Gerstner: Remelting nastry finish that turned black

Is it varnish and/or shellac that turns black with age?

I'm not interested in restoring it but need to do something about the finish.

Scraping it with razor or carbide removes a good bit of it.

But need to remelt it.

Formby's?

MrCreosote said:

Is it varnish and/or shellac that turns black with age?

I'm not interested in restoring it but need to do something about the finish.

Scraping it with razor or carbide removes a good bit of it.

But need to remelt it.

Formby's?

Click to expand...

Is it the original finish that turned black or it just dirty and needs a good cleaning?

It may or may not be possible to “re-melt” it depending on what it is and it’s probably not worth the trouble it would take.


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MrCreosote said:

Is it varnish and/or shellac that turns black with age?

I'm not interested in restoring it but need to do something about the finish.

Scraping it with razor or carbide removes a good bit of it.

But need to remelt it.

Formby's?

Click to expand...

But of course you need to do "something about", such finishes.

Industrial environments it may have served in are not always pleasant places. Years of wipe-down with the wrong "stuff" can take a toll. Most shellacs and varnishes are subject to being penetrated by unpleasant intruders. Either tribe may darken.

If the wood under them blackens, that is often a caustic or an acid at work rather than microbial breakdown. Moisture content thing.

Select the new finish based on what YOUR environment will see. Urethanes and lacquers are fast, gloss or "eggshell". Some among us don't much like them, prefer an oil finish.

Or even metal boxes, any fine woods (and Gerstner isn't, really..) exiled to the residence, not the shop.

Your shop. Your rules.

Mr Creosote,

Years ago I had an oak dresser that had turned black with age. I used 0000 steel wool and a paint / varnish remover to loosen and then wiped with a rough cloth. Looked like hand rubbed finish.

Formbys would work, or just look at the ingredients and buy a pint or quart of the most aggressive solvent.

I like hand applied Tung Oil for finishing bare wood. I'm a bowl turner and use that on them.

Paul

paul39 said:

Mr Creosote,

Years ago I had an oak dresser that had turned black with age. I used 0000 steel wool and a paint / varnish remover to loosen and then wiped with a rough cloth. Looked like hand rubbed finish.

Formbys would work, or just look at the ingredients and buy a pint or quart of the most aggressive solvent.

I like hand applied Tung Oil for finishing bare wood. I'm a bowl turner and use that on them.

Paul

Click to expand...

Tung oil is awesome. And also likes spontaneously combustion to wake you up in the middle of the night. You hope you wake up.

Stradbash said:

Is it the original finish that turned black or it just dirty and needs a good cleaning?

It may or may not be possible to “re-melt” it depending on what it is and it’s probably not worth the trouble it would take.


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Click to expand...

The "black stuff" appears to be the original finish - it definitely is not dirt.

Since this box is FUBAR as far as preserving the finish - they appear to have sanded it down on top - I tried various solvents to see what remelted the finish. Scraping the black stuff until I an see the wood grain emerge and then melt seems to be a good compromise. I didn't have any lacquer thinner handy but carb cleaner seemed to do the job but was too volatile and dried too soon - but there was gloss in places that looked good. So I'm close.

Let me step back and state my objective: this box was out in my partially enclosed carport along with other tool boxes, etc. where I work on projects and don't care about keeping stuff clean. However I want to bring this into my home and put clean electronic repair tools in it. Very clan stuff. The finish is just too nasty so I need to do something. To what extent, I will not remove any of the hardware to do this job. I'm looking to spend 1-2 hours on it.

SECOND biggest worry is the drawer felts since they have metal chips embedded in them. That is a real No-No. I was thinking of replacing the felts but then realized there were sides to do on top. Although I have the felt already, can't afford to spend the time right now.

Pulled most chips out with shipping tape, then soaked and brushed with Super Clean Purple degreaser, sprayed off in sink, let dry and then hand picked remaining chips out. MAYBE I might pull the bottoms out and replace and do the sides and tops later???

MrCreosote said:

The "black stuff" appears to be the original finish - it definitely is not dirt.

