Saturday, February 23, 2008

Quick lesson in chemistry -- shellac and lacquer

[Recycled post from October, 2006, which came up from someone's Google search.]

I was cleaning my windshield and came across a few particularly hard insect spots. As I applied the elbow juice I recalled reading about the lac bug, source of shellac, and it made perfect sense that an insect smached on the windshield could be a lot harder to remove than bird poop. We don't have lac bugs in North America, but I was inspired to look it up.

First of all shellac is not to be confused with lacquer. Shellac is that unique, now mostly obsolete product of the lac bug. Lacquer is a product of special trees, now enhanced by modern chemistry to become the versatile product that it has become. I'm glad to know that those lacquer keepsakes I got from Korea are not made of bug juice.

Here are the links to the two Wikipedia articles.

Shellac is a brittle or flaky secretion of the lac insect Coccus lacca, found in the forests of Assam and Thailand. Freed from wood it is called "seedlac." Once it was commonly believed that shellac was a resin obtained from the wings of a bug (order Hemiptera) found in India. In actuality, shellac was obtained from the secretion of the female bug, harvested from the bark of the trees where she deposits it to provide a sticky hold on the trunk. There is a risk that the harvesting process can scoop the bug up along with the secretion, leading to its death. The natural coloration of lac residue is greatly influenced by the sap consumed by the lac insect and the season of the harvest. Generally in the trade of seedlac there are two distinct colors; the orange Bysacki and the blonde Kushmi.

More than you ever needed to know at the link, including this:

Shellac is edible, and it was used as a glazing agent on pills and candies. When used for this purpose, it has the food additive E number E904. There were concerns that this coating is not vegetarian as it may contain crushed bugs.

Lacquer is not the same:

The earliest known lacquers were made in China, about 7000 B.C. These lacquers, made from the resin of the tree Rhus verniciflua, produce very hard, durable finishes that are both beautiful, and very resistant to damage by water, acid, alkali or abrasion. They do not, however, stand up well to ultraviolet light. The active ingredient of the resin is urushiol, a mixture of various phenols suspended in water, plus a few proteins.

Aagin, more than you need to know at the link...

Resume what you were doing.

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