Cast Your Treasure in Plastic Resin

Gather up your favorite objects and then follow these instructions for sealing them in plastic resin.
Table of contents

Cast Your Treasure in Plastic Resin


A catalyst is a substance that causes or accelerates a chemical reaction without being permanently affected by the reaction.

Crafty Clues

When you're working with resin casting, make sure that you measure your plastic and catalyst carefully. If the directions say 45 drops, make it 45 drops! You may also have to make some adjustments depending on the room temperature in which you're working. Also, keep you work area clean. Dust will get into the mold and become a permanent part of your project. You can cover the mold with plastic wrap while you're wating for the layer to harden to help minimize dust and debris. Make sure your containers and molds are clean, too.

A craft more suitable for older children (age eight and up) is acrylic resin casting. This craft allows you to embed or encase just about anything in a clear plastic shape.

Some items your child might enjoy casting are pieces of colored glass, coins, dead insects or other natural specimens, marbles, leaves, pressed or whole flowers, hardware or parts like nuts and bolts, rocks, seeds, beans, grains, shells, old jewelry or watch I said, just about anything.

Even photographs can be encased in plastic, but you'll need to seal them first to protect them. Coat them with a sealant known generically as a vinyl resin glue/sealer, allow it to dry, and then embed the object in the resin.

Here's what you need to begin acrylic resin casting:

  • The plastic resin
  • A catalyst
  • An eyedropper to dispense the catalyst
  • Some disposable (unwaxed) cups to mix it in
  • Some popsicle sticks to mix it up
  • A mold (available from your crafts store, or youcan make your own)
  • The items you want to embed
  • Mold release to make it easier to get the hardenedcasting out of the mold (optional)

To begin experimenting with plastic resin casting, I suggest you buy your first mold at the craft store. I also suggest you start with a single-layer casting; smaller projects are probably the easiest to begin with. Here are the basic instructions:

  1. Follow the instructions on your containers of plastic resin and catalyst and mix the exact amounts of casting plastic and catalyst for the first layer.

  2. Stir well using your wooden stick. Try to "cut through" the liquid and introduce as few air bubbles into the mixture as possible.

  3. Pour the liquid into the mold to form the bottomlayer of the casting.

  4. Let the first layer set until it's rubbery. Poke it lightly with a wooden stick to make sure it's ready. (Don't use your finger as you may embed your fingerprint!) It's ready when it is about as firm as set Jell-O and doesn't stick to the stick.

  5. Carefully lay the objects you want to embed on the base layer. Before you place them, decide which side of the casting you want them to be facing.

  6. Mix the plastic and catalyst for the next layer. The instructions for mixing the second layer may be different than the first, so read the directions on your containers carefully. The proportion of catalyst to plastic usually changes with succeeding layers.

  7. Continue mixing, pouring, laying out your objects, and allowing the layer to set, according to package directions, until you're finished.

  8. Let your casting cool completely (from four to 24 hours) and then pop it loose from the mold. You can tell it's set when it makes a clicking sound when you tap it with your wooden stick.

  9. Smooth off any rough spots that may be left on the casting with a medium-grade file. Do this very gently. Sand the casting with a very fine sandpaper by laying the sandpaper on a flat surface and moving the casting over it.

  10. Buff the casting with a soft cloth (or buffing wheel) and plastic buffing compound.

You can add dyes or pigments to color your resin casting, but only use those specially formulated for use with polyester casting resin. Dyes are usually transparent and pigments are usually opaque.

Be sure to clean your molds carefully (the same is true for all molds, including candle molds) so you can use them again. Don't use steel wool or scouring powder. Even a sharp fingernail can make an indentation in a soft polyethylene mold. If you do scratch or dent a mold, get rid of it and start with a new one. Always look molds over carefully in the store for imperfections.

If you want to move on to advanced casting, you can try creating your own molds. Molds can be made from a variety of materials: oven-proof glass (like Pyrex), certain rubbers and plastics (poly plastic molds are among the easiest to work with), metal, aluminum, and stainless steel. You can pour your mold so that multiple objects are all embedded on the same level, or do a multi-layer pouring, where you allow each layer to gel before adding more objects and pouring again. The multi-layer technique gives your piece a feeling of depth and interest.

Resin casting is a great way of taking what seems like just a lot of clutter, souvenirs, or small collections, and making them into something both useful and pretty to look at.

A good booklet to get you started with plastic resin casting is the Castin' Craft Idea Book by Casey Carlton. Your local crafts store should have all the supplies you need, too. The ones I use are called Castin' Craft brand and they're from E.T.I. in Fields Landing, California.