Windex creates white spots in finish. What now?- Question of the week

February 6, 2007 | Filed Under Blog, Question of the Week 

This week’s question comes from Larry. He writes, “I have a question about a damaged finish on antique furniture. My wife’s cousin was cleaning her house and her 3 year old daughter was “helping.” Isabel, the helpful little youngster, sprayed Windex on a number of her mother’s antiques. The Windex, as I’m told, left white spots on the finish where it was sprayed. Being the only woodworker in the family I was solicited for advice. I know that ammonia based products can be used to clean shellac off of brushes and such, so my initial thought was that the furniture was finished with shellac. But, I’m not sure how ammonia affects other finishes such as lacquer and oils. I wouldn’t think that it would damage poly, but I’m 100% sure about that either. Are you familiar with this type of damage? If so, is there an easy/quick fix or does the finish need to be stripped? I’d appreciate any information you could give. Thanks a bunch. Love the web site and videos. They are quit helpful and informative.”

Here is my response:

“Hey Larry. Windex really isn’t good for any finish. Poly would certainly resist damage for much longer than shellac and lacquer, but I still wouldn’t recommend it for cleaning anything made of wood. If the finish is lacquer, the white spots could simply be from the water in the Windex solution. Water will create a hazy white spot of moisture that gets trapped below the surface. So, there are a few things you can do. Worst case scenario is refinish. The simplest thing to try would be to spray the surface with lacquer thinner. A good heavy coat will reactivate the lacquer and might allow the moisture to escape. Do you have the means to spray lacquer thinner? Another thing to try would be to spray a new coat of lacquer on the surface. You can use a can of Deft for this if you like. This also will redissolve the top layer of lacquer and might get rid of the white spots. Now there are also a few products on the market that claim to get rid of white spots but I dont have much experience with them. In fact, I was just at Lowes yesterday and they sell a pre-moistened rag (probably some sort of oil), that you can wipe over the spots to get rid of them. For $5, its probably worth a shot. I have also heard of a weird trick using mayonnaise. Since mayo is pretty much oil, you can put it on the surface so that the oil soaks through the finish and displaces the moisture. But who knows if it actually works. And to be honest, I would envision you replacing your water stain with a more unsightly oil stain.

Now all of that was based on the finish being lacquer. If the finish is shellac, you could try all the same things using denatured alcohol and shellac in a spray can.

If the finish is an oil, you can try a light sanding and reapply another coat of an oil-based finish.

I would definitely recommend testing the finish in an inconspicuous area to determine what the finish is. Just remember that lacquer thinner dissolves lacquer and alcohol dissolves shellac. And nothing dissolves poly. Just use a rag and those chemicals to determine what finish you are working with.

I would also like to mention a very important note. When dealing with antiques, you can severely diminish their value by refinishing improperly. If this is a valuable antique, I absolutely recommend having it looked at by a professional who has experience with old, valuable furniture. When it comes to these antique pieces, you are looking for antique restoration, not just a simple “refinishing”. Hope that helps Larry.”

Anyone else have some good suggestions for Larry??

Comments

5 Responses to “Windex creates white spots in finish. What now?- Question of the week”

  1. Larry on February 6th, 2007 11:39 am

    Thanks for the help Marc. I’ll let you know what works.

    Larry

  2. Dick Cain on February 6th, 2007 3:30 pm

    The same thing happened to me quite a few years ago. I made some candle holders out of some 3″ diameter Birch disks, & set them on our Duncan Phyfe dining room table. After sitting overnight, there were 20, 3″ diameter white spots on the table. I didn’t know what to do, so while hesitating for a short time they went away by themselves.
    So possibly in order to rush things along, maybe try a hair dryer on low heat.

  3. thewoodwhisperer on February 6th, 2007 10:03 pm

    A suggestion for Larry (submitted by Doug).
    A couple of years ago, my mother damaged her antique dinning table. She forgot to blow-out the candles on her center piece after a dinner party. Forty-five minutes later she returned to the Dinning room to find the candles had burned down low enough to light the center piece ablaze. In a panic, she poured a big pot of water over it, leaving a very nasty mess in the middle of the table. After the center piece and water was cleared away, she was left with a big white circle in the middle of the table. I was able to remove the white stains by using ground pumice stone, same as you would to rub out a finish. I’ve found that if the finished isnt damaged all the way thru its layers the ground pumice stone will take the stain out. Then just wax and buff the surface again. Experience with ground pumice stone helps, i use a small amount of distilled water as a lubricant. Hope this helps.

  4. Alex Blate on April 12th, 2007 8:39 am

    Marc:

    Thanks for the excellent content! I really appreciate your no-nonsense perspective on woodworking. I’m an engineer by day and a decidedly amateur/hobbyist woodworker by night/weekend; lacking the freedom to apprentice or train with a master, learning from articulate and down-to-earth experts like yourself is a tremendous asset.

    Now, to my comment… Real mayonnaise, as you say, is mostly composed of oil; if oil were the only thing you needed to remove the white rings, then the “folk remedy” would probably be to just apply vegetable oil to the stain. So unless Helman’s or Miracle Whip have started giving woodworking advise, there is something deeper going on. :)

    Let’s look at what else is in Mayo… Real Mayo contains vegetable oil, eggs (mostly yolks), and an acid, such as lemon juice. It may also contain flavor enhancers such as salt and commercial products will contain some preservatives. Some products that claim to be Mayo are really just fancy industrial chemical concoctions, so who knows what’s in them.

    Now, eggs, particularly the yolks, are powerful emulsifiers. This means, as you know, that they contain molecules which are capable of bonding to both water and oils. Soap is another emulsifier, but doesn’t taste nearly as good :) Compared to soap, the lecithin in yolks is much a weaker emulsifier, but it does the job.

    I would speculate that real mayonnaise, applied to a water stain, would be able to “cross” or penetrate the lacquer and absorb the water; subsequent cleaning with furniture oil would probably wipe any mayo residue away. It makes sense to me that it might work, though I haven’t had occasion to try it.

    One point is that you would have to use a “real” mayo — one which contains eggs, oil, and not much else. Many products in the supermarket are not true mayo. You could also make your own; Joy of Cooking’s recipe is quite good. If you’ve never had fresh, home-made mayo on your favorite sandwich, you haven’t truly lived. Just remember that its shelf life will be short, so keep it cold until use and dispose of any unused portion after a few days.

    Another advantage of home-made mayo is that you know that it hasn’t been pasteurized, which, AFAIK, would reduce the lecithin’s emulsifying juju.

    :)

    Alex

  5. thewoodwhisperer on April 12th, 2007 8:47 am

    Hey Alex. Thanks for all that helpful info. Guess I should tell you my other favorite way to spend my time: watching Food Network. :)

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