You can use window cleaner or rubbing alcohol. Simply wipe the tang down with your desired solution, and let it dry. Be careful not to handle the tang with your bare hands after this.  Rubbing alcohol will work the best, but you can use window cleaner too. You don't have to clean the wood scales. The wood is porous and textured, so it will take the epoxy readily. You can do this with a metal file or even a screw. You don't have to be precise for this step, but you should wipe the surface down once you are done.  If the scales are smooth on the marked sides, it would be a good idea to scuff them as well. You can also roughly sand the scales with 120-grit sandpaper. Make sure that you are only sanding the sides that will be touching the tang. Each brand of epoxy glue is different, but in most cases, you will need to mix equal amounts of "Part A" and "Part B" in a plastic, disposable cup. Work quickly. Most epoxy glues set within minutes.  Make sure that you are using epoxy glue, and not epoxy resin or coating. Mix the epoxy using a disposable tool, as it will ruin whatever you use to stir it. It would be a good idea to wear some plastic of vinyl gloves too. You can buy epoxy glue in hardware stores. Some craft stores may also sell epoxy glue. Use a disposable knife or paint spatula to spread an even layer of epoxy onto 1 side of the tang and the marked side of the matching scale with epoxy. Press the 2 together. Working quickly, flip the knife over so that you can see the other side of the tang. Insert the pins into the holes. Coat the tang and the marked side of the remaining scale, and press them together.  You may have to hammer the second scale into place to ensure a tight fit. If you want to, you can coat the pins with epoxy too. This will make the bond even stronger. Make sure that you are inserting the handle between the pieces of plastic wrap--this way, the excess epoxy won't get everywhere. Close the vise as tightly as possible. After squeezing the 2 halves together, all the excess epoxy will have leaked out. Dip a rag in acetone, and use it to wipe off any epoxy that has leaked out from between the 2 scales. How long this takes depends on the type of epoxy you are using. Some are set and ready to use within 1 hour. Others need up to 1 day to dry. Check the label on your package of epoxy for complete drying times and instructions.
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One-sentence summary -- Clean the tang on both sides to remove any oils or dirt. Scuff the tang on both sides to give the epoxy some texture to stick to. Prepare the epoxy glue according to the instructions. Glue the first scale to the the tang with the prepared epoxy. Insert the pins and glue the second scale. Insert the handle into the vise and clamp it shut. Wipe off any excess epoxy with a rag soaked in acetone. Allow the epoxy to set.

Article: Watercolors will give your design a muted, cloudy image, while acrylic paint will produce richer, more vibrant colors. If you want a more precise design that’s easier to control, use acrylic paint. If you like more abstract and blended designs, use watercolors. The way that these paints act on canvas or paper is similar to how they will react on your sand dollar. If you’ve painted with these mediums before, use your past experience to determine what kind of paint to use. You need water to clean off your brush when switching colors. You’ll also need to use water to mix and apply watercolor paint. When the water starts to get a murky brown or gray, empty the cup in your sink and refill it with fresh water. If you’re using paint from a tube, you’ll need a wooden, paper, or plastic palette to mix your paints. Unscrew the cap from the paint and slowly squeeze the bottom of the tube over your palette. Squeeze 1-2 drops of paint for every color that you want to use. You only need 1-2 drops of paint when starting off. Softly drawing an outline will help give you an idea of what kind of design you want before you start painting. After you're done creating the outline, you can fill in your drawing with different colors. Make sure that the end of your brush is fully saturated. You’ll need a decent amount of water to activate watercolor paint and keep acrylic paint from drying out. Take the brush and swirl it around in the paint to transfer it onto your brush. Once your brush is loaded with paint, you can start applying it to the sand dollar. Use small strokes at first to see how the paint reacts to the sand dollar. Follow along with the outline that you drew or follow the natural contours of the sand dollar. If you’re using watercolor, you’ll have less control over how the paint will react once it makes contact with the sand dollar.  Clean your brush in the cup of water before you switch colors or it could make your design look murky and brown. If you want to paint the top and bottom surface of the sand dollar, make sure you let it dry before flipping it over. If you're using acrylic paint, let the paint dry before applying a second coat so that the colors don't blend together. Sit the sand dollar out for 3-4 hours and let it fully dry. Touch the surface of the sand dollar to make sure that the paint has dried before handling it or you may smudge the paint.
Question: What is a summary of what this article is about?
Decide whether to use watercolor or acrylic paint. Fill a cup up with water and sit it next to your workstation. Squeeze the paint onto a palette if you’re using tubed paint. Create a design on the sand dollar with a pencil. Dip your brush in water. Dip your brush into the paint. Apply paint to the sand dollar with small strokes. Let the sand dollar dry.