Mark Chervenka: Shellac - the perfect sealer and finish for repurposing
inMarch 14, 2012 - 3:18pm
Without being obvious, one of the biggest expenses in many repurposing projects is often the final finish or seal coat. You might have little or no cost in your salvaged parts yet spend $20 to $30 or more finish or seal them.
Shellac, used for centuries by master artisans in a variety of trades, is a low cost alternative to expensive 21st century acrylic and urethane finishes and sealers specified in current how-to magazines, web sites and books.
Besides its low cost, about $13 per quart, shellac is amazingly fast drying. Right out of the can it is dry to the touch in about 10 minutes and can be recoated in 30 minutes. Thinned down, shellac can be made to dry so quickly it can be recoated in a matter of minutes. It sticks to virtually any surface—metal, wood, ceramics, glass, paper, plastics—whether they are rough, smooth, painted, rusty or anywhere in between. When dry, shellac is non-toxic and safe for use around children and pets.
Shellac has been made since the thirteenth century. The raw ingredient is an insect secretion on trees that grow in India. Dissolving the material in denatured alcohol produces the liquid form. Cabinetmakers buy shellac in flakes and add the alcohol themselves but for most do-it-yourselfers ready mixed shellac sold in cans is a better choice. You buy shellac in the paint departments of big box home centers and hardware stores as well as your neighborhood paint store.
Premixed shellac is available in clear and amber (Fig. 1). Use clear shellac to seal paper, photographic prints, books, record album covers, bare or finished wood and other objects where you want the original surface to be visible and unchanged. Amber shellac has an orange-yellow color which is perfect right out of the can for creating an “antique” or “distressed” look to an existing or new finish.
Both clear and amber shellac can be tinted with universal colorants, available at paint stores, or acrylic paints sold in the small bottles at craft stores. Colorants are intense and only a few drops will tint a relatively large volume of shellac; substantially more acrylic paint would be required to achieve the same tint. For lighter tones and pastels, use clear shellac as your tinting base. For darker tones, especially wood tones, add tints to amber shellac All tinted shellac, regardless of how it’s colored, must be stirred frequently to prevent the tinting agent from separating out.
For most purposes, shellac should be thinned before application. This speeds drying, prevents blotching and reduces brush marks. As a general rule, mix one part denatured alcohol to four parts shellac for general work; increase ratio to one part alcohol to one part shellac for fast drying seal coats. One to one mixtures dry almost instantly allowing repeated coats to be applied in rapid succession. Thin coats also permit a subtle blending of color and tone.
You apply can apply shellac with brush, rag or roller. Unlike brushes, rags don’t have to be cleaned and can be made of any fabric scraps that would otherwise go directly to the landfill. Apply in long smooth strokes on all materials; follow grain direction if working with wood. For smooth more formal finishes sand lightly between coats with 220 grit sandpaper. Clean up with denatured alcohol. Only store shellac in metal or glass containers. Before closing, wipe lids of cans and jars with alcohol to prevent lids sticking.
Shellac and denatured alcohol are both flammable. Carefully follow the manufacturer’s directions for safe use. Use only with adequate ventilation and safely dispose rags.
Photo 1: Ready mixed shellac is available in amber, left; and clear, center. Shellac is thinned and cleaned up with denatured alcohol, right.
Photo 2: Before and after views of a distressed finish created with shellac on picture frame molding, left. Shellac applied as a seal coat to the bottom half of a piece of cast iron, right.
By Mark Chervenka for Ruby Lane.