I started making the oval key chains last year for the Kansas City Teddy Bear Jubilee show my sister attends, so I was interested in expanding beyond the patterns Steve had supplied to other topics and designs. Since I am not an artist, I first needed to find images to use. One of my favorite image sites is Open Clip Art. These images are public domain, so they can be used on items for sale. I use Inkscape to transform the images from solid silhouettes to outlines when needed and Microsoft Publisher to fit them into the oval or arrowhead shapes. I also get images from other scroll saw patterns and adjust them as needed to make the key chains. For example, I wanted more dog breeds, so I copied the images from the Christmas tree ornaments and resized them for the key chains:
My favorite wood for the front of the key chains is 1/8" thick maple. The grain pattern is light enough to show off the image and intricate details can be cut without breaking or chipping. I stack 2 or 3 layers together and secure with masking tape. I put the patterns on the top of the stack and drill blade entry holes. Even drilling into a wood backer can leave rough drill exit holes, so I sand the back before sawing to keep from dragging on or scratching the saw table.
I cut the interior design using a 2/0 blade. I do not cut or drill the hole where the key chain hardware is attached. Since I use mostly scrap wood for the back, I next rough cut around each key chain leaving about 1/8" of waste material. If I have a large enough piece of backer material, I sometimes omit this step.
The top layer of the stack still has the pattern, but the lower layers do not. I use a template cut from 1/8" clear acrylic to draw the key chain outside edge on the lower layers of the stack.
I then glue the key chain fronts to the backing wood. If I plan to use clear epoxy to fill the image, I choose a highly contrasting wood to use for the back such as cherry, walnut, mahogany, bubinga, Spanish cedar, or cocobolo. I pretty much use any 3/16" or 1/4" scrap wood I have available. If I plan to use granite powder or colored epoxy for the image, I often use oak for the back. I use a small paint brush to carefully apply the glue and make sure none has squeezed out into the image. I use a toothpick to clean up any excess glue. I clamp the two layers together for about 30 minutes.
I then cut the outside edge of the key chain and drill the hole for the hardware. I use an oscillating spindle sander to round over the bottom edge and smooth the curves.I apply a gel urethane with a small craft paint brush to all surfaces and edges of the key chain, being especially careful to make sure the entire interior cut edge is coated. The wood needs to be sealed completely or it will release bubbles into the epoxy as it is curing. Penetrating oil does not work to seal the wood. I then remove any excess urethane and let dry for at least three days.
Next, I fill the interior design with epoxy. When finished, the key chains have a smooth surface and won't catch on clothing or items and break the fragile design edges. I first place freezer paper on my work surface and then a plastic lighting grid from a home improvement store. If any epoxy drips over the edge, the grid makes it easier to remove the key chain when cured. I carefully follow all the instructions for the epoxy, carefully timing both mixing stages. I use plastic medicine cups to measure, plastic bathroom cups to mix in, and skinny wood sticks to stir. I also use the bathroom cups to divide up the epoxy to add different colorants.
If I am using granite powder, I add enough to get a consistency similar to oatmeal. The particles in the powder want to settle out to the bottom, I have found that I need to add a lot to counteract this. I make sure I have overfilled the image. It will shrink a little as it cures, and some will be absorbed into any wood that was not thoroughly sealed. There will be bubbles in the epoxy when it is first mixed, but they will rise to the surface and pop on their own. Occasionally bubbles will get caught in narrow cuts, but they can be popped or removed with a straight pin. A scrapbook embossing tool can also carefully be used over the epoxy to pop bubbles.
I then cover the poured epoxy with upturned plastic storage boxes as soon as possible to prevent dust and pet hair from settling into the epoxy and allow to cure for about 4 to 7 days. The longer they cure, the harder the epoxy gets, which helps keep it from getting deeply scratched during the next sanding step.
After the epoxy is cured, I use the oscillating spindle sander to remove any excess epoxy on the top surface and any that has dripped onto the sides. Turning the key chain often helps keep the top flat. When all the excess epoxy is removed, I round over the top edge and finish sand by hand with increasing fine sandpaper. I try to remove any obvious scratches in the epoxy, but it is impossible to remove all traces of scratches on the epoxy. The sanded epoxy also will have a matte finish instead of the shiny finish it had when poured.
Finally, I use dusting cloths such as Swiffer or Pledge to remove all the sanding dust and finish with two coats of urethane gel, wiping off the excess and allowing a few days between coats.
Steve recommended using Inlace or polymer clay for the interior design. Inlace is very expensive and difficult to find and I didn't really like the results I got from using polymer clay (the dolphin below), so I decided to use a casting epoxy. I use Easy Cast which is low odor and mixed in equal proportions. I also use their faux granite powders. I also tried using their colorants, but the color absorbed into the wood and left stains on the surface. If I want a solid color, I found that scrapbooking pigment powders such as Pearl Ex work, although unpredictable patterns sometimes develop during curing as with the tropical fish.
The guitar is filled with Pearl Ex pigment powder mixed with a darker blue embossing powder to give it a little texture. Embossing powder will not dissolve in the epoxy, so it can't be used for solid color.
The shark uses black quartz granite powder and the sea turtle is Appalachian green granite powder.
Most of the dogs, like the lab below, use clear epoxy and contrasting wood backgrounds which show through the epoxy.