Wood Surface Preparation & Its Impact on Finishing
By Phil Stevenson | Posted: 05/09/2013 3:46PM
Conestoga Wood Specialties Final whitewood sanding is the most important step in finishing for satisfactory results. Poor finish quality, rework, and missed expectations are in most cases a direct result of improper final whitewood sanding preparation.
There are three commonly used methods to prepare the surface of the wood as a final step before finishing: widebelt sanding, random orbit sanding and brush sanding.
Widebelt sanding to 220-240 grit sandpaper works well for flat panel work and where a linear scratch pattern with the grain of the wood is acceptable. Random orbit sanding is used as a final step to remove minor defects and provides a scratch pattern that is invisible after finish is applied. However, this method cannot sand in profiled areas and can be inconsistent when using manual hand orbiter sanders. Brush sanders use strips of abrasive and are backed by different types of brush media to force the abrasive strips into corners and recessed profiles of the substrate.
Of these three technologies, brush sanding has become one of the most viable technologies to become lean and improve profitability in finishing. While many companies still do a considerable amount of orbital and hand sanding, brush sanding, when set up properly, can eliminate most hand sanding labor. New brush sanding technologies can provide the following process benefits:
• Consistent breaking of sharp edges to eliminate sealer sand-through
• Consistent stain color and elimination of most blotchiness
• Consistency of finish color in day to day production
• Elimination of most fiber raise, a very important consideration with water base finishing
• Removal of drag marks and minor defects
• Opens the pores of the wood uniformly for even finish absorption
• May reduce volume of coatings consumed
From a lean perspective, brush sanders will reduce rework, lower sanding preparation labor, and lower material costs. In addition, correct brush sanding technology will return profitability on investment quicker than most any other investment in finishing. Most wood manufacturing shops with $7 million to $10 million in sales and up should see a return on the investment in less than one year, but not more than three years from purchase.
The benefits of finish quality cannot be overstated when using the right brush sanding procedure. The uniformity of stain colors, depth of finish, and the clarity of the finish will dramatically improve the visual perception of the product. Removing the human error factor from hand sanding operations also provides confidence in the consistent outcome of the final finish quality. In some situations, a color step may be eliminated to reduce the amount of the cost in the finish while still providing a high-end look.
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