Most of us know about dissolving steel wool in vinegar to make an ebonizing solution. Vinegar also works to dissolve or soften yellow glues. 

Some people can store knowledge and generalize bits of it to apply from one situation to another. Apparently, I'm not one.

Last week, I discovered that I'd glued a maple piece incorrectly. It was 3"X 8" and glued on the flat 8" surface. No sweat. Just apply some vinegar and pry it apart. I used a stiff METAL putty knife. Geeze, what a mess! Everywhere the vinegar seeped or splattered, turned black from the reaction to the metal. Duh!

This could have been a disaster. But, the grey cells finally meshed. Recalling that a friend had bleached some poplar to remove some green streaks, I thought what have I got to lose. Ordered some Oxolic Acid. (Which is the point of this narrative) It arrived yesterday and I mixed a batch. Applied it to the blackened areas and crossed my fingers. Amazingly, after about 20 minutes, the black had totally disappeared, even on the end grain. I was blown away.

So, the stuff really does work. It even cleaned the blackened putty knife. Oxolic Acid will stay in my shop. 

 

Be sure to rinse / neutralize before starting to sand.

28 minutes ago, kmealy said:

Be sure to rinse / neutralize before starting to sand.

Thanks, but why? 

 

Edit, never mind. Figured it out. Acid affects finish, right? 

Edited December 23, 20169 yr by Gene Howe

Interesting info, Gene. I AM one of those people who store random facts in the dark recesses of my mind, and occasionally I get to use one of them. Many years ago I tried to cut the rind off a black walnut (curiosity) and the knife blade turned a disgusting brownish/black colour. Never COULD get it clean. Now I have to find that knife and try the oxalic acid on it! I knew the acid would remove rust stains, now I wonder what else it will remove.

John

3 minutes ago, HARO50 said:

Interesting info, Gene. I AM one of those people who store random facts in the dark recesses of my mind, and occasionally I get to use one of them. Many years ago I tried to cut the rind off a black walnut (curiosity) and the knife blade turned a disgusting brownish/black colour. Never COULD get it clean. Now I have to find that knife and try the oxalic acid on it! I knew the acid would remove rust stains, now I wonder what else it will remove.

John

I'm told it does a great job of removing dark stains on boat bottoms and pontoons. I'm going to try it on toilet bowl rings and plastic shower surrounds. 

28 minutes ago, Gene Howe said:

Thanks, but why? 

 

Edit, never mind. Figured it out. Acid affects finish, right? 

Well, yes it can affect adhesion, but also the sawdust will be noxious especially if you breathe it in.

Thanks for the reminder.

 

I redid our deck this fall and the cleaner contained Oxolic acid. It really brightened the wood surface.

Gene - thanks for the insight.   Should be a good one for the hints and tricks forum.

Health and safety info for oxalic acid...

 

POISON! DANGER! MAY BE FATAL IF SWALLOWED. CORROSIVE. CAUSES SEVERE IRRITATION AND BURNS TO SKIN, EYES, AND RESPIRATORY TRACT. HARMFUL IF INHALED OR ABSORBED THROUGH SKIN.

Health Rating: 4 – Extreme (Poison)
Flammability Rating: 1 – Slight
Reactivity Rating: 1 – Slight
Contact Rating: 3 – Severe (Corrosive)

 

If acid works, what about mild acids such as lemon juice?  Bleach green poplar, hunh?  I'll try that.

7 minutes ago, PeteM said:

If acid works, what about mild acids such as lemon juice?  Bleach green poplar, hunh?  I'll try that.

Save the lemons for G&Ts and pie. The Oxolic is so easy. A long while ago, I tried regular household bleach on wood to no effect. 

16 hours ago, p_toad said:

Health and safety info for oxalic acid...

 

POISON! DANGER! MAY BE FATAL IF SWALLOWED. CORROSIVE. CAUSES SEVERE IRRITATION AND BURNS TO SKIN, EYES, AND RESPIRATORY TRACT. HARMFUL IF INHALED OR ABSORBED THROUGH SKIN.

Health Rating: 4 – Extreme (Poison)
Flammability Rating: 1 – Slight
Reactivity Rating: 1 – Slight
Contact Rating: 3 – Severe (Corrosive)

Don't drink it. Wear gloves. Mix gently.

 

Never got that solution to ebonize anything but it does turn wood sorta grayish brownish blackish greenish like old barn wood. But on second thought my ebonizeish and yours probably are different colors.

5 minutes ago, Smallpatch said:

Never got that solution to ebonize anything but it does turn wood sorta grayish brownish blackish greenish like old barn wood. But on second thought my ebonizeish and yours probably are different colors.

I've only used it on walnut. And then, only on small pieces that could be soaked in the solution. The accidental job on maple did just turn it an ugly grey.