Mixing Instructions for Epoxy Systems
Tacusil® epoxy systems are typically in a two-component format containing a resin and a hardener. The resin can be a thin liquid or can be highly viscous. The high viscosity resins contain fillers, which can settle to the bottom of the container. A resin that has settled out will need to be mixed to a homogeneous consistency prior to introducing the hardener. Hardeners are usually a polyamine, but can also be an anhydride. Hardeners may also require mixing before use if settling has occurred.
Things to consider prior to mixing your epoxy system regarding surface preparation:
● Oil and dirt can cause adhesive delamination
● Surfaces whenever possible should be abraded with sand paper
● Some plastic surfaces may also require flame or corona treating to remove any plasticizers
Mixing the Epoxy System
After creating a homogenous resin and hardener, blending of the A/B system can occur:
● Measure out the part A to be blended to the nearest gram.
● Add part B using the same weighing procedure.
● Mix the A/B system for at least 3 minutes, scraping along the sides and bottom of mixing vessel.
● Upon completion of a thorough mix, degassing may be required to minimize air entrapment or bubbles. It is recommended to pull a vacuum of at least 28" Hg for about 5 minutes.
Reaction rates are typically stated in the technical data sheets as a temperature/mass variable. (ex: 25 minutes / 100 grams). If you are creating a larger mass the reaction rate will be shorter because the system will generate its own heat. Lower masses or a thin film will have a longer rate. If your starting temperature is higher than what is on the TDS your reaction speed will also be faster.
Epoxy System Molding
If you plan to mold with an epoxy system, a typical mold is made from RTV silicone and will require a mold release to be applied prior to molding with the epoxy. The silicone molds without a mold release will bond to your epoxy casting.
An option to not having to use a mold release is to have a mold made from urethane:
● If you are spraying on a mold release, spray both the inside and outside of your mold before baking the mold in an oven. Baking helps to thin the mold release and seal any pores in the mold.
● After baking, wipe out the excess mold release and then re-apply a very thin coat of mold release prior to casting your mold.
Another option is to use Johnson's Paste Furniture Wax. The wax can be applied to a warm mold and will provide the needed barrier protection between your mold and the epoxy casting. The wax can also be mixed with mineral spirits to create a spray mold release.