To achieve a professional result from any varnish project, thorough preparation is critical. If applying on to a previously varnished surface, the condition of the existing coating and its compatibility with the new varnish product should thoroughly checked before commencing any preparatory or application work.
Before commencing preparatory work, ensure the area you are working in is adequately ventilated. Ensure you are wearing the correct PPE; we recommend safety glasses, goggles or visors, nitrile rubber gloves, overalls (ensuring skin is not exposed) and a solvent mask.
Check for areas of damage, separation or peeling, or any other indications that the existing coating is not firmly adhered to the substrate.
Clean with Special Thinner 216. Sand smooth with 280-320 grit sandpaper. Remove sanding dust by brushing or dusting. Wipe down thoroughly with Special Thinner 216 or Brushing Liquid 333 and allow to dry completely, to ensure any residual sanding dust is removed. (Note: Small imperfections may be spot primed and sanded down prior to full varnish application.) Continue at Step 6.
If previous varnish is cracking, peeling or showing signs of separation from the substrate this should be totally removed.
Clean with Special Thinner 216. Sand the surface smooth with 80-180 grit sandpaper to open the grain of the wood. Remove sanding dust by brushing or dusting. Wipe down thoroughly with Special Thinner 216 or Brushing Liquid 333 and allow to dry completely, to ensure any residual sanding dust is removed.
We recommend that the first coat of varnish applied is thinned up to 15%-20%. This will promote good penetration of the surface, and adhesion of subsequent coats. After the first coat has been applied, the surface will appear rough. This is a result of the exposed ends of grain absorbing the varnish and lifting. Sand smooth with a 220 grit sandpaper and apply a second coat thinned 10%-15%.
Apply 2-3 thinned coats of varnish following label recommendations. Alternatively, prime using Clear Wood Sealer; a clear polyurethane primer with excellent grain filling properties that will improve overall scheme durability and aesthetics.
Applying varnish with a brush is usually the best method, although roller application can be effective on large, flat surfaces. Brush out, using firm strokes along and then across the grain, holding the brush at 90º to the surface. Finally, ‘tip off’ by gently stroking surface with the brush at a 45º angle, following the grain. The brush you use should be used only for varnishing.
Always follow the system recommendations as specified on the label; this will indicate the minimum number of coats required and the sanding recommendations between coats. This information will vary depending on the product. To achieve long-lasting protection, you should plan to apply up to ten coats (depending on the system). As the number of coats increases, sanding between coats with a fine grit paper will increase the level of gloss and depth of luster.
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