What is the typical cause of blotchy finishes in woodworking?

Blotchy finishes in woodworking are commonly caused by uneven absorption and distribution of grain in the wood. Different areas of wood can have varying densities and grain structures, which affects how they absorb stains and finishes. When a stain is applied to wood, it penetrates more deeply in some areas and less in others, leading to an inconsistent appearance, often described as blotchy.

This issue is particularly pronounced in open-grained woods or those with a lot of variation in grain pattern, such as pine or cherry. When the finish is applied, the contrast between the denser and less dense areas becomes apparent, resulting in a lack of uniformity in color.

Other factors, such as uneven application of stains or finishes, and uneven preparation of surfaces, can contribute to an inconsistent finish but are not the primary cause of blotchiness. Similarly, uneven sealer coats can impact the final appearance but again do not directly cause the blotchiness that arises specifically from the wood grain's reaction to the finish. Thus, the correct answer relates directly to the inherent properties of the wood itself and how it interacts with finishes.