Replies

1. 
   chuckh | Oct 17, 2006 06:11am | #1

   Alan,

   Here are a few excerpts from a thread on this forum.  These are all tried & true solutions depending on the finish.  The first thing I would try is to simply wipe the area with a good furniture polish. 

    

   Wiping a white ring with an alcohol-moistened rag is definitely the standard procedure for dealing with water rings in a shellac finish. No doubt about that. But, the original poster here stated that his is an oil finish. Oil, not being alcohol soluable, won't be fazed by an alcohol rag. Shellac is alcohol soluable, which is why that procedure works fantastically on shellac finishes.

   Actually, the white ring that's visible isn't moisture that's been trapped. Rather it is the resins in the finish that have been knocked out of precipitation by the presence of moisture. The moisture itself is long gone shortly after the ring is caused, leaving one with nothing more than an unsightly white ring of resins out of precipitation. What the alcohol does on shellac is it redissolves the top layer of the shellac, allowing the resin to go back into proper balance in the finish. Ketones (MEK, Acetone, etc.) do the same thing for nitrocellulose and acrylic Lacquers. Those solvents work for those finishes precisely because those particular resins are readily dissolved by those specific solvents without incurring any damage to the resins.

   What's happening on a non-compatible resin, if wiping with an alchol-moistened rag removes the ring, is simply the friction of the rag itself rubbing away the small amount of resin that's out of the mix and causing the white ring. IOW, the same thing could be achieved with simply the rag, or the rag and any number of other substances that won't do a thing to dissolve the resin. That's a perfectly good solution to some water blush marks, even with shellac and lacquer. It all depends on where the water mark is at in the finish. If it's on the surface then any polishing action will remove it by simply wearing a minute layer of the finish away. For water marks that are deeper in the finish, the only solution... if any solution will work at all, is to use a solvent that will dissolve the finish without damaging it. That's why I mentioned in the earlier post that oil is not alcohol soluable.

   Frankly, I don't know of any solvent that will dissolve a cured oil finish without permanently damaging it. Wet sanding blemishes in a cured oil finish with a fresh oil finish of the same type is a perfectly acceptable and very widely used technique.

   always suggest something like mayonnaise first.  We were just trying to be the least invasive.

   Absolutely. That's the best approach. You'd make a great art conservator with that attitude. I'm serious. :-)

   BTW, I suspect what mayonaise is doing on the white rings is the vegetable oil in it is simply filling the uneven surface caused by the resin bits being out of precipitation. When they're like that on the surface, they function the same way that flatting agents do - they refract light on the surface to change the amount of light that's reflect back at any given point. They also change the manner in which you percieve the light that is reflected back. That's why the ring appears white even though there's not a stitch of white pigment there. You could wipe mayonaise over a dead flat finish and wipe the worst of it off and there would be a satin

2. 
   Gretchen | Oct 17, 2006 03:49pm | #2

   As with any thread on the internet, it is usually a matter of opinion.  I think the overwhelming opinion is that white rings are indeed due to trapped water moisture.

   The rubbing with denatured alcohol is the usual wisdom but it MUST be done very cautiously and "wispilly"--just passing it over the spot. And it can be done on other than a shellac finish.  I personally have never had the courage!

   I have put mayonnaise on the spot and covered with saran wrap to let sit. Believe it or not, this will work.

   The other thing I have used with success on quite bad white rings is Howard's Restor-a-Finish.

    

   Gretchen
3. 
   joinerswork | Oct 17, 2006 04:10pm | #3

   Alan,

   As with so much in life, "It depends."  If the white ring is paste wax that got wet, a gentle rub down with 0000 steel wool will likely do the trick.  You can use a little petroleum jelly as a lubricant. Try not to rub thru the finish film as you work in one area. 

   If it is shellac, the wipedown with alcohol might be just what the Dr. ordered.  I've had very good luck with this in the past.  Also, I've had occasions where the alcohol bubbled the shellac film as soon as it touched it.  WHOOOPSIE!  Try this on a hidden area first.

   I've had less success with the mayonaisse trick, but others have.  Some brands of "saran" wrap are very compatible with some brands of nitrocellulose lacquer, and will melt right into it over time, so keep an eye out for that as well.

   Good luck,

   Ray