You can create beautiful stained glass effects in your scroll work by using colored polymer resin. The resin we are going to use here is Envirotex Lite by Environmental Technologies Inc. and is available at many hardware stores and craft stores. You can get more information on this product on the web at http://eti-usa.com/envirotex-lite/ . This resin is typically used as a pour-on protective finish for countertops but will work fine for small scroll work as long as we don't try to pour it too thick.
To color the resin, we are going to use DecoArt Americana acrylic paint which can be purchased at most craft stores. Many polymer resins react and won't cure properly with water or water-based paint mixed in, but Envirotex Lite will work fine with the small amount of paint we will be using. Different colors of paint will have varying amounts of opacity but with most colors, 2 to 5 drops of paint per ounce of mixed resin should be enough for a semi-transparent look. If you want a solid fill, you will have to chose an opaque color and use a couple more drops per ounce. You can find an opacity chart for DecoArt paints on the web at http://www.decoart.com/Tips/downloads/americana-opacity-chart.pdf . This will help you chose the right color for your goals.
You will want to chose a design that doesn't have any scrolled veining lines since the resin may not be thin enough to flow all the way into the veining and your project may not turn out right. It is also worth noting that you should not use a porous wood such as red oak since the resin will flow through the pores which can be a little messy as shown in the following figure. This is should not happen with white oak, but to be safe, it would be best to use a tighter-grained hardwood.
Click on this image to go to the product page for this pattern
Before you begin with the resin, you must make sure your scroll work is properly prepared. If you have planer marks, tearout, or any unevenness, you will want to sand that off. The resin flows very freely and will leak out anywhere that it can. You will also want your wood to be a little thicker than your desired finished thickness since you may have to sand off 1/8" of an inch or more of thickness after your resin hardens. Once your project is sanded, you can clean the dust off and begin covering the back of it with a layer of packaging tape. A good brand of thick packaging tape will be much easier to use for this than cheap stuff.
Important:Be sure to not get any ridges or bubbles when you lay the tape down. Then you can use the edge of a plastic card all over the tape to be sure it is stuck to the wood everywhere, especially where it overlaps another piece of tape and where the wood is thin.
This image shows what can happen if
the wood you choose is too porous
Prepare you work piece by sanding off any
tearout, unevenness or planer marks
Be sure the tape is really stuck on good
by using a plastic card over its entire surface
Next you can mix the resin as per the manufacturer's supplied instructions. Be sure to use measured equal parts of resin and hardener and mix well. Halfway through your stirring, I recommend you pour the mixture into a second clean mixing cup and continue stirring. This ensures that there is no unmixed resin along the walls of your cup when you pour. After you resin is mixed, add a few drops of your color and stir it in thoroughly.
Possibly the hardest part of all of this is to mix the right amount of resin and to use the right amount of paint. It's something you will start to get the hang of after a couple projects. It is best to mix more resin than you need since you will not be able to perfectly match your color if you need to make more. If you do run out of resin, I recommend immediately mixing another batch and match the color as closely as possible. If you wait until the resin is cured to make another batch and add to it, you will see lines between your two batches.
Be sure to mix equal parts of resin and
hardener and mix thoroughly
After mixing thoroughly, add just a few
drops of paint
Just a few drops colored the entire
batch of resin
Now place your project in a foil tray in case of leakage, and begin pouring your resin into the fretwork. You may want to put something under the project to keep it up off the base of the tray in case you leak a lot of resin. If you are careful, you can pour the resin very accurately and not make much of a mess. Try not to get any on the outer edges of your work piece as you may have a hard time getting it off later. If resin drips down the side of your mixing cup, wipe it off to prevent it from dripping where it isn't wanted. Pour until your fretwork is full or almost full, but try to avoid having it overflow if possible. The only real problem with overflowing is when the resin drips down the side of your wood in a place that will be difficult to sand later. You will have to sand the whole piece down to the lowest point of resin later so fill all your fretwork as much as you possibly can. If you have any really sharp corners or narrow cuts, you can poke around carefully with a toothpick to be sure there are no air pockets underneath the resin. Just don't poke a hole in your tape.
Pour slowly, being careful not to overflow
onto the sides of your project
You can use a toothpick to gently poke
air bubbles out of any tight corners
After the resin sits for a few minutes, you will see a layer of bubbles forming on the top. You can help get rid of the majority of these bubbles by doing a quick pass with a small propane torch. (Important: Be sure to follow all appropriate safety measures when using a torch!). Set the flame quite low and be sure to pass over the resin quickly so as to not scorch your work. Keep a little distance and don't touch the flame to the resin, as this will cause a layer of skin to form. Not much heat is needed to burst the bubbles and if you wind up heating the wood, you will actually introduce more bubbles into the resin by expanding the air in the wood. You can repeat this in another half hour if you think it's required, but you may not need to.
Use a small propane torch at a safe distance
to pop the bubbles on the resin's surface
Very little heat is required. The lower half of the
cross shows how it will look after applying heat
Set your project aside somewhere very flat and away from dust. You can now clean up with alcohol. The mixing cups can be saved for re-use by pouring out the remaining resin and wiping them out with paper towels. After you wipe out most of the resin, you can then use a small amount of alcohol to clean out any remaining resin again with paper towels.
Allow the resin to cure for at least 24 hours. Once it is cured, you can remove the tape as much as possible and begin sanding the project until it is flat. If the resin settled or leaked, you may have to remove a lot of material. If it leaked too much, your project may not be salvageable. You can used an orbital sander with coarse paper or a belt sander if you are careful to sand evenly and keep a firm grip on your project. If you use a belt sander, you will have to graduate to the orbital sander afterwards to remove the scratches. Work your way up to 320 grit paper. You will still see light scratches in the resin after 320 grit paper, but your varnish will fill these in and hide them as long as they are fine.
After you are done sanding, you will still see occasional small bubbles in the resin. This can't be avoided completely, but you can make them much less noticeable by blowing the dust out of them with compressed air. If the dust is stubborn, you may need to poke it with a pin to loosen it up.
Once you have gotten the dust out of all the bubbles, you can apply several coats of your spray varnish of choice. I have only tried spray poly varnish over the resin so if you are using another type of varnish, you may want to test it on some leftover cured resin before using it on your project.
Use a small pin and compressed air to poke
and remove dust from any remaining bubbles
There are so many ways you can add variety to a scroll saw project with this resin. The above example is just the most basic of applications. You could use multiple colored resins and swirl them slightly for marbled or blended effect. You could return to the scroll saw and cut out some more fretwork and refill with another color of resin after the first color cures. You could also just pour a flat sheet of resin in a silicone baking pan to use as a backer behind your scroll work. This would allow you to blend multiple colors in one layer to make a beautiful sky background. You are only limited by your imagination.