Michael Dresdner » water spots

Michael — Wed, 15 Sep 2010 14:00:25 +0000

Q: I am finishing alder with Daly’s Benite and CrystalFin, spraying with a Fuji gun and #55 needle. I have been using water damp cloths as tack rags. I am getting white spots in the dried finish. Most areas are fine, but some of the areas look like white overspray. The spots are down in the cured finish. I did not apply a sealer. Could this be an issue?
A: Probably not. The most common cause of white in waterbased coatings comes from applying it too heavily, or working in conditions where the water does not have time to evaporate before the finish starts to cure. Try spraying thinner coats, work on days when the humidity is low, or add a slowing solvent to the finish.

Blackwater?

Michael — Thu, 29 Apr 2010 14:00:22 +0000

Q: I have a solid teak dinning table that has a very bad and large dark water stain and I would like to get it out. How do I go about doing that?
A: Be aware that not all black water stains will come out. However, those that do usually respond to oxalic acid, but that only works on raw wood.
Start by removing all the finish with paint remover. You’ll find sanding the finish off is not always practical, since teak often has a penetrating oil in it. A strong paint remover will take it out, but you’d have to sand very far into the wood to sand it out. Once you are back to clean, raw wood, sand it lightly, then flood the entire surface of the table top, not just the area with the black stain, with a 10% solution of oxalic acid in warm water. Make sure it is very wet, but don’t leave puddles. Let the wood dry overnight, and if it comes out partially, but not completely, repeat. Once the stain is out and the wood is dry, remove the dried white oxalic acid residue with a damp cloth before finishing.

Water stains in black and white

Michael — Sat, 03 Oct 2009 21:24:49 +0000

Q: I made a cherry rocking chair for a client about 4 years ago. It has a Danish Oil finish. He recently called and told me that his wife had the chair setting next to her ironing board and now has water spots on the chair. He asked what to do to fix the water spots. I was thinking of telling him to go over the surface with 0000 steel wool and reapply Danish Oil to the surface. Would this be good advice, or is there a better way to save his chair?

A: It really depends on just how bad the water damage is, and more pointedly, what color the spots are. Black spots are in the wood, and reapplying finish will not remove them. To remove black spots, you almost always must remove the finish, then wash the sanded wood with oxalic acid. If you are lucky, that will remove the black stains and you can refinishing.

White water spots are typically on the surface or in the finish, and reapplication of Danish oil would, in many cases, solve that problem. Personally, I would use fine Scotchbrite® instead of steel wool, for a variety of reasons I’ve talked about previously. I apply wax with steel wool, but applying finish with it can create problems.