Finishing Touches - Applying a Natural Finish
Mother Nature provides a variety of methods for protecting wood...beginning with the bark on a tree. Bark insulates the live wood from decay, disease, insects, people who like to carve their initials into them and other pests.
Once the tree has been sawn into lumber and the lumber transformed into a piece of fine woodworking, there are a number of natural finishes that can be used to pick up the job of protection where the bark left off. Three of the most important finishes in this category are shellac, lacquer and varnish.
Each of these are made from saps, resins or chemicals that have been extracted from living plants - in some cases, the trees themselves. Like the bark, they form a protective coating on the outside of the wood. This coating is fairly hard and transparent, and can be built up through the application of successive coats.
Choosing a brush
Natural finishes can be applied using a number of different methods, but most of these methods have a single tool in common...the brush. The quality of this brush is extremely important. The better the brush, the better the final finish. Hog and badger bristle brushes are among the best. The bristles of these brushes are naturally split (flagged), allowing you to load-up more finish at one time and letting the finish flow more evenly onto the surface of the wood.
Proper care of these brushes is as important as their quality. Start by soaking your new brushes in a solvent (turpentine, alcohol or linseed oil) for a hour or so, then wrap them in paper and leave them wrapped for a day before using them. When you first dip your brush into the finish, spin it rapidly back-and-forth between the palms of your hands to dislodge any loose bristles (all new brushes have them). Dip it to only one-third of its bristle length and remove any excess by gently tapping it against the can rim. NEVER wipe the bristles across the rim, as this can loosen the bristles.
If you use your brushes often, keep them suspended in solvent. To clean and store them, slosh them in solvent, press out the excess with a smooth piece of wood and repeat. Wipe the brush dry, then wash thoroughly with a good detergent. Rinse, wrap the bristles in paper and hang the brush up, bristles down.
Shellac is manufactured by an insect, the lac bug, which sucks sap from a tree, then excretes a resin. This resin is later scraped from the trees and dissolved or cut in alcohol. Five pounds of shellac resin cut into gallon of alcohol is called a 5-pound cut. This cut is important; shellac should be thinned to at least a 3-pound cut before brushing. Buy shellac in small quantities, because once the resin is cut into the alcohol, it has a very short life -- usually only 4-6 months.