Q: When we finish wood, our first step is to apply a medium stain. Immediately, on some pieces of wood, we have some areas that seem to take more stain and will be darker than other areas. The wood appears blotchy. Can you help?
A: The problem you are experiencing is due to a special characteristic of wood called tension wood that only occurs in hardwoods. This special wood develops when the tree isn't growing straight, but is being pushed by external forces - by wind, another tree or even heavy branches. Where there is tension wood, there is more cellulose in the wood; cellulose is quite absorptive, so the stain will penetrate tension wood quite easily.
Further, cellulose fibers are weaker and do not machine well, so often there will be a little fine fuzzing in the tension wood areas. This fine fuzz will also absorb stain more easily than the rest of the wood. The result of either or both of these factors is a blotchy appearance. There are several steps toward eliminating the problem. First, make sure that you use sharp, fresh sandpaper. Fresh paper will have sharp crystals that will cut the fibers cleanly rather than rubbing and leaving fuzz. Second, avoid wet lumber, as wet fibers are more prone to fuzzing. Third, consider the use of a seal coat (wash coat or sizing) before staining to seal the surface and to prevent deep penetration of the stain so the stain will penetrate quite uniformly.
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