Stains in Oak Floor

[Murray in Toronto]

A friend of mine is fixing up his rental unit. There was carpeting over oak floors and he is trying to restore the hardwood floors. Problem: Earlier tennant had a dog that urinated on the carpet and thus stained the oak under it. The stain has penetrated the wood very deeply leaving dark splotched in several places. He has tried sanding and of course that only affected the surface. He has tried peroxide and household bleech. Again no positive results. Is there any other approach he can take to remove these stains save ripping the floor out or covering it again with a carpet?

TIA Murray

[Brian @ Muir]

I would give WES Distributors in Delhi a call and ask for Tim or George. They sell floor finishing material and refinish floors and also sell ML Campbell lacquers and toners and I am thinking of toners for your application if the floor has a stained finish and I don't mean urine stain. They also have classes on spray finishing. They are very helpful country people and every phone call is important. Sounds like I have a vested interest but I am just a very satisfied customer who has been helped numerous times. Ph# 519 582-2621

[Steve in Richmond]

I've successfully removed water stains from oak in the past using oxalic acid. Sometimes you need to apply it two or three times if the stains are really bad.

[Murray in Toronto]

Thanks Brian and Steve. My friend is going to give the oxalic acid a try.

Murray

[Paul O in Paris]

Murray!

Oxalic acid will remove the colour from the wood, so your buddy may end up bleaching the whole floor! Any kind of urine on a wood floor is bad news as it reacts with tannin and is almost impossible to get out: smells bad too. You might want to consider staining the floor as dark as the affected area as an easier way out, then a coat of waterbased floor finish.............Paul

[CraigL]

Oxalic acid will remove the colour from the wood, so your buddy may end up bleaching the whole floor!

paul, i had thought one of the benefits of oxalic acid as a bleach was that it _didn't_ affect the overall colour of the wood too much. it mainly targeted black iron stains, black water stains and weathering marks. peroxide and chlorine bleaches were what really stripped the colour out.

i've not used any of the three, i'm just asking. the oxalic acid usage i remember from a jeff jewitt book i read sometime.

thanks,

CraigL->Thx();

[Paul O in Paris]

paul, i had thought one of the benefits of oxalic acid as a bleach was that it _didn't_ affect the overall colour of the wood too much.
CraigL->Thx();

Craig! Oxalic Acid will remove wood colour. It's great at getting the black rings out, but it will lighten up the surrounding area too, especially on darker or high tannin woods. This can sometimes cause irregular colour distribution when refinishing. What I usually do is put the warm, concentrated solution on the stained area, I'll even add more crystals if the stain proves stubborn, then slowly add warm water from a squeeze bottle, gradually spreading out onto the surrounding area. This feathers out the lightened area. Usually I end up flooding the whole piece, which is why I wondered if using this method on a floor was time effective. You also have to be real careful to get it all off before sanding as any crystals/dust will really hurt your lungs. Regards...........Paul