Search results for query: oxalic acid

...advised me to use to some wood bleach on a few areas that couldn't be sanded out. I used Liberon wood bleacher, which is apparently oxalic acid, and the result looked fine, no visible difference overall between the bleached wood area and the non bleached. Then I applied Blanchon Wood Oil...

It will if it any remaining is unreacted. Oxalic acid is supposed to be very thoroughly removed from treated wood anyway, with at least two rinsings using fresh water each time. This is for safety reasons apart from anything, oxalic acid is quite poisonous.

Will the Oxalic acid get the old finish off? I might give it a try as I already have some knocking about somewhere. regards Brian

Thanks for the replies. I am pretty sure it is mould, so will have a go with the vinegar first. If that fails, I will source some oxalic acid. I will let you know the result when I have hopefully rectified it. Thanks again Simon

I would scrape or sand the surface lightly and see if the stains go, other than that maybe a weak solution of oxalic acid (make sure you wash the surface of the wood down really well after using oxalic) lightly sand then refinish. Matt

...steel fittings on the gates. Oak is particularly prone to it. Although this kind of staining can sometimes be lessened or removed using oxalic acid you should be prepared for the possibility that the stains may be permanent. If you want to try removing the stains using oxalic acid it's...

It may be possible to bleach the oak back to an acceptable colour using a solution of oxalic acid crystals. This needs to be done with due care since the acid is toxic. You can find information on the safe handing and use on - WWWconstructionchemicals.co.uk

...the way, are you sure it's mould and not fragments of iron from your bench or hands, reacting with the tannin in the Oak veneer and turning black? If it is you'll have to go the Oxalic Acid route, again use all over but be aware it'll fade marquetry colour so will require some corrective...

...be iron in the water, and perhaps distilled water might reduce the chance of it occurring, but I really don't know if that would help. Like you, I've resorted to removal with a little oxalic acid, although I've also tried a few careful localised dabs of domestic bleach with some success. Slainte.

...good many years in full sun. Have tried hydrogen peroxide to lighten it, but without much success. Somewhere, was pretty sure I had some oxalic acid, but can't now find it. The rhubarb has all died back for winter, so can't fudge with that. Question - is the lightening that might be gained...

Oxalic acid will remove the stain but I agree with Woodmonkey, plain it off when it has dried. Jim

...stains out and nothing has worked. I've tried sanding, Leaving overnight with bicarbonate of soda water mix on stains, heating with hair drier, varnish remover and Bicarb, and Oxalic Acid. None of these have remove the stains, and there are still dark patches around the handle... Pleas help...

...be regular bouts of fallout of cast iron dust from the factory extraction system. At that time the 'cure' was to wash your car using an oxalic acid solution. The issue arose again in about 2003 when roof repairs dislodged old dormant dust - at that time I had my car valeted using a 'clay bar'...

Cat pee on your table. How gross is that. Since the standard way of darkening oak is with ammonia, and cat urine contains ammonia, I would expect a difficult job. If you omit the job of rinsing off the oxalic acid, it might with a bit of luck just be enough to see off the cat ?

That sounds highly plausible to me from my recollections of Yorkshire's often very soft, peaty and therefore presumably acid water which could easily carry iron impurities. Jim

removing the finish preferably with paint stripper (old type!) then applying oxalic acid would be my chosen path. These type of marks can be stubborn to remove. If oxalic doesnt work, I do find that using old style stripper (DCM) and wire wool and scrubbing quite hard with the grain will often...

...no good, the oil stain showed an even deeper colour. Had to meths off the sanding sealer and re-sand. Have been using a fairly strong oxalic acid solution delicately applied with a cotton bud... and although the oxalic acid is doing it's stuff, in as much as it has slightly bleached outside...

Thanks for further replies. I now have a tub of oxalic acid, and a bag of ferrous sulphate is on its way. I'm not too worried about the toxicity of the acid - if any very tall person starts chewing on my my joists though I'll try to stop them :wink: I need to experiment and will report back -...

...which I believe is also known as Tiger strip is for many very attractive. The existing dark stains may well be almost removed by using oxalic acid which is both very easy to use and easy to buy. This would be my prefered route rather than trying to remove them by sanding. I would use Tung...

Iron or steel and Oak do not mix, just try putting a bit of steel onto a damp piece of oak and leave it for half an hour, that's why there are black marks around the nail holes. The Oxalic acid may tone them down a tad but if all else fails try staining them with a dark Oak stain. Andy