Casting resin's curing process is caused when heat is generated by the chemical reaction that takes place when catalyst is added to casting resin. Keep this in mind when reading through this bulletin and working with Castin'Craft Casting Resin.

Casting Resin is sensitive to environmental conditions like humidity, heat and cold. If the room your working in is below 65 degrees F, it will slow down the curing; if the room is over 75 degrees F, it will accelerate the curing and can cause yellowing and/or cracking. Humidity can cause cloudiness in your casting. Casting resin curing is also affected by the type of mold, the amount of catalyst and additives like pigments, dyes and Surface Curing Agent.

An important thing to remember with casting resin is the thicker the layer, less catalyst is needed; the thinner the layer, more catalyst is needed. The label recipe is very conservative in the drops of catalyst to be added.

The best molds are made from HDPE (High Density PolyEthylene plastic). Using molds made of HDPE result in the clearest castings. Tupperware and Rubber Maid containers are made from HDPE. The ratio of catalyst verses casting resin shown on the label has been formulated for these types of molds. Another advantage to using these types of molds is that no mold release agent is required.

Latex or rubber mold compounds, RTV compounds, Silicone and Polysulfide compound molds bring their own set of advantages and disadvantages. A mold release agent is not needed with these types of molds as they are very flexible. The biggest disadvantage to flexible molds is that castings come out tacky and wavy because heat from the resin when curing dissipates quickly through the rubber molds. There are two methods you can use to help the curing process. Either increase the heat in the area the casting is curing in or increase the catalyst to intensify the chemical heat. To heat the area the casting project is in, you can use a regular oven, making sure you keep the temperature below 100 degrees F, or you can build a light bulb oven using a cardboard box and a light fixture with a 60 to 100 watt light bulb (no higher due to fire risk). After pouring your castings, place them in the oven for at least 12 hours. If the casting is still sticky, return it to the oven until dry. Another way to aid the curing process is to increase your catalyst amount to one or two per fluid ounce of resin depending on the thickness of the casting. Experiment to get the best results.

Glass & Metal Molds: When using glass or metal molds, a mold release agent is necessary. Use a commercial mold release agent like P.V.A. (Poly Vinyl Acetate) mold release and follow the directions on the container or use Pam cooking spray applied to a paper towel and wipe inside the mold. Another simple mold release is to mix 1 part liquid soap to 4 parts water. Apply to mold and allow to dry.

Plaster, Cement and any porous type Molds: These types of molds need to be lightly sealed with paste wax. The amount of catalyst should also be reduced due to heat build up within the mold.

There are several things that can be done when a casting has a cloudy surface. The first involves sanding with 120 grit sandpaper, then 400 grit, followed by buffing with a buffing compound or Jewelry's rouge. You can also lightly sand your casting and then finish with a solvent based clear acrylic spray. Note: Do not use Surface Curing Agent or paste wax type mold releases when attempting to achieve a clear casting. Both products contain wax which will mix into the casting resin and cloud it!

When simulating water in a vase there are a couple of things to keep in mind. Casting resin shrinks by 7% on average. This figure is affected by how much catalyst is used, the type of vase, the temperature of the room, if rocks or marbles are added, how deep the resin is poured and the diameter of the vase. To keep the shrinkage to a minimum, reduce the amount of catalyst used.

When using pigments & dyes, remember that the curing process will be slowed down, so add extra catalyst. A piece of clear plastic wrap stretched over the surface but not touching will help to cure the surface.

Surface Curing Agent is an air dye wax which when mixed with casting resin, floats to the surface and seals of the air/humidity, resulting in a tack free surface. Note: when making a totally clear cast, surface curing agent is not recommended as it will cloud your casting, instead stretch clear plastic wrap over the surface but not touching. This will seal off the air/humidity resulting in a tack free surface.

Remember, due to the nature of casting resin, consistent results are obtained through attention to detail. Never place one of a kind objects in casting resin, because once in, it is almost impossible to remove. Always practice before doing your final piece. Start small and work up to larger items so you can become comfortable when working with casting resin.