Alcohol

Denatured Alcohol - DNA

In some countries DNA is called methylated spirits, or wood spirit, or denatured rectified spirits.

Ethanol - Ethyl Alcohol - is a great solvent, a clean burning fuel, and a key part of liquor. The latter use makes it a potential tax revenue source, but it you are just going to clean with it, or use it to dissolve shellac flakes, you certainly don't want to pay the very high liquor tax.

Methanol - Methyl Alcohol - is chemically very similar, but it is extremely poisonous, starting with blindness. Adding 5% methanol to ethanol doesn't interfere with it's other good properties, but makes it useless as a beverage - hence no liquor tax. Some jurisdictions (countries) require additives other than (or in addition to) methanol, such as ipecac to cause vomiting, or pyridine to make it smell bad, and/or methyl violet to give it a unique color.

I have seen DNA sold as non-streaking glass cleaner.

Mixing shellac. Full strength shellac is "3 pound cut" or three pounds of crystals in a gallon of Denatured Alcohol. Two pound cut is 2 pounds of crystals in a gallon of DNA and is sometimes sold pre-mixed as primer. Thin shellac, that you might use as a sealer, is a one pound cut. Since Alcohol absorbs water from the air, don't mix more than you will use in a few days. I have never heard of a woodworker mixing a full gallon - a few ounces is a lot. And be sure that you don't get the version of DNA that has pyridine to make it smell bad.

Cleaning dust during finishing: In the dark ages we bought tack rags that were sticky to pick up dust, but it left a trace of oil - a disaster with modern finishes. Therefore it is common to use a 50/50 mix of DNA and water, and spray a fine mist on a clean wiping cloth.

Isopropyl Alcohol

As Denatured Alcohol is becoming more expensive and highly regulated, are there alternatives? For assistance I contacted Jeff Weiss, owner and the chemist who developed the popular Target Coatings.

Isopropyl alcohol, sometimes called medical or rubbing alcohol, is much less toxic than denatured alcohol. Chemically is it still an alcohol, but is much different, and far less expensive. It cannot be used to make shellac. It cannot be used as a fuel in alcohol stoves or in chafing dishes used by catering services. But it is what medical people use to clean your arm before getting a shot, etc.

I have seen "Rubbing Alcohol" with as high as 95% isopropyl alcohol, but it is often diluted with water to 70% alcohol or less. Jeff confirmed that it could be used for cleaning finishes if you add water until you are at about 50% isopropyl alcohol. Once it is diluted to 50% alcohol, you will make the 50/50 mix of alcohol and water, so probably will have well over 50% water. Then use as before - I typically keep a spray bottle with the alcohol water mix, and mist a clean rag before I dust with it.

CAUTION: Lacquer Thinner is totally different than any alcohol. In fact, if you are testing what finish is on a piece being refinished, first wipe with alcohol (if the finish softens, it is shellac), then wipe with lacquer thinner (if the finish softens it is lacquer). If neither alcohol nor lacquer thinner hurt the finish, it is probably varnish. Home Depot web page is now selling containers labeled lacquer thinner that presumably contain denatured alcohol. I have no idea what is actually in the container from Home Depot, but I am not taking any chances.

Trivia

If you mix a half cup of alcohol with a half cup of water, you will end up with 4% less volume than you put in the mixture - 96% of a cup in this example. The molecules of alcohol and water fit together, so the volume of the mixture is less. If you had measured by weight, it would all be there.

Proof of alcohol is the percent of alcohol BY VOLUME, times 2. A beverage with 40% ethanol by volume is 80 proof. Absolutely pure alcohol (lab alcohol) is theoretically 200 proof, but it is so hygroscopic (absorbs moisture, such as from the air) that it is considered 195 proof. That factoid is only important in trivia arguments.

Good luck! Your comments and feedback are appreciated.

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