# Black stains when gluing red oak



## DonG1947 (Nov 14, 2012)

My first post and I have a problem!

I'm building a 48" round red oak pedestal table. I glued up the first 2 boards using Titebond III. Used a damp rag to wipe off the squeeze out and let the glue dry overnight. Wanted to make sure all the glue was off since the table will get a light coat of stain. This morning, there were black stains in the grain where the wood was moistened.

Questions:

1) How can I get rid of the stains around the glue line without changing the natural color of the wood?

2) How can I prevent stains on the other boards and still get all the glue off so I can stain the top when I am done?

Thanks for your help.

Don


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## cabinetman (Jul 5, 2007)

DonG1947 said:


> My first post and I have a problem!
> 
> I'm building a 48" round red oak pedestal table. I glued up the first 2 boards using Titebond III. Used a damp rag to wipe off the squeeze out and let the glue dry overnight. Wanted to make sure all the glue was off since the table will get a light coat of stain. This morning, there were black stains in the grain where the wood was moistened.
> 
> ...


I've seen that condition a few times. To the best of my knowledge, the cause could be from the water in the glue reacting with the tannins in the Oak. One thought it could be from what was used to machine the edges being glued. If metallic deposits were left on the mating surfaces, it could turn black when a waterbased glue is applied. For a preventive fix if this was the cause would be to wipe down the mating edges with acetone before applying the glue.

It's also possible that the particular supply of wood you have came from a fungus infestation in its growth. As for a fix, you may have to use a non waterbased glue, like an epoxy. As for a way to get rid of the black, you can try oxalic acid.

At the time, none of my suppliers had a definitive answer. I will say it didn't happen with an epoxy with the same group of lumber.









 







.


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## ed_h (Dec 1, 2010)

This is normally a reaction between iron and tannins in the oak fostered by the moisture in the glue.

Keep ferrous metals away from wet oak. (clamps or steel wool are common sources)

I doubt you'll be able to remove the stains completely. You could try oxalic acid, but it will change the color of the oak.


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## DonG1947 (Nov 14, 2012)

Thank you for the quick replies. The dark spot is not just at the glue line, but throughout the area that was wet. Maybe the tap water? Will try wetting 2 pieces--one with tap water and one with distilled water. I will report back.

Don


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## Improv (Aug 13, 2008)

Try TBII on a test scrap and see if it discolors.


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## DonG1947 (Nov 14, 2012)

Well, I think I discovered the cause of the problem. I wet various pieces of red oak including the backs of the boards that stained. Used tap water, distiled water and pieces on which I smeared some glue. No stains on any of them. Decided it was a contaminated rag. I am restoring a 47 Dodge pickup in the garage, but sometimes I grind and cut metal in the wood shop in the basement. The rag I picked up must have been contaminated with metal filings which lodged in the grain of the wood.

A couple of you mentioned metal as a possible source and it made me think. After all the other variables were tested must have been the rag.

Thanks for your help. Seems like a great forum. I'm sure I will be a frequent visitor.

Don


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## Steve Neul (Sep 2, 2011)

I've never had black stains on oak that weren't very superficial. What I've had sands away easily.


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