Varnish is a transparent, hard, protective finish or film that is primarily used in wood finishing but also for other materials. Varnish is traditionally a combination of a drying oil, a resin, and a thinner or solvent. Varnish finishes are usually glossy but may be designed to produce satin or semi-gloss sheens by the addition of “flatting” agents. Varnish has little or no color, is transparent, and has no added pigment, as opposed to paints or wood stains, which contain pigment and generally range from opaque to translucent. Varnishes are also applied over wood stains as a final step to achieve a film for gloss and protection. Some products are marketed as a combined stain and varnish.
After being applied, the film-forming substances in varnishes either harden directly, as soon as the solvent has fully evaporated, or harden after evaporation of the solvent through curing processes, primarily chemical reaction between oils and oxygen from the air (autoxidation) and chemical reactions between components of the varnish. Resin varnishes “dry” by evaporation of the solvent and harden almost immediately upon drying. Acrylic and waterborne varnishes “dry” upon evaporation of the water but will experience an extended curing period. Oil, polyurethane, and epoxy varnishes remain liquid even after evaporation of the solvent but quickly begin to cure, undergoing successive stages from liquid or syrupy, to tacky or sticky, to dry gummy, to “dry to the touch”, to hard. Environmental factors such as heat and humidity play a very large role in the drying and curing times of varnishes. In classic varnish the cure rate depends on the type of oil used and, to some extent, on the ratio of oil to resin. The drying and curing time of all varnishes may be sped up by exposure to an energy source such as sunlight, ultraviolet light, or heat.
The wood should be clean, dry, smooth, and well seasoned. For best results use natural bristle brushes suitable for solvent-based products. For roller application use either foam or conventional short mohair type (such as Redtree Deluxe Mohair R-11PH) which must be solvent resistant. New Wood: Use of a marine teak cleaner or wood bleach is advised on new wood to remove excess oils, promote color uniformity, and adhesion. Follow manufacturer’s instructions for use and thoroughly remove all cleaner and neutralizer residue before proceeding. Rough sawn lumber must receive heavy sanding to level the grain. Work through the grits to effectively level the grain 60/80 to 100/150 to 220 and so on. When the grain is level, smooth sand the surface with 320 grit paper. Old finishes in good condition should be washed with Awlprep Surface Cleaner, then sanded with 220-320 grit paper to remove the gloss. Old finishes in poor condition should be removed. Test on a small area to make sure Awlspar doesn’t attack the old finish. If old finish is attacked, it must be completely removed. Note: Due to the wide variety of substrates, surface preparations, application methods and environments, customers should test the complete system for adhesion and compatibility under their conditions prior to full scale application.
Mixing & Reduction
New Wood Reduction: When finishing new wood reduce 100% (1 part M3131 to 1 part T0016 by volume) with T0016 for first coat only. This will allow the Awlspar to penetrate and seal the grain. For spray application reduce between 50-100% with T0180.
Subsequent coats should be applied with 25% reduction (T0180). Brush application: thinning or reduction is not normally required (after the first coat). If desired, reduce up to 20% with T0016. Stir only do not shake!
Awlspar Classic Spar Varnish can be used to seal wood and build up a complete finishing system. Alternatively, Awlbrite Quik-Fi Clear J3901/J3902 is a clear, fast drying wood grain filler that can be used to seal the wood prior to finishing with Awlspar M3131 (4-6 coats). See the relevant product datasheets for details. After new wood has been sealed, or on previously coated surfaces, apply light, smooth, even coats (2-3 mils wet) of full bodied material. At temperatures above 77°F (25°C), 2 to 3 coats can be applied per day. If sanding is required, allow to cure 24 hours before sanding. Best results are achieved when surface is sanded smooth with 320 -400 grit paper after every 2 to 3 coats. If building M3131 as a stand alone coating, repeat this process until the grain is filled and covered, 7-10 coats may be needed. Exact number of coats needed will vary by applied film thickness, the amount of sanding and type of wood. For the traditionalists the Ultimate Brightwork System offers excellent performance longevity: Use Awlspar M3131 to seal and provide some color to the bare wood. Apply 2-3 smooth coats. Leave to dry for 72 ours minimum at constant temperature of 77°F (25°C). In colder temperatures leave up to 7-10 days before finishing with Awlbrite Clear Urethane (available in full gloss or semi gloss finish). See the application guide and/or your Awlgrip representative for further choice in systems