Hand Tools Archive

Subject:
Re: Hand finishing water-based poly.

Derek Cohen (in Perth, Australia)
Some of those milky white finishes are pretty much clear, though I prefer to amber them with a little dye because sometimes they come off as blue.

Nice process there Derek. Do you know something about the weather that we don't relative to making cabinet doors with waterproof glue?

Have you ever tried the brush LV sells for water based poly. I bought one, but it is so expensive I am still waiting for the perfect project.

Can't you cut that poly so it doesn't dry so fast. If it is sprayed presumably there is a reducer?

Thanks Tom.

No, I have not used the brushes from LV. The reviews of brushing made it clear that one of the issues with doing so was air temperature - higher temps made the poly dry faster, and here I am in Perth summer! It just wasn't looking good.

There are reducers available for spraying. This was not going to be an option.

Jim Waldron on SMC posted a really interesting reply, which I think will interest you as well. He called the method "tipping" ....

"You have found a technique that is common in the boat building and maintenance community but seems largely unknown to woodworkers: apply and tip/bush and tip/roll and tip and sometimes (but very very rarely) spray and tip.

The gist of the technique is to apply by whatever method is best for you, followed IMMEDIATELY by tipping. Tipping is to lightly brush over the surface with a dry brush, either a fine bristle brush or a foam brush. By lightly, the brushing is only enough to level any brush marks/roller pimples/spray orange peel and NOT A BIT MORE. Even the full weight of the dry brush may be too much pressure, so a very light touch indeed is required.

For an extremely fast drying medium like the aqueous polyurethanes, a bit more is required, since the coating is too fast to permit the customary tipping action. On the other hand, the stuff doesn't fully cure for several days and remains fairly soft for a short time. The (almost equivalent) prompt rubdown with a non-abrasive non-woven pad (Scotchbrite white or equivalent) will do much the same job, with one exception: there will be less gloss in the finished coating. Since very high gloss is rarely wanted by furniture makers and cabinet makers, in the end it comes out just fine. After about a week the polyurethane will be fully hard and the Scotchbrite white won't do anything more than dust off the surface.

If you ever truly want a coating with no color, you can use the polyurethane without the shellac sealer, rub the raised grain down after about half and hour (or more) with very fine paper (say 320 grit) or a fine Scotchbrite pad and go ahead with second coat with no more grain raising. In this case, I - like everyone else - prefer the tone added by the shellac. But since you started looking for no color, I thought I'd mention it. (Sort of a "be careful what you ask for moment?")"

Regards from Perth

Derek

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