Casting Treasures in Plastic Resin
When mixing resin make sure that you measure your resin and catalyst (hardener) carefully. If the polyester directions say 10 drops, use 10 drops! Adjustments may be needed depending on the temperature and humidity of the room you are casting in. Resin likes 70 to 75 degrees and low humidity. Resin does not like water or high humidity.
Cover castings with plastic wrap or plastic container so dust will not get into the mold and flaw your project.
Things you can cast in resin are unlimited. Here are a few ideas: pieces of colored glass, coins, dead insects and creatures, marbles, dried leaves and flowers, nuts and bolts, rocks, seeds, beans, grains, shells, old jewelry, watch parts, fabric, paper, photos and the list goes on. For paper and photos you want to use laser print on glossy text or inkjet print on high quality glossy photo paper. You can also seal them with Ultra Seal, which is made for resin. I like to coat my embedments with resin and let dry before putting in my resin casting. This also helps to fill the cavity voids of dried creatures so you can avoid bubbles when embedding.
Items you need to begin casting resin:
· catalyst or hardener (comes with the resin)
· disposable (unwaxed) cups or Reusable resin cups for mixing
· Some ResinObsession plastic Stir Stixs
· A Mold from ResinObsession or one you have made.
· Items to embed
· Mold release to make the castings pop out and to keep the molds in good condition.
Basic instructions, but please read the instructions that come with the resin:
1. Spray a light mist of Mold Release in mold and let dry.
2. Follow the instructions that come with the resin and catalyst (hardener) and mix the exact amounts. If using polyester resin mix amounts for first layer.
3. Stir well using plastic Stir Stixs. To introduce as few air bubbles as possible mix using a folding method (like folding whipped egg whites with batter).
4. Slowly pour the resin into the mold. If doing layers, this is the bottom layer of the casting.
5. Let the first layer cure to what is called a “gel stage”. Lightly touch with a Stir Stix to test. (Don't use your finger as you may embed your fingerprint!)
6. Carefully lay sealed or coated embedments on this first layer. Remember you are working upside down.
7. Mix resin and catalyst (hardener) for the next layer. If using polyester resin, read the directions on your containers carefully.
8. Repeat steps 2 thru 7 until you're finished.
9. Let casting cure completely and then pop it loose from the mold. Curing can be from 4 to 72 hours depending on temperature and humidity. If casting will not release from mold then it is not cured yet. You can tell it's set when it makes a clicking sound when you tap it with your Stir Stix.
10. Resin shrinks and can cause a “valley” or dip. Fill this “valley” with more resin or sand the edges with a fine grade (wet/dry) sandpaper or nail file. Very gently smooth off any imperfections on casting. One technique for sanding is to lay very fine wet/dry sandpaper in the bottom of a container with water and gently move casting over the sandpaper. This method is to keep the casting from getting too hot and melting and to control the dust generated from sanding.
11. Buff and polish the casting with a soft cloth (or buffing wheel) and plastic buffing compound.
If you want to add color
Add resin dyes (transparent) or resin pigments (opaque), specially made for resin, to
color your resin casting. You can also use powder pigment or chalk but make sure it
is thoroughly dry and using too much will make the casting soft.
Years ago ceramic and glass molds were used, dipping first in hot water then cold water so the casting would pop out. Many molds cracked or shattered using this method. Advancements have been made to the resin mold by using polyethylene plastic. For molding polyethylene, tiny suction holes must be made in the model to allow suction to form the plastic over the master mold. Sometimes these suction holes are visible on the polyethylene molds. These are not defects. To ensure molds stay in good condition for repeated castings, use mold release and clean your molds with soap and water. Although polyethylene has a natural chemical release quality, without mold release this quality will diminish. A sharp fingernail can make an indentation into a soft polyethylene mold.
You also have the option of making your own molds with RTV silicone or latex. Always test molds that are not made specifically for resin by putting a little resin on the back of the mold. Resin will become permanent in most candy molds.
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