How to Troubleshoot a Polyurethane Finish
- 1). Look for a peeling finish. A peeling finish is most often caused by improper sanding between coats of polyurethane, or when a work surface is too dirty for the coat to stick. It can also happen if there is a bad chemical reaction between the polyurethane and any existing finish or wax residue. For the best result, properly sand and clean the surface before applying the polyurethane.
- 2). Examine the finish for cloudiness. Cloudiness occurs when polyurethane hasn't been properly mixed prior to use. All finishes need to be stirred by hand or with a drill-mounted paddle to mix the ingredients. If this isn't done, tint or dulling agents aren't evenly distributed through the product, and it can become cloudy or even have shiny and dull spots. Mix all polyurethane per manufacturer's instructions to avoid these problems.
- 3). Check the polyurethane finish for impurities. Impurities happen when tools and application materials aren't clean, and dirt or brush hairs find their way into the polyurethane. It can also come from the work environment itself, from dusty surfaces or foot traffic across flooring. Finally, some problems may be in the actual finish, so properly straining polyurethane before use is always recommended. Keeping tools and the work area clean can prevent these problems and leave you with a smooth and clean finished product.
- 4). Check to see if the finish has not dried completely. Occasionally, polyurethane doesn't dry properly. This is frequently caused by applying it too thickly, but it may also be caused by improper mixing or environmental conditions. Cold weather will naturally slow drying, and only time and adequate ventilation will help. More curing time is also necessary when the finish is too thick. Unfortunately, mixing problems may result in a complete refinishing because sometimes the polyurethane never dries.
- 5). Examine the polyurethane finish for bubbles. Bubbles in polyurethane occur for many reasons, but the most common reasons are rejection because of a problem with the material being coated, and not letting the polyurethane acclimate to the on-site temperature before opening and using it. Properly preparing the wood prior to finishing and letting the polyurethane sit at room temperature for 48 hours prior to use can prevent this problem.
