Doming is how you give a flat resin piece a smooth, rounded, glassy top. You pour a thin coat over the surface and spread it right up to the edge, and surface tension holds it there in a gentle dome. No mold and no tape are needed.
Deby of Deby at Mixed Media Arts shows the technique on the back of a resin petri coaster. Cast pieces nearly always cure with a small sharp ridge around the back, because resin creeps up the sides of the mold. A cork backing would hide it but would also block the clear parts of the design. A domed coat fixes the ridge and leaves both sides glossy.
Why resin domes instead of running off
Resin goes where resin has been. As long as the liquid stops at the edge, surface tension holds it on top and it settles into a slight curve. The moment one spot goes over the edge, the resin has a path, and the rest follows it down the side. That is the whole skill: get to the edge, never past it.
What you can dome
- The flat back of cast coasters and paperweights.
- Pendants, cabochons and charms.
- Photos, stickers and paper pieces sealed first with a thin coat of glue or resin.
- Painted wood slices and small tiles.
Small and round is easiest. Square corners are harder, so take extra care at each point.
How much resin to mix
Very little. Deby mixed about 10 ml for a coaster back and had some left over. A thin dome on a 4 inch piece needs less than you think, and a too-full pour is the main reason resin spills over. Measure by volume or weight as your resin kit says, and mix slowly for the full time. See how to mix epoxy resin if you are new to it.
Set up for a clean dome
Raise the piece on a cup or a block smaller than the piece, so any drip falls away instead of pooling under the edge. Check the surface is level; resin self-levels only on a level piece. Work in good light and look across the surface from the side so you can see exactly where the wet edge is. Wear gloves and work in a ventilated room.
Doming vs a flood coat
A flood coat is poured on a bigger flat piece, like a tray or a painting, and is allowed to run over the sides, often with tape underneath to catch the drips. Doming is for small pieces where you want a clean edge with no drips at all. It uses far less resin and leaves a rounded, lens-like top that makes colours look deeper. Doming resins and UV resins are thicker and hold a taller dome; a thin coating resin gives a flatter curve.
Troubleshooting
Resin ran over the edge. Wipe the drip off the side with a gloved finger and pull the edge back with the straw. Less resin next time.
Bare spots that will not fill. Grease from fingers stops resin sticking. Clean the surface with alcohol before you pour.
Tacky after a day. The mix was off. How to fix sticky resin covers the fix.
Bubbles in the cured dome. Pass a flame over it sooner, and keep the resin warm before mixing.
Want the coaster itself? Start with how to make resin coasters and how to use resin molds, then dome the back with this method.
