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Expert's Corner — alcohol

The Exotic Vocabulary of French Polishing

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One of the difficulties with learning to do French polishing is overcoming the exotic vocabulary that continues to be used by some: “charge the rubber,” “fad in,” “spirit off,” etc. This vocabulary was created by English craftsmen 200 years ago, brought to the United States, and used in most instructions since. I’ve always thought it pretentious to use this vocabulary when there are perfectly good words everyone understands that can be substituted. Here’s the translation. “Rubber” was the name given to what we commonly call a pad, made by tightly wrapping a smooth, finely woven outer cloth such as a...

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TIP: Shellac Thinner

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The thinner and clear-up solvent you should use with shellac is denatured alcohol. This is ethanol, the same alcohol that is included in beer, wine and liquors. But it is made poisonous so it can be sold without liquor taxes. Sometimes you’ll see methanol (methyl alcohol) sold in paint stores. Methanol works fine for thinning shellac, but it is quite toxic if you are around it for a long time breathing the vapors. So it isn’t a good idea to use methanol unless you are working with a good exhaust. Isopropyl rubbing alcohol is no good for thinning shellac because...

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Finishing Tip by Bob Flexner: Testing for Shellac

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Finishing Tip by Bob Flexner: Testing for Shellac

Almost all furniture and woodwork finished between the 1820s and 1920s was finished with shellac. But if you want to test to be sure, here’s the way to do it. Put a little denatured alcohol on your finger and dab it onto an inconspicuous area of the finish, as shown in the accompanying picture. If the surface gets sticky or if the finish comes off on your finger, the finish is shellac. Shellac dissolves in alcohol, so you could use the alcohol to strip the finish if that is your intention, instead of using paint stripper.

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TIP: Stir Homemade Shellac

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TIP: Stir Homemade Shellac

Shellac is available in two forms: as a liquid in cans you buy at paint stores and home centers, and as flakes you buy from woodworking suppliers. The advantage of dissolving flakes (in denatured alcohol) is to ensure the shellac you use is fresh. The fresher the dissolved shellac the quicker it hardens and the more water-resistant the dried finish. Unfortunately, the sole remaining supplier of already-dissolved shellac no longer supplies a date of manufacture, so you have no idea how long the can has sat on a shelf or been stored in a box somewhere. When finishing important surfaces,...

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TIP: Dating furniture by the finish used

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TIP: Dating furniture by the finish used

Because different finishes have been used at different times, it’s often possible to date furniture simply by the finish on it. In the 18th century and earlier, makers used whatever finish they had available, usually wax or linseed oil. If the maker lived near a port city, alcohol- or turpentine-soluble resins may have been available. By the 1820s, transportation had improved and shellac flakes, along with other alcohol-soluble resins, became widely available. Alcohol evaporates rapidly so these finishes dry fast and don’t collect dust. As a result, shellac became the overwhelmingly dominant finish used on almost all furniture and woodwork...

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