The blade is the largest and most important part of a table tennis racket, and playing with a brand new one is unlike anything else. As a result, keeping a blade in like-new condition is a smart idea. Applying a sealer helps keep it in mint condition for an extended period. Some players question the need for sealer, but as time goes on, more agree it is smart in the long run. When you pull off rubbers to change them, unsealed wood can splinter even if you're careful. Blades undergo pulling and re-gluing often because most players change rubbers every six months. The sealer prevents excess wear and tear.
Polyurethane is the product of choice for sealing ping pong blades. It's a popular product readily available from any hardware store and is durable. The manufacturer's use instructions on the container will guide you in applying it – and take special care to use it in a well-ventilated area. It does have an odor that you don't want to breathe. Polyurethane isn't much thicker than water, which means you need to be careful to avoid drips. Set up an area where it's okay to drip as you're working. Therefore, don't use is without covering a table, the furniture nearby, and the floor underneath.
Preparing the blade to be sealed is crucial before you begin. As you'll read on the can, polyurethane adheres to clean surfaces. You also want your blade to look good, and sealing over dirt and scuffs is not going to be attractive. When it comes time to glue down a new rubber, you need a smooth surface, and it's another reason why prepping before sealing is vital. When applying the polyurethane, put on a generous amount and be neat in your work. A smooth, even coat of sealer across the blade's entire surface will produce the best results. If you apply it too thinly, it might not protect as well.
Keep in mind that light sanding will remove any excess sealer after it dries, so it's wise to go ahead and apply a heavy coat all over the blade. Always keep an eye on the edges as you are painting it on. They need to be thoroughly sealed as well. Do not seal the handle because it might become slippery while you are playing. The sealer's purpose is to protect the blade and especially the areas when you glue on and tear off rubbers. Sanding very lightly across the entire surface before gluing down the first rubber is a good idea. Rough it up a bit improves adhesion of the glue.
