Urethane Application Tips
Urethane Application Tips
Read the Label Instructions!!!! Carefully!!
The first thing you are going to notice, especially if you choose to use a water based urethane, is that there are many things you can't do when you use a water urethane. For example, maybe you have had great success in the past sanding with steel wool. Those days are gone. Why? Because you leave very small pieces behind which will rust when you apply the urethane!
You may also find out that a previously applied finish has to be completely removed. This can be a bummer! Read the label application instructions carefully.
Surface Preparation is Everything
Your finial finish will be only a few thousandths of an inch thick when dry. Small imperfections will show through the finish. High gloss products magnify surface defects such as sanding imperfections, sanding scratches, bumps, hammer marks, etc. If you want a surface like glass, you must get it to a glass like finish before the finish is applied.
A water based urethane will absolutely raise the grain slightly. This is not a problem. Let the finish dry as recommended on the label. Then sand the finish lightly to knock off these high spots. When the second coat is applied, you should not have any grain problems whatsoever.
Clean, dry, dust-free surfaces are a must. Do not underestimate the importance of this. Remember, the urethane "sticks" to whatever is at the surface of the wood. If it is wax, dirt, dust, etc., don't be surprised when the urethane peels off in large sheets. I know this from experience. I urethaned the beautiful floors in a house once. Too bad I didn't remove the wax that the previous owner had applied!
Stir - Don't Shake
I always have to watch myself around urethanes. As soon as I pick up a can I want to shake it as I do with paint. Shaking urethanes introduces tiny bubbles within the product. Sometimes these bubbles will not disperse before the finish dries. If this happens you have big problems!
Sand Between Coats - Time Applications!
To get a mirror like finish you must lightly sand between coats. To get maximum adhesion between coats, it is important to apply the second, third, etc. coats as soon as the manufacturer says it is permissible. Why? Because often the previously applied coat will chemically and mechanically bond to the following coat. This can really make for a durable finish. Don't let days or weeks pass between coats.
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