Casting Epoxy Basics

Casting epoxy curing time is longer than curing time of any of the coating resins. This is done on purpose to facilitate bubble release from inside of the casting and to give the material enough time to dissipate the heat into surroundings.

Viscosity can be described as an opposition to flow of the material. Low viscosity means that the liquid epoxy will flow faster, fill voids easier and better release the air. It is especially important for casting resin because mixing Part A and Part B introduces air into material, and, due to the relatively high thickness, degassing heavily relies on the viscosity of the resin.

Casting Resin should be used in temperatures 20-25°C. Temperatures below 20°C cause a significant increase in the mixed viscosity of the epoxy and slow down the chemical reaction, thus worsening the air release and prolonging cure time. It is also possible that at low temperatures curing reaction can stop incomplete, causing reduction of the properties such as hardness and glass transition temperature. 

Mixing time greatly depends on the volume of the pour and tools that are used for mixing. We suggest using hand tools for smaller pours up to 1L and mechanical stirrers for large volumes of resin. 

Mix resin and hardener for 5-8 minutes, scraping sides of your mixing pail to avoid leaving poorly mixed resin and hardener in your project. The good indication of properly mixed resin is the absence of cloudiness and paths that your mixing equipment leaves in the bulk of resin, see picture below: 

When you reach homogeneous state in your epoxy, and it looks like one homogenous mixture, then keep mixing for 1-2 more minutes and you should be good to proceed to pouring your product into a mold. 

Check out our casting thickness tips video to get a sense of our Casting Epoxy performance at different volumes and shapes.