Damage to white oak table top

[wolfden]

Someone left a metal can on my son's white oak table top for some time. The table is on his covered deck. It left a nasty round stain where it sat. See photo. I don't know what to do to remove the ring. I finished the top originally with a poly/blo mixture. I'm afraid that the stain has penetrated deep into the wood but I don't know. Any help on how to refinish the top and remove the ring would be GREATLY appreciated!
Andy

 

[creasman]

The iron in the ring has reacted with the tannin in the oak. This is the same process used to ebonize oak and other woods. Oak, in particular, has a high tannin content. Unfortunately, this stain likely goes deep. Before trying to sand it out, I'd look for a chemical solution -- something that reverses the reaction that caused the stain in the first place. I don't know if that is possible, but hoping others here on the forum will know.

 

[wolfden]

The iron in the ring has reacted with the tannin in the oak. This is the same process used to ebonize oak and other woods. Oak, in particular, has a high tannin content. Unfortunately, this stain likely goes deep. Before trying to sand it out, I'd look for a chemical solution -- something that reverses the reaction that caused the stain in the first place. I don't know if that is possible, but hoping others here on the forum will know.

Thanks, that was what I was afraid of

 

[wolfden]

I saw on another forum that lemon juice can remove some of the stain. Any thoughts out there on that?

 

[jfynyson]

Historically oxalic acid solutions have been used in furniture restoration. You'd apply the solution to then entire table top after sanding off the finish to ensure you do not get uneven tones from the treatment area only. If that doesn't work well enough you could use a stronger acid but like hydrochloric or phosphoric but you'll of course need to be more careful. The acids will dissolve the iron that reacted with the tannic acids in the wood. The staining may not fully disappear but may be acceptable or you could then experiment with adding some dye stain to the entire table top to mask what discoloration remains. In either case you'll need to neutralize the acids somewhat and rinse well.

 

[wolfden]

Thanks greatly! I understand JUST enough chemistry to understand what needs to be done. It isn't going to happen quickly I imagine!

 

[Graywolf]

Sorry to see you have problem, you are going to be stuck with some damage but like Jeremy is saying is true. It’s a process that will more than likely have to be repeated a couple to a few times to remove what can be removed. Good luck and please share you adventure.

 

[wolfden]

Yeah! I'm afraid I'll be working on this for a while. I'll try to send pix after each "treatment."

 

[Wiley's Woodworks]

If oxalic acid is first choice for the chemical cure of the stain, you're in luck. Bar Keeper's Friend is full of oxalic acid. I mix it with penetrating spray lubricant into a slurry and use it to remove rust from tools. Works like a champ.

 

[FredP]

If all else fails you could route a Chanel and inlay a fresh piece of oak or take the top off and rip the area out. Replace with new slat.

 

[tri4sale]

If all else fails you could route a Chanel and inlay a fresh piece of oak or take the top off and rip the area out. Replace with new slat.

that's a good idea, route out a shape like a heart of another material and inlay it in the damaged area, make it a feature.

 

[Jim Wallace]

It may not be as deep as you think. My first thought would be to try a card scraper. To keep the surface reasonably level take one pass over the stain then one to one side then one to the other etc.

 

[HMH]

I like Fred’s idea personally. If the best possible outcome of the fairly labor intensive sanding/ chemical treatment process is a lighter stain, I’d embrace it, and make it a feature - either w/ an attempt at a species/ grain matched patch, or a contrasting species entirely. It will certainly gain some character either way!