Which of the following stains is most likely to cause blotchy finishes?

Water-based stains are most likely to cause blotchy finishes due to the way they are absorbed by wood. Different woods have varying densities and porosities, which can lead to uneven absorption of the stain. For instance, softwoods and hardwoods can absorb water-based stains differently, causing some areas to become darker while others remain lighter. This uneven penetration can result in a blotchy appearance.

In contrast, oil-based stains generally flow more evenly into the wood grain, allowing for a more uniform finish. Gel stains are designed to sit on the surface due to their thicker consistency, which helps minimize blotchiness especially when applied to porous woods. Alcohol-based stains tend to evaporate quickly, leaving less time for uneven absorption to occur, thus also reducing the likelihood of blotchy finishes.

Understanding the characteristics of each type of stain helps in selecting the appropriate one based on the type of wood being used and the desired finish outcome.