Mold-Making.com

How to paint plastic castings by painting the mold instead of the casting.

Two-Part Mold demonstration

How to make Fake Rocks

How to "Shrink" an object

How to Slush Cast Plaster

How to Slush Cast Plastic Resins

How to "Print" on plastic

How to make "Sandstone"

How to make Self Hardening Clay

How to make a simple Clay Roller

How to Dry Brush

For more how-to, visit www.castcraft.com

Castcraft Books and Videos show:

  • How to make molds:
  • concrete molds
  • plaster molds
  • RTV rubber molds
  • latex rubber molds
  • silicone molds
  • polyurethane rubber molds
  • How to make a vacuum forming machine
  • How to make a concrete birdhouse
  • How to make concrete pots or concrete pottery and concrete bonsai pots
  • How to make latex rubber masks
  • How to sculpt
  • How to make props
  • How to use polymer clay.
  • How to make injection molding molds
  • How to make an injection molding machine
  • How to melt metals
  • How to melt aluminum, brass, bronze, iron
  • How to make sand molds for metal casting
  • How to make sand molds for concrete
  • How to make a trellis from copper pipe
  • How to use a centrifugal casting machine

HOW TO COLOR PLASTIC RESIN PRODUCTS
"IN THE MOLD"


A quick demonstration of in-mold painting you can do for yourself: epoxy resin cast into a plastic butter-tub lid. The resin picks up the painted image completely.

You can apply surface color to castings made from any liquid plastic resin such as Polyester, Epoxy, or Polyurethane Plastic at the same time you make the casting.

It is best to use a rubber mold for this technique. Polyurethane molds are preferred - they won't be harmed by spray paint, and the paint can be evenly applied to the mold. Silicone molds will also work, but since Silicone repels some types of paints, you may not get an even coat. Latex rubber molds will work, but the solvents in some spray paints may damage the mold.

It's extremely easy - simply spray paint your mold with the color of your choice before you pour in the liquid casting resin. You can use acrylic or oil base spray paints. Do not use a release agent - in most cases the spray paint will also act as a release agent. (You can also apply paint with a brush or even a rubber stamp if you prefer).

Let the paint dry, and then mix and pour the liquid resin as usual. As the resin cures, the paint on the surface of the mold will actually become part of the surface layer of your plastic casting.

When the plastic has cured, remove it from the mold. The surface layer of the casting will be the color of the paint.

If you want to test this technique and see how well it works before actually using one of your molds, try this:

Get a plastic lid from a grocery product that has a colorful design on it. Lids from butter tubs are ideal. (The lid should NOT be made from styrene if you are using polyester resin.) Mix and pour the plastic resin of your choice over the colored design. Let the resin set, and then peel the cured plastic off the lid. The result will be a plastic casting with a high quality reversed image of the design embedded in the surface. Rub over the design with your fingernail and you will see it is much more durable than any type of painting would be.

You can make images like this by painting, silk screening, or rubber stamping images onto the surface of your mold, before pouring the plastic resin. You can also use inkjet or laser-printed images - see this technique.

There are several advantages to in-mold painting:

1) The color layer in your casting will be very durable - it has actually become part of the plastic. It is much more durable than it would be if you cast the product and then painted it.

2) If you had previously been coloring your entire batch of plastic resin with color pigments, you will save a lot of money. By spray painting the mold, you only color the top layer of the casting, not the entire casting.

3) The finished casting will appear to have a very even coat of color, even if you didn't paint the mold evenly.

4) You can also decorate the surface with other materials, using similar techniques. Try spraying a mold with a clear acrylic spray and then immediately dusting it with glitter or fine sand, for instance. The surface of your finished casting will include the glitter or sand.

5) You can use spray paints such as "chrome" or "brass" paints to get the look of metal. Or use the new "granite" or "marble" spray paints to get those effects.