Sanding between coats of polyurethane is definitely a topic that sparks a lot of debate, and for good reason. The short answer is: yes, sanding between coats is generally recommended, but the specifics can depend on several factors.

The primary purpose of sanding between coats is to promote adhesion. Fresh polyurethane layers tend to bond better to a slightly roughened surface rather than a glossy, smooth one. That’s where those microscopic grooves come in-they give the new coat something to cling to, reducing the chances of peeling or uneven layering. But it’s crucial to use a very fine grit-usually 220 or finer-to avoid deep scratches that could mar the final finish.

Timing is equally important. Sanding should only be done once the previous coat is completely dry, typically after 24 hours, though this can vary based on product type and environmental conditions. Sand too soon, and you risk smearing or clogging the sandpaper with wet finish.

However, there are exceptions. Some newer water-based polyurethanes promote adhesion without sanding, while certain finishes like wiped-on oils or gel stains often don’t require it. If you’re aiming for a glass-like, ultra-smooth finish, you might want to sand very lightly or even skip it between some coats, but this tends to be the exception rather than the rule.

Ultimately, sanding between coats is about balancing patience with precision, ensuring each layer builds toward a flawless, durable finish. Skipping this step might save time upfront, but the long-term beauty and durability could suffer. So, sanding is usually the wise, professional choice.