For my deep rock cut I used crumpled and flattened tin foil as the mold for Sculptamold. As it started to dry I put it against the foam base and it has done well. Sorry, I don't have a photo account.
Good luck,
Richard
Bragdon Enterprises how-to page on using their flexible molds;
http://www.bragdonent.com/articles.htm
For simple curves, you can curve Hydrocal castings while they are almost set up but not quite hard. This was made with a cut stone mold. I cut a simple form from pink foam and curved the mold over it about 10 minutes after I poured the Hydrocal, while it was still slightly soft but no longer runny. This is a concave casting. For convex castings, simply put a piece of Saran Wrap over the Hydrocal side before you bend it.
It takes an iron man to play with a toy iron horse.
I'm 98% certain that I used Cripplebush on this curve. I would definitely recommend the products. In this photo, the outcropping on the lower right end is hydrocal rock casting, and the curve continuing to the tunnel (and above same) is the Cripplebush rubber rock.
The rubber rock was nice for the curve as I did not want the depth of casting there, and the relatively thin rubber rock was easy to just hot glue to the upper plywood curve edge and to the base plywood below.
I found it nice to use the Hydrocal castings in some places and the rubber rock in others, to have more options. I painted both a shade of slate gray, then colored with about 6-8 acrylics colors (all the way to white highlights). Maybe a black wash in there somewhere. When painted similarly, the castings and rubber rock blend superbly.
20200424_084006 by Paul Ahrens, on Flickr
Paul
Modeling HO with a transition era UP bent
You might look at Brandon Foam rock castings. I've done a few of these. They use a chemical resin for castings. Their molds are superior to most of the plaster molds I've used, but you can use those, too.
The castings are very lightweight. They are stiff when the resin hardens, but just reheating the castings with a hair dryer will temporarily restore flexibility.
I have a couple of their larger molds. You can cut the finished casting with a knife or strong scissors.
www.bragdonent.com
The level if detail of these rock faces is much better than a standard Hydrocal casting. Yes, there is a bit of a learning curve, both for the casting and for the painting process, which is a multi-colored series of washes to achieve the best effect.
This is some castings just out of the mold. They are white in color. These are quite large. I cut the larger ones in half horizontally for long, thin strips to put behind the one visible track. There are 4 staging tracks behind the castings.
This is a couple of the cut pieces, joined with some plaster.
Here is the whole rock face, loosely assembled. This has the first coat of coloring on it, brushed with black, dry Tempera paint and then lightly swabbed with a sponge. The black gets into the crevices and deepens them to the eye.
Ths is an earlier picture with the painting finished.
Not the least of the virtues of the Cripplebush flexible (foam rubber like a pillow innards I assume) rock facings is for protection where the track curves near a benchwork edge but for whatever reason a backdrop is not practical or wanted. There are various ideas out there to prevent derailed or speedy trains from flying off the edge of the earth -- trees made with stout nails as tree trunks being one popular option -- but the flexible rock facings have the added virtue of not damaging the cars or locomotives that attempt to take wing.
Dave Nelson
It has been quite a few years now but I bought several cripplebush rubber rocks and I'm quite satisfied with them. I have one of their river beds, too. Good stuff.
IMG_2475 by Edmund, on Flickr
Cheers, Ed
I have not been happy with the Chooch flexible products.
I bought a bunch of flexible rocks castings at Legacy Station near Atlanta, Georgia that are fantastic. Each one is about 10 inches by 14 inches and about 1 inch thick.
Unfortunately I have no idea who made them.
-Kevin
Living the dream.
http://cripplebush.net/
Good luck. They sent my order within a couple of weeks.
I am getting ready to model cuts on my HO layout. A few years back, I was introduced to flexible rock facings or bluffs. These were great as they curved easily. Now, that its time to purchase these they seem very scarce. Does anybody have a good source? Chooch makes flexible stacked rock walls but no natural outcroppings. Any advice greatly appreciated.
Jim Norton
Huntsville, AL