end up wasting about 1/2 of it. The only thing I know to do is keep cutting the mix down in an effort to use it all before it goes rock solid in the mixing bowl. Something tells me this is a good two person job.
I’ve attached my rocks to the scenery cloth using a silicone type of adhesive. I apply the adhesive to the back of the rocks and hold in place for a few seconds and it holds pretty well. If you need to re-position them, the adhesive stays tacky for quite a while. Once it dries they won’t come off, unless you cut away the adhesive. If you find that you have undercuts (exposed areas under the rocks caused by the rocks not making full contact with scenery) you can either mix up a small batch of hydrocal and fill these areas all at once or use a silicone sealant (silcone sealant in place of the silicone adhesive mentioned above) and fill in the gaps and paint/texture.
Nick, I like that “it sets up much slower” part. Man… when hydrocal starts to set up… watch out… that stuff is fast! The package says you have about 8 minutes work time and that’s true, I guess, from the time you start to mix it. But it’s a bit too soupy for a while to apply so you have to wait, at least I do, til it starts to thicken a bit. That doesn’t leave you much time. I might check into this premix stuff.
You don’t want silicone on foam. Be careful of how much you use, it smells bad. Latex caulk works better and smells less. I use hot melt glue when I have a lot of pieces to connect.
A couple. First try adhesives instead of Hydrocal. I’d suggest either Gorilla Glue or Liquid Nails for Projects. Second, if you want to use Hydrocal try using hot/warm water. I found with Sculptamold it dries slower than cold water.
Don’t use hot/warm water with hydrocal; it speeds up the setting/curing process.
Instead of waiting for the hydrocal to thicken; mix it up thick, not thin or soupy. You can add hydrocal to water and actually make a paste; just add hydrocal until it absorbs all of the water and you end up with a paste, not soup.
i use regular old joint compound to fasten the hydrocal rock moldings…perfect working time…i do spritz the back of the casting with some water before i “butter” it with the plaster…you always get some that squeezes out of the edges…for that i use some aluminum foil and dab the excess that oozes out…makes for a perfect looking rock!!..just my thoughts…
Also if you are applying a casting over a surface that is already dried plaster or hydrocal, wet the area first before slapping the casting in place. The dried plaster of the base will quickly suck up any water in the casting and dry it out too fast, often leading to a crumbly or powdery casting.
I’d go with my favorite adhesive - latex caulk. ANy gaps between the casting and base - fill in with drywall mud or scultamold.