Since this box is FUBAR as far as preserving the finish - they appear to have sanded it down on top - I tried various solvents to see what remelted the finish. Scraping the black stuff until I an see the wood grain emerge and then melt seems to be a good compromise. I didn't have any lacquer thinner handy but carb cleaner seemed to do the job but was too volatile and dried too soon - but there was gloss in places that looked good. So I'm close.

Let me step back and state my objective: this box was out in my partially enclosed carport along with other tool boxes, etc. where I work on projects and don't care about keeping stuff clean. However I want to bring this into my home and put clean electronic repair tools in it. Very clan stuff. The finish is just too nasty so I need to do something. To what extent, I will not remove any of the hardware to do this job. I'm looking to spend 1-2 hours on it.

SECOND biggest worry is the drawer felts since they have metal chips embedded in them. That is a real No-No. I was thinking of replacing the felts but then realized there were sides to do on top. Although I have the felt already, can't afford to spend the time right now.

Pulled most chips out with shipping tape, then soaked and brushed with Super Clean Purple degreaser, sprayed off in sink, let dry and then hand picked remaining chips out. MAYBE I might pull the bottoms out and replace and do the sides and tops later???

Click to expand...

Everything you have done has been wasted monkey-motion the hardest and least productive way.

A woodworker doesn't FEAR the box nor try to "melt" dead finishes.

The hardware DOES come OFF, the old finish soon follows. ALL of it. The grubby old felt comes OUT.
You don't PICK at it with tweezers nor cello-tape! It isn't your face nor your ass, dammit!



Minor repairs now revealed as needed to corners and drawer slides are effected.

A new finish goes on, refurb or NEW hardware goes on (it is still common), new felts go IN, and soon DONE and good for another half a century, according to careful use. Or not so much.

It is FASTER. less effort, and produces far better results to do it the right way.

That's why we call it "the right way".

"Melting" and smearing about with brake cleaner?

Not only wrong. Not only nasty to deal with at all.

That s**t is expensive!

To answer your first question... I've never seen a varnish or shellac that will turn black with age, though they certainly look that way if they get alligatored or have some other textural failure and there is a lot of dirt on them and maybe even some subsequent finish applied. Many old finishes can be "re-melted" and leveled but the process for discovering what solvent will do that and the methods involved will consume far more time than you wish to spend on this and in the end it's not worth if for something of low historical significance. AS long as the hardware is readily removable I agree that it will be vastly more efficient to remove it and then the original finish. If you happen on the right solvent it might be that you can remove most of it and leave enough to have a good foundation for a new finish, but I'd be a little concerned about compatibility. I'm a bit puzzled though since you say the original finish is black. If that's so, and it's not just dirt on top of the finish, than it seems like you'd want to remove all of it anyway. It may be a nuisance to remove the hardware, but it will make cleaning it and the finishing work easier. As to what to put on the wood after you get it to where you want it, that's a tough call to make from afar as you should probably use what suits you and you're comfortable with. Spray "Deft" is easy to use, dries quickly and is efficient, but it's generally not my finish of choice as I prefer to see more character from the wood than that product affords.
It really does not matter what the original finish is at this point, but an aside, and I fully expect to get some objection to this, old shellac coatings cannot be readily re-disolved.
As for the felt, do what you're comfortable with. I'm surprised that the old didn't significantly loosen with your efforts to clean it using water etc as it's often glued in with hide glue. It might have been though and then treated, either intentionally or accidentally, to render it insoluble with water.
Enjoy and good luck with the project!

You didn’t mention if you tried denatured alcohol. If it’s old it might be shellac and the alcohol will “ remelt” the finish easily. Surprisingly, many of the other solvents don’t do much to real shellac.
MILO

MILO74 said:

You didn’t mention if you tried denatured alcohol. If it’s old it might be shellac and the alcohol will “ remelt” the finish easily. Surprisingly, many of the other solvents don’t do much to real shellac.
MILO

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If it's old, you'll probably not know what it is unless the odor gives it away. All that really matters it what will dissolve it or remove it. One of the best and cheapest things I've found for some old crappy finishes is household ammonia. It will however alter the color of some woods.

I did a drawer front scraping and then used some carb cleaner and it melted it nicely, but CC is too volatile - so there is a solvent that will remelt. I even got that golden finish that actually matches a place where you can see the original finish.

