Polyurethane is today a very popular wood finish for home shop projects as well as professional woodworkers. Even though we at Obsessed Woodworking like shellac as an excellent wood finish, a subject we recently wrote about here, we also understand both the benefits of polyurethane and its ease of application.
When the wood has been well prepared, polyurethane will give your project a smooth finish, a hard film cover, great durability, and long-lasting protection for your project. By well-prepared, we mean:
We’ve written a few times about polyurethanes, most recently here. As noted in that piece, polyurethane comes in both water-based and oil-based versions, and well-known brands for polyurethane include Minwax and Varathane.
Minwax water-based polyurethane is a clear coat film finish – it does not penetrate the wood; it merely forms a protective film on the wood surface – as opposed to an oil finish that sinks into the wood. It is a plastic that is applied to wood surfaces as a liquid that, when fully dry, is a solid plastic sheet. It provides a water-proof barrier for the wood, protecting it from its enemy – moisture.
Varathane polyurethane will also give your wood a clear coat film finish that provides excellent protection from scratches and stains. It, too, is a good choice for your indoor projects like furniture, cabinets, and trim.
Oil-based polyurethane, while also protecting wood from moisture, dries and cures with a slightly amber tone to wood over time. This distinguishes it from water-based polyurethane.
Minwax Polyshades is an oil-based, one-step stain and polyurethane product that gives you wood stain color and polyurethane protection. Minwax suggests the best way to apply it is using the tip of a natural bristle brush in a thin coat with long, smooth strokes.
Sanding lightly in between coats with very fine grit sandpaper will remove any bubbles and start/stop marks. Be sure to follow the steps outlined earlier, wiping all dust from the surface before applying a second or third coat (to deepen the color) in the same way as the first.
One other “thane” to mention is spar urethane. It is for both interior and exterior use and is formulated to provide further protection to changing environmental conditions. The sun’s UV rays, like water, are wood’s enemy, and changing temperatures are the third on that enemy list.
Spar urethane is a more water-resistant finish than polyurethane and can be applied in higher moisture conditions. It also contains UV blockers to protect the wood from harmful sunshine.
As between the two, Varathane and Minwax, and while many consider Varathane to be more easily applied and with a faster drying time, Minwax is the less expensive option while still providing strong protection for your wood surface.
When originally developed, polyurethane had to be applied by brush. But as formulations evolved, it became possible to apply it either by spray or by wiping it on with a cloth. Additionally, mineral spirits can be mixed into polyurethane to thin it for a more forgiving coating – the mineral spirits will help break up any air bubbles in the coat before it dries.
A good ratio would be 3 parts polyurethane to 1 part mineral spirits. But, be sure to stir it slowly and softly, and never shake it so that you aren’t forcing additional air into it that will form bubbles.
In fact, you can now buy polyurethane that has been pre-thinned with mineral spirits. This Wipe-on Poly, as it is called, comes from Minwax and is ready for use right out of the can.
While Minwax suggests a heavy coat be applied, allowed to dry for 3 hours, and lightly sanded with a fine grit sandpaper, many other woodworkers suggest instead 3 thin coats for a smoother appearance. They also suggest not sanding the first coat, as you might sand through it; instead, allow the first coat to dry thoroughly, apply the second coat, and after it has dried completely, then lightly sand with a fine grit sandpaper.
When using PolyShades, is it necessary to sand between coats?
Minwax® Fast-Drying Polyurethane should be applied in a THIN layer using a high-quality natural or foam brush. Allow for a 4-6 hour drying period. *** Then, using fine sandpaper (220 grit), softly sand the whole surface to provide an equal finish and perfect adherence. Ensure that there is no dust remaining.
Is it necessary to coat the stain with polyurethane?
Is it necessary to apply a clear coat after staining to protect the staining? In addition to providing a rich, deep colour that shows the natural wood grain, staining also does not provide long-term protection. Water damage, scratches, and stains are all prevented by applying a polyurethane top coat to the wood.
Step 1 – Prepare the surface
To ensure proper adhesion, start by cleaning the surface with a piece of dry cloth.
Make sure that the wood is dry and free from any dirt and grime after the clean-up.
Then using a #220 fine-grade sandpaper, sand the surface gently in the direction of the grain to remove any grease or glue.
With a clean cloth wipe away all the sanding dust.
FAQ
Can you apply PolyShades with a cloth?
Is it OK to apply polyurethane with a rag?
Can you apply PolyShades with a roller?
Do you wipe off excess PolyShades?
