Hi All, I have been thinking about making my own rock molds. I have some very nice limestone rock formations here where I live. The only thing is I just don’t know what to use to make them. Can someone point me in the right direction.
Thanks
The easiest thing to do is use a latex rubber product that you just paint on to make a mold. I’ve used a product sold by MicroMark but there are probably others that are equal. You paint on a couple of coats of the rubber and then add some gauze in the next layer to strengthen the mold and then add a couple more layers to build up your final mold. Make sure to let each layer dry before adding a fresh one. Also, try the search the community function of this forum. I believe this has been discussed before and probably has some good info for you.
Joe
Latex rubber has been the old stand-by and takes many coats and many days. Smooth-On has a line of various rubbers and RTV’s that could work.
I have used WS Latex Rubber. Brush on the first two coats, allowing to dry between layers. I add some cheese cloth either to the 2nd or 3rd layer for added strength. Then add a couple more layers. I ususlly do 5, though it may be a little overkill, my molds are very strong.
For some rock faces I have used crumpled tin foil. I usually keep some tin foil handy in case I have leftover plaster from making larger molds, I can make some small ones easily.
If you have some hunks of plaster or you can make a couple of thin pours on tin foil, crush it into small chunks and color the color of your rock faces and use it for talus, the loose material at the base of a rock face.
Good luck,
Richard
This is exactly what I’ve done. I save leftover plaster in a plastic cup. When I’m ready to make rocks, I cut away the plastic cup with a razor knife and hit the chunk of plaster with a hammer into smaller pieces.
Making small rocks out of a big rock.
Rocks to be added to layout.
After coloring, I drybrush the highlights using antique white.
Chopps -
The simplest and fastest way to make a small rock mold is with Play-Doh. Take a rock, press it into a ball of the dough, remove the rock, and pour the plaster into the cavity. When the plaster sets, peel off the Play-Doh. You’ll destroy the mold, but you can roll it into a ball and make another. Plus, you can vary the angles you use to press the rock into the dough, so no two plaster “rocks” will be alike. If any Play-Doh sticks to the plaster, you can remove it with a toothbrush and some water.
Thanks for reading MR,
Terry
CHOPP’s:
All are great suggestions, one thing I like to do is hand carve rock formations with a semi slow drying plaster. Mix in small batches, apply to the surface then as it begins to dry I use small spatulas, carving tools like dental tools, wire brushes along the surface for striations, a small knife to carve; whatever works to make personalized rocks that you may not find, like what we have in Tennessee along I-40, layered shale and sandstone.
As suggested, Play Doe works great, as well as good clay. Just push the rock in there and gently remove it and pour in the casting plaster. Also, WS and other companies make all kinds of rock molds. It is a fun part of the hobby. After staining, painting and placement of the rock you’ve made, it can really look good. Study pictures and think like a rock.
Robert Sylvester, WTRR
The brush on latex adding gauze reinforcement does work rather well. The mold is quite flimsey and will need to be supported to a somewhat level form to pour the plaster. I find that rolled dampend paper towel suitable to use for this.
RTV is the best product to use but is expensive and large/ deep castings will require a substantial amout of this “precious” stuff. A good method of fabricating a mold using RTV is to start w/ a flat glossy surface, glass, ceramic tile etc. You place the rock to mold on the surface and need to place a perimeter “dam” surrounding it. The dams should be fitted close to no less than about 1/2" and they need to extend about min of 1/4" above the rock. These dams can be held w/ hot glue. Hold well and removes easily once RTV sets. Mix the parts and pour. Do have other smaller molds set up w/ other formations as any extra RTV can be used for them. This way you will not waste the product. Once RTV 2 parts are mixed it has to be used or it is junk. Advantage of RTV is that it will make hundreds of castings and not rip, tear, or otherwise degrade from multiple use as w/ the latex.
One additional application of the brush on latex method is making molds from small sections of rock formations in the field. If you find a formation that is perfect for what you want you can take your stuff out in the filed (on a good day) and make your molds.
Joe
Thanks everyone lots of good advice. Joe that’s what I plan to is go looking around in the hills. I went to a craft store the other day and picked up latex, boy it stinks.There are a few rocks here by the house that I’ll first then go out to the hills.