I am doing my foam mountains and need to know how thick the typical rocks you cast with Woodlands scenic are as I need to leave room for them. 1/2", 1" ?? I have some vertical rock walls and thing are tight.
They vary and your parameters are about right. You can always dig into the foam a little if you get a big one.
BUT, Why not carve the rock face directly in the foam? Its not all that hard and I think it looks good. Everyone has WS rock castings. You can paint the foam directly with acrylic washes and have an incredible detail if you do not put on a plaster or latex topcoat.
Art asks a very good question. If you take the time to carve rock fissures and facets directly onto the foam, you can paint it up nicely and have a very convincing rock face. However, to get to your question, count on about 3/4", perhaps all the way to an inch for the maximum depth for most commercial molds. Since you already realize that you are tight, keep that NMRA gauge handy to check for standard clearances. Be prepared to leave even more room on curves. Steamer cabs, at the rear roof corners, are the big problems in my experience. Can’t say for diesels.
I’ve got 3 WS molds. 1 large rock face and 2 small outcroppings.The large face is about 1.25" thick and the 2 smaller ones are about 1/2"-5/8" thick. You don’t have to fill the molds up all the way, so you can make them thinner if you want.
You are absolutely right, loathar. The only concern I would have is that if you err a bit on the low side, there will be some very thin spots where the mold’s inner surface rises up to just below the surface of the poured plaster/hydrocal, and that would be a source of potential weakness and fractures…if that is a consideration. Best, in my view, to fill the molds with plaster to within a couple of mm of the lips, assuming you can keep them level when filling them.
Selector-That’s where that rare thing called “common sence” comes into play. God forbid you end up with different size and shaped rocks.[:O][:P]
After all, it’s not like it’s ROCK-ET science.[:D]
As thick or thin as you want. I make some casting 1/4" thick and other’s 2" thick, it all depends on the look I’m after.
You can change the look of the WS castings, by only filling part of the mold, and varying the thickness of the castings. Yes, thin castings are more susceptible to breakage. However, that can be a GOOD thing. I often intentionally break the castings to alter their appearance, or to fit them into odd spaces.
Nick
[#ditto]
Well thanks. I am just using the foam to form the general shape of my mountains. I’ll be putting down plaster cloth and so forth for the detail. I love those hydrocal rocks! If I carve any rocks, I’ll carve them out of hydrocal, not foam. Anyway, I’ve got the idea now. Good to know you can vary the width. my tight spot I have about a 1/2". Guess I’ll make it work somehow…
Another option is Bragdon foam for rocks. This is a chemical product rather than a casting plaster. When it comes out of the mold, it is still soft and pliable, and even after it hardens up it can be softened with a hair dryer. I’ve got a package which I still haven’t used, because I haven’t gotten to that part of my scenery yet.
gear-jammer has done a lot of this, and her results are excellent.
www.bragdonent.com if you’re interested.
On our large club layout depicting the Pacific Northwest we used a huge amount of Hydrocal rock castings mostly based on the WS molds. Initially we filled the molds completely, producing some castings of 1 inch thickness. This worked fine and produced a hefty rock. However, to save plaster and fit into areas with tight clearances we found we could produce a good, quicker drying, but somewhat fragile casting of 1/4 inch thickness. These too worked well, but were subject to some cracking. We used the cracked pieces to make a somewhat different looking rock from the same WS mold. www.BSME.org
For thinner molds I sometimes use Durham’s Water Putty… a bit stronger (and heavier) so lets me have nice thin molds in tight spots… Just my 2 cents.
Brian