Water Based Sanding Sealers:
If you are after a clear, very hard finish, with great buffing abilities, the water-based lacquers are hard to beat. This product consists of pellets of resin that are suspended in water and glycol ether solvent and are already cured. As the water evaporates, the slower drying solvents soften these pellets and they stick together, forming a consistent thin film over the entire surface.
Due to the hardness of a dried finish, the clarity of the finish, the buffing abilities and the relative lack of toxic fumes, this has been the finish of choice for a great many guitar makers and for mass-produced instruments as well.
Safety Precautions In Using These Products:
Many people feel that when they see the term ‘water-based’ attached to any finish material, it makes that product completely safe and eco-friendly.
While there may not be nearly the amount of fumes (VOC’s or volatile organic compounds), associated with these products as in the Nitrocellulose variety of lacquers, that does not mean they are any not less toxic. There in in-fact almost as much toxic qualities as in the solvent-based products. Its just that they are present, but in smaller quantities, and they are also diluted with water, rather than the solvent thinners.
Even though they are non-flammable (which is a huge plus), you should take the same safety precautions as you would with solvent based products. I.E. use adequate ventilation, wear approved respirator, use a separate spray booth for application and curing of the finish and avoid breathing the vapors as the finish dries. Also try to avoid contact with the finish while finishing, sanding etc.
Water Based Sanding Sealer – The Advantages:
- Tough, hard, shrink-free finish.
- Less toxic as compared to solvent-based finishes.
- Much easier clean-up.
Water Based Sanding Sealer – The Disadvantages:
- Many guitar builders including myself feel that the water-based finish does not enhanse the guitar tone in the same manner as does varnish or nitrocellulose lacquer. This can be a very significant point when applying to a fine, handmade instrument.
- Subsequent coats do not ‘melt-in’ in the same way as solvent based lacquers do.
- Due to the above qualities, when sanding the finish, if you sand through one coat and into another coat, you will see what is called a ‘witness line’. If you spray an additional coat, this mark or line, will disappear.