Alcohol did nothing. I have some expensive auto body lacquer thinner and reducer I didn't try. I'm out of acetone and xylene - need to restock.

I think Formby's would work but my purpose is FUNCTIONAL, not Restorative. And I have a variety of solvents that I should use up rather than buying another one.

The latches work so they are not coming off.

The felt is held in with hide glue. I have lots of nice felt in lots of colors but even in green it would be hideous to just do the bottoms which are the problem due to chip contamination.

Regarding the finish turning black: about 4" of the front panel was left and it turned nasty black. At first I thought it had caught on fire and was burnt!

OH SNAP! There are chips in the drawers. Maybe this box was repeatedly spattered with coolant, cutting oil, etc. which accounts for the black, gummy "finish."

Front Panel Also Swollen:

The middle vertical side pieces of the front panel swelled making it too wide to close and lock. You can see the expansion at the t&g joints along the sides. The panel is also too tall. Swollen I guess. I tried to "push them back" with a furniture clamp but they wouldn't budge and I didn't want to use excessive clamping force.

Was it rained on? In garage with leaky roof?

This is a very sad puppy.

Most likely shellac since that dries the quickest. Wash it with distilled water and soap. use scraper and steel wool if needed. Allow it to dry it completley then repeat the cleaning with alcohol. Finally brush it with pure alcohol. Let dry a few minutes and brush some fresh shellac over it if too much was washed off.
Bill D.
PS: lacquer is unlikely if you can see through the finish and see woodgrain. If it looks like gloss plastic then it is probably lacquer.

Here's a thread about a tool box I freshened up.
Have to scroll down a bit to see the after pictures.
The short version is boiled linseed oil and 4 aught steel wool.

https://www.practicalmachinist.com/vb/antique-machinery-and-history/old-tool-chest-216822/

Scruffy887 said:

Tung oil is awesome. And also likes spontaneously combustion to wake you up in the middle of the night. You hope you wake up.

Click to expand...

Put a rag out in the sun with Formby's finish on it. It did ignite.

So take it inside and let it acclimate to interior humidity rather than using clamps to take out the 'swelling'. That trick never works.

Put cardboard or plastic on the drawer bottoms for now.

You can use small carbide-blade cabinet scrapers to get rid of the existing finish in short order, and leave a surface clean enough to oil right away... once the wood has dried some.

Goal is to not mess things up so much that it interferes with the actual restoration to come, when time permits.

While the spontaneous combustion warnings for various chemical cocktails are completely legit, they are for rags or application pads, etc. not necessarily the finish as applied to the surface. So your chest is not going to explode into a ball of flame in the middle of the night, unless you wad up the finish-soaked rag and stuff it in one of the drawers... Lay out rags outside on concrete, out of the sun, until they dry. Then either dispose of in a fireproof trashcan or just skip ahead and burn 'em on the concrete where they sit. Or, dispose of as recommended by the finish mfg.

Butyl cellosolve if you can find it. It is a retardant for lacquer. Used to deal in antiques and used it to melt an alligatored finish and then let it re-harden. Watch out though, it really evaporates Extremely slowly. Try it out on something.

I think easiest way would be remove hardware sand it and refinish with your favorite finish (rub on would be quick and easy) . No need to over complicate. I’ve never heard of refinishing via melting, possibly for good reason? If a scrapper razor works and just pops the dry finish right off I would do that prior to sanding to keep the sand paper from gunking up as quickly.

After reading what you have done to that box, my best advice is stop now and take it to someone with experience in refinishing wood, and hope they can save it.

I will not remove any of the hardware to do this job. I'm looking to spend 1-2 hours on it.

FUGETABOUTIT!...........Bob

indianamoon said:

Butyl cellosolve if you can find it. It is a retardant for lacquer. Used to deal in antiques and used it to melt an alligatored finish and then let it re-harden. Watch out though, it really evaporates Extremely slowly. Try it out on something.

Click to expand...

So, would this work on my $500 baby grand that now has a dull brown finish with some checking? I'd just be shooting for 'smoother' and a fairly uniform color. Not looking for mirror anything, and don't much care about seeing the grain.