OK, no matter how much woodworking I do, I still have questions about finishing. I’ve become pretty adept at applying polyurethane, but I’m wondering about techniques that might make it even better.
For my current project, I will be using wipe-on polyurethane, and I am wondering whether there is any benefit to polishing it. If so, can it be done with a dry pad? Or do I need to use a compound (and which compound would you recommend)?
Edited 6/16/2005 8:56 am ET by Matthew Schenker
Replies
Polyurethane varnish will never be any more glossy than it is right off the brush. Urethane is added to varnish to make it more scratch and heat resistant. "Finishing the finish" is scratching and the urethane is impossible to scratch consistant enough to produce a higher gloss.
At best polyurethane varnish can be "finished or rubbed" to a satin or semi-gloss luster. But, you must let it fully cure. Poly varnish can take 3-4 weeks to fully cure and you should not attempt any "rubbing" until then.
Polyurethane is just a broad description of the primary resin that is in a product. It comes in many forms and can be polished to a mirror like shine. I restore vintage motorcycles and spray a catalyzed polyurethane. This is a very hard surface and after blocking out, I use 3M Finesse It II with a low speed buffer. I can see my reflection clearly. Not many woodworking projects need this level of attention, other than pianos. Kind of messy, same with pumice and oil or rottenstone.
You can get a very nice finish on typical, wood finish polys by lightly sanding with 220 followed by 0000 steel wool and a coat of paste wax. While not as highly reflective as a compound polished surface, it will be baby bottom smooth and a cut above what you're used to. A finish is not done until it has been buffed out and waxed, in my opinion.
Beat it to fit / Paint it to match
>> I restore vintage motorcycles and spray a catalyzed polyurethane.I restore vintage motorcycles and spray a catalyzed polyurethane.Two part polyurethane finishes are an entirely different coating than a varnish made with urethane resin. The two part stuff is very nice on metal and we used to use it on fiberglass and aluminum boats. But, it is not a good product for wood. I will stand by my statement that a polyurethane varnish will never be any more glossy than it is off the brush. You can give it a somewhat smoother "feel" by rubbing it out, but it will not be as glossy. It depends what you want from your finish.Howie.........
A urethane is a chemical link, and a polyurethane is just something that has a lot of urethane links. They are all alike just as all fine furniture is alike, and could be described as "mortise and tenoned". Polyurethanes also have plenty of other structures and linkages in them. While many polyurethanes may be similar to one another, and many are not very glossy, (partly because less glossy finishes are popular) properties can vary a lot. Some conversion polyurethanes cure to a much stronger film with crosslinker added, but are just as glossy without it. HMG, the maker of Coma Berenice varnish, also says "K Type is a one part brush or spray applied polyurethane marine varnish available in a full range of gloss levels."
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