Tips for Best Results

First: Pur Black Foam or Dow Enerfoam foam sealant works well for large/deep crevices. The tighter the seams are on your rock, the less of the foam product you’ll need. Your chosen seaming compound can be worked into the seams after the foam is set. If you end up with too much foam in the seam, it is easily carved away. Great Stuff is now available in a black formulation – this isn’t as dense as the Pur Black or Dow Enerfoam but it will still work if that’s all you can find. We like the Pur Black because it dries a dark gray instead of yellow – less work to cover that up with the seaming material.

We use several types of seaming material depending on what type of base we’re making. Here are a couple options:

Fix-It-All and cold water (our preferred product): We’ll add a little mortar dye to make it gray. Mix just enough to make a ball that you can hold in your hand and work into the seams. The cold water delays the dry time. You can add cellulose house insulation for texture or add texture with a dry paint brush or household sponge.

Sheet Rock Joint Compound (45 or 90 minute set is recommended) and cellulose house insulation: Mix to a workable texture, use a paintbrush or dry sponge for texture.

Hydraulic Cement: We use Thoro brand. We’ll use this when we need a very hard seam on a piece that may be in a high traffic area and could be chipped.

Krylon Fusion spray paint in River Rock color OR satin poly acrylic mixed 50/50 with water. You can also use a flat gray primer to seal your seams. Flat gray primer is probably the easiest to source.

One coat of your choice of sealant on your seam is fine but be sure to hit them heavily to prevent the paint from seeping into the seams and making them darker than they should be when you paint.
Latex Paint – Spray/Brush Technique – We use this technique exclusively in our shop.

There are other ways to paint our rock but this technique, if followed as described below, is foolproof.

Use a flat latex interior house paint, we buy the cheapest stuff we can find.

Here’s the recipe: Mix 1 part paint, 1.5 parts water, 1.5 parts rubbing alcohol.

Spray your chosen colors on with any type of atomizing bottle, we re-use the alcohol bottles or use pop bottles. We recommend chemical resistant spray heads for keeping your spray bottles in optimal working condition. Work your paints into the rock with a brush. Colors will run and drip together, that’s okay. You can catch large drips with your paint brush.

*Have several colors on hand for best effect – black, browns, grays, golds, greens, reds, purples, oranges.

*Continue spraying color and dry brushing until you get the look you want. Let dry.

We use this paint recipe and technique because it is a foolproof method!

Other Paint Method Options:

Tempera/Acrylic Paint – Brush Technique:
First Coat – Use a wash of tempera paint mixed 50/50 paint and water, use black or brown first for good depth/definition – don’t worry if the paint beads up during this first step. After the first coat, use a dry brush to add layers of acrylic color to your rock until you achieve the desired effect. This technique is a bit more time consuming than the latex house paints and less predictable.
Final Finish – seal with Poly Acrylic (satin) mixed 50/50 with water OR Krylon Matte Finish (Matte!! Any other finish will be too shiny)

Regarding which product you use for a finish – if you’re just sealing a small rock, using the Krylon matte may be the way you want to go for. For larger projects, we’d recommend using the Poly-Acrylic and water – it’s less expensive with less fumes.

Call us with any questions – 406-543-5501 – We’re here to help.