I avoid blcachcd shcllac bccausc it has less durability, a shorter shelf life, and less water resistance than any of the other types.
In its natural state, shcllac concains about 3% to 5% wax. This wax creates a more satiny finish and makes the shellac easier to sand. For most furniture and other items, natural shellac is fine.
But as a matter of habit, I always buy dewaxed shellac. Although it costs more, it's harder, clearer, glossier and more water resistant. It is the best choice for items that must endure water, such as kitchenware, table tops and chairs. It's also best for French polishing or for sealing under other finishes that may not tolerate wax contamination—especially water-based coatings.
You can buy any variety of shellac as flakes, mixing them with denatured alcohol for application.
You can mix shcllac to any "cut* that you like. The cut refers to the number of pounds of flakes per gallon of alcohol. I prefer to work with a 2-lb. cut, which flows niccly off a brush or rag, sprays well, and dries faster than a thicker consistency will.
To make a 2-lb. cut, you can weigh and measure out the relative proportions of flakes and alcohol for any amount you like, but I use a simpler method: Mark a line on a glass jar indicating the amount of shellac you want. Fill the jar halfway to the line with shcllac flakes, then pour in denatured alcohol to the line. Shake or stir the mixture frequently. Oncc it dissolves, usually overnight, it will be close to a 2-lb. cut. The nice thing about shcllac is that you can always add more alcohol or flakes later to thin or thicken the mixture. You really don't have to fuss with exact proportions. Use whatever consistency works for you.
To ensure its freshness, I mix just what I plan to use within a couple of months. As soon as alcohol is added to shellac, the mixture begins to change. The liquid starts taking longer to dry, forms a softer film and becomes more water sensitive.
You can also buy premixed shellac, which usually comes as a 3-» 4-, or 5-lb. cut. This means that 3» 4, or 5 lbs. of shellac flakes were added to a full gallon
Hand stretching. The shellac resin is melted down, then stretched into sheets before being broken into flakes.
of alcohol. To convert a 3-Ib. cut to a thinner 2-lb. cut, I add 5 ounces of denatured alcohol per pint of the premixed solution.
Although premixed shellac is convenient to use, it can cause problems if it's not fresh. Bccausc of this, most manufacturers print the date of manufacture on the bottom of the can to ensure freshness. Keeping it cold will prolong its life, but it is best to buy only what you will need within a few months and use it as soon as possible. Some formulations claim a shelf life of over a year.
Shcllac flakes can be damaged by light, moisture and metal containers, so store them in opaque plastic or glass in a cool placc. Avoid storing premixed shcl lac in metal containers as well since it will corrode them. (Premixed shellac comes in stainless steel- or epoxy-lined cans.) To prolong its shelf life, store mixed liquid shellac in the refrigerator or freezer in well-marked containers. (After all, you don't want the family using it for chicken broth.) The liquid shellac will thicken but it won't freeze, and it will thin out again when it warms up.
Shellac is usually brushed on, but you can also apply it with a rag or spray it. To brush it, use a soft, natural-bristle brush and work quickly. Don't try to rebrush; shellac dries too fast. Whenever possible, apply shellac when the temperature is cool. It will flow on more smoothly because the alcohol evaporates slowly. Wait at least two hours before recoating and only scuff sand if you need to level the finish. I sand with 220- or 320-grit paper. Clean brushes with a mixture of water and ammonia. Wiping shellac on is a great way to apply a very thin sealer coat. Make a pad from a clean cotton rag and dip it in your 2-lb. cut of shcllac. Flood a small area of the wood, then immediately wipe off the excess with another cotton rag.
Shellac is friendly to spray, but you need to apply more coats to get the same coverage you'd get by brushing it. Try using a 50-50 mix of 2- or 3-Ib. cut and alcohol. If you want more flow, add alcohol. If you want more body, mix in more flakes. Spray four coats at least one hour apart. A
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