I have an old, old cedar boat built before the days of epoxy. It has a lot of staining and is covered with patches of fiberglass and wood filler ect. I have stripped the glass patches and old varnish and now I will be trying to remove stainging that remains on the wood.
Stains from reaction to metal fasteners, tanins and mildew make the surface look like a mottled mess. I want to remove staining and restore a more natural color. I do not want to bleach the wood fibers.

Please offer your suggestions and any help you can. I am leaning toward oxalic acid and sodium percarbonate washes.

Thanks
Robert

I've used oxalic acid a couple of times with variable results. On one occasion, some pink stains showed up months after the project was completed- whether this was a result of poor rinsing, or some other reason, I don't know. Oxalic acid will change the colour of some woods.

Your idea of rinsing with water / neutralizing with washing soda will work. (you need a base aka alkali to neutralize the acid).

Be a bit careful with the oxalic acid- it's not entirely 'healthy'. Make sure you rinse the surface well to avoid breathing sanding dust with oxalic in it- but your dust mask should prevent that.