The purpose of this study was to determine how resin, a side compound of wood, and resin cleaning methods affect the adhesion strength of water-based varnishes. For this purpose, scots pine (Pinus sylvestris L.), black pine (Pinus nigra subsp.), larch (Larix decidua Mill.), and spruce (Picea abies (L.) H. Karst.), woods with different amounts of resin in their anatomical structure were examined. Physical and chemical resin cleaning procedures were applied to the samples using acetone, cellulosic (lacquer) thinner, sodium hydroxide (NaOH), sodium hydroxide + hydrogen peroxide (NaOH + H2O2), and soft soap chemicals. Later, single-component and double-component water-based varnishes were applied to these sample surfaces. The samples were then subjected to a hot and cold-check test in accordance with the principles set forth in ASTM D 1211 (1997). In the examples, the changes in adhesion strength were examined according to TS EN ISO 4624. According to the results, resin cleaning chemicals and methods reduce the adhesion strength of water-based varnishes.