What finish am I removing?

[Anthony Whitesell]

A few years back I purchased a pair of night stands at auction for good money. Solid wood construction, possibly local shop made (ie., not Ikea nor big furniture store). There were/are some stains on the tops. I was told to use DNA and steel wool to remove the old finish. I soak a blue shop towel in DNA and then let sit on the area for a while, when I lift the towel, the finish is a softened gooey mess. I then loosen and remove the goo using 0000 steel wool in DNA and wipe away the finish/DNA slurry.

It occurred to me that I don't actually know what I am removing. I don't think it is shellac. It makes a brown colored slurry and if not wiped thoroughly a tan powder colored reside when dry. Any idea what I am removing?

[Bill Neely]

Probably multiple coats of shellac, I don't know of any other finish that DNA will dissolve.

[John McClanahan]

Shellac would be my guess, too.

John

[Anthony Whitesell]

I would also say shellac, except:

(1) it seems to remove completely. I have not been able to completely remove shellac just massively dilute the cut.
(2) and most obvious, when the alcohol evaporates and any remaining finish is allow to re-solidify it is an hardened opaque tan color. I have not seen shellac dry any way but transparent (colored but still see through)

[Steve Kohn]

From your description I would surmise you are dealing with a shellac finish that has a toner or dye of some sort in it. By removing some of the shellac you are effectively concentrating the remaining coloring agent making the color opaque.

I believe there are strippers out there for shellac, I'm just not knowledgeable as to what they are. Someone else may have a suggestion.

[John TenEyck]

If your objective is to remove the finish, don't diddle around with DNA, get some Kleanstrip Premium stripper. You don't need to know what finish it is; it will remove most any finish, quickly and completely. Follow the safety precautions.

John

[Steve Schoene]

The finish is likely shellac. If old enough, say 25 years. it could also be NC lacquer--over time the lacquer can deteriorate enough to become alcohol soluble. Still Shellac is most likely. If you are removing it as a brown goo, you are also removing the coloring agent, which could have been an added pigment, or dye, or just a dark variety of shellac. You would also be removing dirt accumulated over time. Alcohol will likely, with enough repetitions remove sufficient of the finish to remove the stains on the top. Likely with oxalic acid if these are the typical water stained dark spots. Stripper will also work, like John says, and perhaps take a little less time, but you need much more ventilation, a good pair of neoprene gloves and neoprene apron. But as you describe the DNA action in your case it appears to be working pretty well.