I get chips in the varnish down to the bare teak and often by the time I find them the wood is stained black ' I have tried different teak cleaners and regular household bleach without any luck .If I sand them out I remove a fair amount of wood which I don't want to do. Anybody know of a good product ?
If the wood is black try Bar Keeper's Friend (the active ingredient is Oxalic Acid). Lightly spot sand the area by hand, just enough to open the grain. Make a paste by adding a bit of hot water to the powder. Then, if it's just a small spot, dab it on with a q-tip. Let it dry and then remove it with a very stiff brush. Repeat as needed until you're satisfied, then re-varnish.
Be aware, it may also remove some of the natural wood pigment, leaving the spot a bit lighter than the neighboring wood. So experiment in an inconspicuous spot if possible. This sounds like it's a mold issue, but it also works in areas where the wood's been blackened by nail heads or other iron objects.
I have used lemon juice to remove cat urine stains from oak flooring. Never tried it on teak. Like any thing new, I would try it on an inconspicuous spot, or a piece of scrap to see what it does to the wood.
Or you can buy oxalic acid in the form of "wood bleach" at any hardware store. I also have a sail boat with lots of brightwork and this works great. You mix it with warm water, apply and leave it for several hours, hose off and let it dry.
Then sand lightly and re-coat with varnish and it usually blends right in.
Thanks guys - I found I had some oxalic acid powder from long ago that I forgot about . I never tried it as a paste or left it on that long, either of which should do the job . Thanks again