hey Paul...
glad to see ya stopped in... been wondering about ya buddy...
let's see if Keith Mealy can help ya out...
the PDF has pictures....
Every once in a while you’ll get a white spot on a finished surface. This is caused by moisture penetrating the finish and making it cloudy. As a finish ages, it gets more susceptible to such damage. Heat exacerbates the problem, whether it is from a tea cup or carry-out pizza box.
There are lots of approaches to fixing this and it can depend on the finish, the age of the damage, and the extent of the damage. Not all of them work all the time. Removal of white water rings brings the kooks out of the woods, each with their own secret method (just check Pinterest). Here are a few approaches that people suggest (and my opinions on them).
Oil the surface
Apply some mayonnaise or Vaseline and let it sit overnight. I can’t say that I’ve ever tried this because it is not always successful and as a professional, I can’t just smear some Hellman’s on their table, take a bit of a candy bar, and tell them to clean it in the morning. I need a positive result before I leave. Other people suggest vinegar and olive oil rubbed in. (I’ll save that for my French fries at the fair)
Heat
I am not so sure about this one.* You have to hit just the right heat level or you can do some severe damage. You can try to heat the area with a hair dryer.* A hair dryer might be fine, but a heat gun can easily blister a finish.** I also read an article once on dribbling on some denatured alcohol and setting it on fire.** Did trial on this once, blistered the finish.* And you might set your shop* or dining room on fire.
Another approach some suggest is putting down a cloth and ironing. Hmm. Heat can melt and finish and then you end up with a cloth impression and fibers locked in your finish. So pass on this one, IMHO.
Reamalgamate
Lacquer (often found on factory finished furniture) and shellac are best choices for this. Since re-introducing their solvent(s) melts the finish then it re-cures. I have used these successfully.
Touch up places sell aerosol cans “blush eliminator,” “no blush,” and “blush remover.” These are simply a slow drying lacquer thinner. It melts the finish and allows the moisture to escape while it re-cures. IF you don’t have the aerosol, you can spray some lacquer retarder (thinner) on the surface.
Another approach is to pad with a rag dampened in denatured alcohol. Just damp, not dripping. This is quite effective on shellac and will also work on aged lacquer.
Here is a vintage piece that I repaired after it sat in a leaking moving van under a mover's, blanket.* I wiped with a cloth dampened in DNA.* I also cleaned up a bit with padding lacquer. before and after
There is also a touch-up product called “Padding Lacquer”* this is normally shellac that has lacquer thinner (that contains alcohol) as its solvent.* Pad this on and it works similarly to the alcohol only approach and adds some more finish.
Howard’s Restor-a-Finish contains some alcohol and acetone and is in this category. Briwax’s solvent is toluene, and it works similarly.
Oily Abrasion
This is my go-to method usually. There are several manufacturers of treated cloths (usually called “White Ring Remover Cloth”) that you rub on the spot and it goes away. The cloths have a very fine abrasive and oil (sometimes tallow acid). Guardsman makes one usually sold in Bed Bath & Beyond and sometimes Lowe’s. There is a larger version that is made by Homak and Jasco (identical product, different color packaging). I’ve found these at various big boxes, but not consistently. Now I order a dozen or so at a time online. [These cloths can also be used as general purpose polishing cloths. They work well on brass, some people even use them to polish their trumpets]
If you don’t have these, some say you can use a light abrasive like rottenstone or cigarette ashes and some rubbing oil, toothpaste, or fine steel wool and oil.
Clean up the oil with Dawn and water or an emulsion furniture polish.
Abrasion may change the sheen, glossier for the stain removal cloths, and flatter for steel wool. You can apply more finish or simply rub the whole surface if you don’t mind. I’ll just spritz with the right sheen touch up lacquer on lacquered furniture.
Special Case: Oil Finishes
Oil finishes can get white spots because moisture penetrates the oil finish and raises the grain. Oils finishes have virtually no water excluding factor. The solution here is to lightly sand and reapply the finish. You can even wet-sand in the oil with a wet-or-dry sandpaper.
Here's another approach that I tried unsuccessfully to show when I did the TGIF. Just showed up on my feed.
He uses hand sanitizer (gelled alcohol) on 4 layers of shop towels, lay on top and let the fumes do the work. One minute at a time. So it's another approach on the "reamalgamate" method.
https://www.popularwoodworking.com/...-white-rings-haze-from-finishes-and-furniture
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