Epoxy coating: a smooth surface on a print

What it is

Epoxy resin is a two-part compound that cures after being mixed with a hardener. Its properties are described on Wikipedia and in the article on Epoxy. For prints, self-levelling liquid epoxies with a working time of a few tens of minutes are used.

The coat floods the layer lines after printing and, once cured, forms a hard glossy surface. Besides the looks, it increases resistance to moisture and minor scratches.

How it is applied

• Preparation. Sand the surface and degrease it, see sanding.
• Mixing. Keep to the maker's ratio, a wrong ratio stays tacky.
• Thin coat. Apply with a brush, let it flow out evenly and keep turning the part while it starts to set. A thick coat forms drips.
• Safety. Gloves, ventilation, and a respirator if needed. Not everyone tolerates it, it can cause an allergy.

Limitations

Epoxy adds thickness, so it is not suitable for precise parts, threads and snap-fit joints. Fine detail and text get flooded. Do not rely on the coat being food safe unless the maker says otherwise. We do not offer this finishing as a service, parts arrive as the printer prints them.

Apply it at room temperature and cover the part while it cures, otherwise dust is caught in the liquid layer. Curing takes several hours to a day depending on the type of resin. A cured coat cannot be undone, so try the procedure on a test piece first.

When ordering

If you plan to use epoxy, choose the strength according to the use and expect the final surface to be a little thicker. The alternative for a smooth surface without epoxy is acetone smoothing, but that works only on ABS and ASA, which we do not print.