SHELLAC is used before painting on wood to seal knots and resin coatings, and to cover discolorations of the painted surface.
Available in 0,25 litre tin canisters. Where to buy.
Shellac must have 99.5 % alcohol as solvent. Weaker alcohol, e.g. 96 % rubbing alcohol contains water that remains when the alcohol has evaporated and the shellac has settled. The water creates pores through which resin bleeds through.
Pour a small amount of shellac at a time in a disposable container. Use a simple brush - containers and brushes used cannot be cleaned. Apply evenly. Ingredients: isopropanol, shellac flakes.
Time needed to dry: half an hour to an hour.
WARNING: highly flammable liquid. Do not expose to heat, sparks, fire or hot surfaces. No smoking.