Resin is perfectly normal and unavoidable on a wood surface. Wood can secrete resin during the first year. Fresh resin stains can be removed with white spirits. When resin surfaces, it quickly becomes brittle and often falls off spontaneously. It can also be removed with a plane. A crystalline resin may appear on the surface of certain types of hardwood during warm periods. This process stops over time. The resin crystals can be removed with a hard brush or scraper.