Casting Call

Collection of latex rock molds so far

I've been busy making rock molds.

Flat ones and 3D ones. 

Several types for several scenes. 

Flat ones for sheer cliff faces. 

Chunky ones for ledges and outcroppings. 

And extras in case I bungle the casting process.

Two modules for a shelf layout. Parent's backyard in Scarborough. 1977. Polacolor.

In the summer of 1977 I spent some time learning how to make rock molds from latex and casting rock scenery in plaster. 

Both modules didn't survive a 1978 move across Scarborough

The method I used was taken from Bob Hayden and Dave Frary's two-part article, Casting rocks from plaster, that appeared in the Dec '74 and Jan '75 issues of Railroad Model Craftsman. The first part deals with making latex models from rocks, and the second is about using the molds to cast plaster rock formations and arranging them on your layout.

The Jan '75 issue also had the first instalment of John Olson's Stop Gap Falls series. It made quite an impression on me and resurfaced in my mind when I started to work on my two modules in 1977. They don't have the drama of Olson's, but they were to be representative of somewhere in northern Ontario, not the Colorado Rockies. 

A couple of garden border rocks were pressed into service for some molds

Back in the 70s I followed Hayden and Frary's advice on where to make molds:

"This [JDL: making a latex mold of a rock] can be done either on location in the great out-of-doors, or on your work bench using a chunk of rock hauled in from the boonies. All things considered, bringing a five or six pound rock indoors is the better option ..."

This time around though I figured I'd follow John Olson's:

"I've made many [JDL: rock molds that is] in the field, working on rock faces that were far too large to attempt to take home. Rock mold expeditions make fun family outings. Besides, you'll ensure that your molds are like no one else's - unless they happen to discover the exact same rock you did, and that's highly unlikely!"

Making sheer face molds from a retaining wall. Pre-gauze state.

The latex came in a small jar from the local art supply. The procedure is pretty standard: brush on 4 or 5 coats (let completely dry between applications) on a clean rock surface, then apply a layer of medical gauze with latex brushed over it, and when dry apply 3 to 5 more coats of latex depending on the thickness that has built up. After everything is dry, carefully peel the molds from the rock. Go slow and easy and they won't tear. On a nice, sunny summer day the whole job to make 6 molds takes from just after breakfast to just before dinner. There are many places on the internet that explain all the details for making rock molds, but this is the gist of it.

After application of the gauze and latex layer.

Strictly speaking, authenticity-wise, I should have flown to California, hiked up the San Gabriel Mountains, and made some molds near the Mt. Lowe Railway roadbed. Even though I'd love to do that, it wasn't an option, so I looked around for some suitable stand-ins here in Ontario.

One problem with making molds in the field is that if you run out of latex you're done. I found some rather interesting 3D rock shapes while working on those sheer face molds, but I didn't have enough latex on hand to make more molds than those already in process. That'll be for another outing.

Somewhere along the Mt. Lowe trail in May 2015