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Tip: When Finishes Craze from Body Sweat

crazing cross-linking finish the finishing store woodfinishing woodworking

All finishes craze—that is, develop small cracks—as they age, especially if they are exposed to a lot of sunlight. But there’s another type of crazing, and it can happen much faster. This is crazing caused by body sweat.

You commonly see crazing of this type around cabinet-door pulls and drawer handles, and on chair backs, arms and seats. The picture shown is a close-up from the crest rail of a chair.

This crazing is caused by the acids in body sweat slowly breaking down the finish. The finish softens and becomes dirty as dirt sticks to it. In severe cases like that shown, the finish separates up into small islands.

The finishes most prone to this type crazing are lacquer, shellac and water-based finish. Cross-linking finishes such as oil-based varnish and polyurethane, and two-part catalyzed finishes, are much more resistant.

If the crazing is superficial, you may be able to remove it by abrading with steel wool or an abrasive pad and still leave enough finish in good condition underneath to be functional. But usually, when the crazing has become bad enough to get you to do something about it, it is too late for this. The finish has to be stripped and replaced, which usually means stripping and refinishing the entire door, drawer or chair.



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