Woodworker's Journal 2009-33-6, страница 74
Finishing Hotline Getting to the Final Finish By Michael Dresdner ABOUT MICHAEL DRESDNER Michael Dresdner is a nationally known finishing expert and the author of The New Wood Finishing Book from Taunton Press. When not writing about woodworking, Ite is an active community theater Michael Responds: Your best bet is to sand the finish just enough to get it smooth and remove the ridges, then add another coat, but a smooth one. To sand, use 400-grit paper and be very careful around any sharp edges. If you choose a water-based finish apply it with very soft, nylon-bristle brushes or, even better, with paint pads — those rectangular, flat applicators with short white fibers on a blue or green foam backing. Apply the finish as thin as possible. Oil-based varnishes and polyurethanes should be thinned at least 15% and perhaps more, then applied with a high quality varnish brush (as opposed to a paintbrush) made with the softest bristles you can find. I like ox hair, but I'll work with an ox hair China blend when I must. The fiber bundles on varnish brushes taper from the ferrule to the tip. Paintbrushes cut off abruptly and arc the same thickness at the base and tip of the bristle bundle. Use the same soft brushes for lacquer or shellac. Water-based and oil-based polyurethane, shellac and lacquer are also offered in aerosol cans. If your skill with a brush or paint pad is not up to snuff, use an aerosol to apply the last coat. After the finish cures thoroughly, consider rubbing it out, a process we covered in depth in our December 2008 issue, Volume 32 Number 5. Contact us by writing to "Finishing Hotline," Woodworker's Journal, 4365 Willow Drive, Medina, MN 55340, by faxing us at(763)478-8396 or by emailing us at: finishing@woodworkersjournal.com Please include your home address, phone number and email address (if you have one) with your question. Pure tung oil can promote mildew growth. For exterior use, choose an oil-based spar varnish or polyurethane. will even work outside. As for recoating oiled wood, just scrub the surface with mineral spirits on nylon abrasive pads, a process that will both clean and lightly abrade the surface, then recoat with an oil-based finish. For outdoor pieces, use oil-based exterior polyurethane, spar urethane or spar varnish, all of which will go over oiled wood without any problems. I have just completed a cherry Shaker clock from your magazine's instructions. I am a capable woodworker, but my finishing skills leave something to be desired. The clock itself looks great, but the finish is dull and not at all smooth. I followed your finishing suggestions, but I just can't get any shine — the finish looks dark and dead. I can feel slight ridges as if I used a bad brush on cheap painl. I don't really want to sand everything off and start over. Is there some next step I can take that will help? Jack Im vallet Daphne, Alabama \ I am a novice wood-worker and do my finishing with tung oil. I'm currently finishing a table for a friend that will be used in a screened porch in the Southeast. I thought that linseed oil might work better than tung oil here, but I have been told that it may grow mold. Do I have to redo all my work with polyurethane, and if so, can I sand the tung oil and then add poly over it? James M. Ingraham Greensboro, North Carolina Michael Responds: Either pure boiled linseed oil or pure tung oil will work fine for interior pieces. However, I'd avoid either, and especially linseed oil, on exterior work, since nut oils tend to be natural foods for mildew and can promote mildew growth. You should be aware that while almost all linseed oil sold is either pure raw or boiled oil, many things called tung oil arc actually tung oil finish and not pure tung oil. You must read the label carefully. Some tung oil finishes |
