Restoring an old chest - wood discolouration

[Nick67GT]

Hi everyone, I'm new to the forum, so please excuse me if this problem has been covered previously.

I have just started to restore an old carpenters tool chest, which is made from pine and has hardwood edging around the lid. Having just stripped the lid so far of its thick black paint, using Nitromors + careful scaping & fine wire wool, I am left with discolouration of the base material.

I've tried all kinds of solvents (white spirit, turpentine substitute, meths, cellulose thinners and even brush cleaner) to try and remove the problem, but they won't touch it. Obviously, I could take the sander to it and solve this in 5 minutes flat, but I want to retain the age related marks, albeit with a new wax finish.

Has anyone dealt with a similar problem before and can pass on a few tips to deal with it?

Thanks in advance - Nick.

 

[AndyT]

That old paint was good stuff!

I'm afraid I don't know of a quick fix, but I can confirm that almost all old tool boxes like that were painted black on the outside, so assuming you want to keep tools in it, I suggest you paint it black again and learn to love it looking that way.

If you want a blanket box for the bedroom, use the tools to make a new one!

Welcome to the forum btw.

 

[ED65]

If this is paint staining I don't think there's any solution for this other than to take some wood off the surface Nick. Almost any stripping will leave some staining of the wood underneath, or stubborn bits of paint stuck in the grain.

Can you clearly see this is paint in the wood though? In the photo it looks quite like water-related stains, which can occur through covering paint. If that might be it you could try a cleaning product specifically made for tackling those, but oxalic acid probably does the job better than anything.

If you get oxalic handle with caution, it's quite toxic to the person using it.

Obviously, I could take the sander to it and solve this in 5 minutes flat, but I want to retain the age related marks, albeit with a new wax finish.

Lots of people working with reclaimed wood face the same dilemma of wanting to get the wood fairly clean but not remove all the signs of age and the balance is hard to achieve.

Worst case you could always sand it until it's as clean as you want, then distress it back to how you think it should look.

 

[Stanleymonkey]

Are you stripping the paint from the sides and base of the box as well?

Could you have a go at sanding in a less noticeable spot (maybe underneath) if there is similar wood and dis-colouration on that face.

Might help you decide what to do with the whole box

 

[Nick67GT]

Thanks for the input so so far. I fact, I had a suspicion that the visible staining was going to remain a permanent feature after my efforts with the other solvents I mentioned........

Concerning Oxalic acid, is this the same as 'deck cleaner' as found in B&Q and the like? Is there a particular brand that performs better than others or can I actually buy the product in a 'pure' form rather than something marketed for a certain use?

Thanks.

 

[Nick67GT]

OK - have sanded the underside of the lid (which was turquoise....) to see what it would come up like.

Damage is minimal and wood colour is what I was hoping to achieve.

And yes, I do intend to strip the whole of the outside!

 

[oakmitre]

Regards paint stripping. **** It is essential that you wear good eye protection at all times ***

Paint strippers work by either dissolving,softening,swelling,washing away or chemically attacking the paint layer.
Lacquers dry to leave a film but can be mostly redissolved later, although there is always the possibility of chemical changes beyond simple film forming which can form an undissolvable substance,e.g. a reaction with the wood or as a result of UV light.

Paints/varnishes etc dry and then cure, which usually involves cross linking. They cannot be dissolved but they can be softened or caused to swell to allow them to be scraped away.The swelling can also cause a weakening of the adhesion between the wood / metal and the paint. An example of this would be Acetone swelling oil based paint or removing paint sprayed on metal with acetone and a scouring pad.

The solvents you have mentioned are not going to remove paint by dissolving, they may cause swelling but probably not.

If you are using Nitromors purchased in recent memory, then it is not the same as it was years ago.The best way to use it is to paint a thin layer on, and masking tape combined with polythene freezer bags (the Tesco value ones are good, semi see through) to prevent evaporation, and leave it a couple of hours before gently scraping off.

Nitromors of old contains Methylene Chloride, a nasty chemical which is harmful to every organ in the body. It works by chemically attacking the paint, it is messy and still requires scraping.

With reference to Oxalic acid as mentioned by ED65 - I think he was referring to water damage in which (mostly) Iron in solution gets into the wood and reacts with tannin turning it black.Oxalic acid forms a complex with the black iron compound allowing it to be washed away, removing the stain.Oxalic acid will not remove most other stains.The crystals are very sharp at a microscopic level, if you breath them in - they cut the inside of your lungs.

I think what you have on your box is probably carbon black based, as most black paints are. Carbon in its elemental form does not dissolve easy in solvents/acid/alkali or react with much at all. You may be able to loosen it by using Nitromors to attack the binder and gently scrubbing with a toothbrush or nail brush, but probably not.

I would try as a no risk experiment, using baking powder or similar and small amounts of water to make a paste. Scrub with the grain using a cheap stiff supermarket toothbrush or the green part of one of those cheap 5p sponges and see what happens.

 

[thetyreman]

I would scrape it with a cabinet scraper to remove the discoloured surface layer, if that doesn't work, then a very very fine shaving with a smoothing plane would be faster than sandpaper, I'm talking thousands of an inch.

The only paint stripper I have used that I liked was made by homestrip, it is a natural product and contains no toxic chemicals, very expensive but it works well.

 

[Nick67GT]

Right, an update.

I have used a mild abrasive paste (used for cleaning granite Worktops and the like) along with a sponge to try and lift some of the remaining black 'stain'

A quick rub on the sides and then the top surface resulted in a reasonable amount of the residue being removed without any loss of the age related marks. I'm happy with this approach (although the actual wood colour has not changed that much....) and might try the same paste with wire wool as the final cleaning process before applying a wax finish.

Any recommendations for wax types that will give a nice shine if possible?

 

[ED65]

All paste waxes with a bit of carnauba in the mix should be approximately equal as far as shine goes, the main secret is to leave as little of it as possible on the surface and buff hard.

You can make your own wax polish very easily if you're interested in that sort of thing. You can get the waxes on ebay, there's a good seller there who was plugged recently, their prices are dead reasonable and they post free within the UK.

 

[rafezetter]

Before you wax - if you've not done it yet, I would recommend you give it at least 1 treatment of danish / tung oil / heavily thinned polyurethane (preferably oil based) or better yet either sanding sealer or a weak cut of shellac. This will add only minimal protection but will make it significantly easier to wax and you'll get a better result from the wax, as on it's own applied to raw wood wax can be quite lacklustre unless you are prepared to give it several coats and LOTS of elbow.