Concrete Cabochons Part Two: Finishing Techniques

Our little concrete pancakes have hardened and we've carefully peeled them off the tray. Don't despair if they more closely resemble the ugly duckling than the swan at this point. We're still just getting started. Despite our best care, concrete will still seep under your inclusions where you least want it. But judicious use of sand paper can recover our designs as well as revealing the beautiful aggregate patterns in the concrete. And additional layers of color will help soften, brighten, highlight and/or improve your design.

Cleaning Up the Designs

The first step in cleaning up your designs will be to remove any excess concrete, whether it's obscuring your inclusions or has crept past your intended borders. You may use sandpaper, Dremel tools and bits, sanding blocks or even dental picks; each has it's own place.

Here's a rough guide of what to use when:

Coarse Sandpaper when you need to remove a lot of material

Entire design is obscured

Reshaping borders

Removing large lumps and bumps

Sand back to expose aggregate

Fine Sandpaper when more care or less removal is needed

Smooth rough edges

Remove Scratches left by coarse sandpaper

When coarse sandpaper might damage the design

Wet/Dry Sandpaper

Polish concrete

Remove scratches from concrete, glass, steel, etc.

Picks & Awls

Remove plant material or polymer clay from hardened concrete/designs

Scrape away concrete from specific design lines

Draw designs. This works particularly well in concrete that has hardened, but not fully cured.

Dremel Tool

Based upon the attachement, you can use your Dremel tool to do all of the above

Wear safety glasses as the Dremel kicks material up and back towards the face.

Water

Rinse cabachons to remove dust and preview what an epoxy finish might look like.

Straight off, this piece didn't look much like a keeper. I reshaped the edges with sand paper and cleaned up the concrete around the washers with a dental pick and a couple swipes of wet/dry sandpaper. Adding color will almost certainly be next.

Adding Color

I use a wide range of paint media to enhance my pieces because each has its own special characteristics. Start with what you have and know best, then experiment from there.

Acrylics: Produce a solid color base with very little work, and can be rubbed back with a damp cloth to expose concrete. Acts somewhat as a resist with most other media, so it's best to use it last unless you want it to resist other media. I usually apply it with a rag or my finger (sometimes I even remember to wear gloves).

Rub n' Buff: Best used in sparingly; a little goes a long way. I love these metallic wax finishes when I want an antique, rustic or archeological effect. The copper and antique gold work especially well with burnt umber acrylic paint

Pitt artist pens: These are lightfast, waterproof inks that produce a transparent effect. You can use them to draw directly onto the concrete, to color stamps before stamping, or to layer on top of acrylics. When layering on top of acrylics they can be rubbed back to produce a fine

Stamping: Stamp images directly onto the cured concrete. Unless it's been polished, the concrete is quite absorbent and makes a good ground. Depending upon the ink you use, the results might be transparent or opaque. Once the ink is dry, you can use other media to add more color to the design.

All of these media listed above are quite durable and could be left without an additional topcoat, though I like to add wax finish like Renaissance wax if I'm not finishing with epoxy resin.

You can also achieve beautiful results with watercolors and powdered pigments. However, these will need a protective top coat, like resin, to make them permanent.

Breakage

Sometimes pieces break, either removing them from the painter's tape, or during handling. The good news is you can almost always turn the breaks into a design feature. Here are a few suggestions of ways to work with breakage:

Embed the pieces in fresh concrete, perhaps of a constrasting color. Offset the pieces so that the cracks are visible - don't try to hide them. This works quite well when the original piece broke because they were too thin.

Use epoxy putty to reattach the broken pieces. The putty comes in a range of colors and can be sanded and shaped just like concrete once cured. Encapsulate the pieces in resin. Here I generally try to minimize the space between pieces as any gaps will be transparent. You could also use that transparency to your advantage.

Next: Concrete Cabochons Part Three: Epoxy Resin Topcoats