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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.
Supplies - Sanding
- Coarse Sandpaper - 80 or 100 grit
- Fine Sandpaper - 150 or 220 grit
- Wet/Dry Sandpaper - 400 & 600 grit
- Sanding block - optional (mine is approx 100 grit)
- Dremel tool with drums sander or other sanding/grinding attachments
- Dental Pick, fine awl, or other sharp pointy tool
- Dust Mask
- Safety Glasses or goggles if using Dremel Tool
- Wide-mouthed jar/container with clean water
- Clean water or dye liquid
Looks pretty sad at this point
Sanded edgeds and front to expose beads
Dunked in water to remove dust and preview epoxy finish
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
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.
- 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.
Supplies - Adding Color
Gather a selection from the following:
- Acrylic paints (I use burnt umber & a number of Daniel Smith's duochrome metallics)
- Rub n' Buff decorative wax
- Pitt Artist Pens
- Powdered pigments
- Stamps & Stazon stamp pad(s)
- Assorted, inexpensive acrylic brushes
- Gloves - optional
- Water jar for rinsing brushes
- Paper towels
Blank back of cabochon, with a dollop of acrylic paint
Acrylic rubbed into concrete, then buffed off
I scribbled over the acrylic base with Pitt artist pens
Then rubbed them off before they dried so they simply cast a glow of 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.
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.