Put on a vapor respirator, safety goggles and latex gloves, if you are not already wearing protective gear. Make sure that your work area is well-ventilated.
Take a clean rag and wipe away as much of the polyester resin as you can while it is still wet. Do not spread the resin to other surfaces. Put the rag in a safe place away from any possible fire sources.
Pour a small amount of acetone onto the stained surface, while the polyester resin is still wet. Let the acetone soak the resin for a moment, so that the resin dissolves. If you are removing resin from an object, you can pour acetone into a bucket and immerse the object in the bucket. When finished, save the used acetone for another project.
30 kgs plastic drum
165 kgs drum