PVA discolouring oak

[RossJarvis]

For whatever reason I've usually wiped fresh PVA off joints with a damp cloth. I've found with Blue Evostick that this causes a reaction that blackens the oak. Has anyone else noticed this, what should I do instead?

 

[undergroundhunter]

Leave the glue to fry and chisel off after it either dry or partially dry. The discoloration is likely caused by the water in the glue.

Matt

 

[Phil Pascoe]

I've not tried frying it.

There has to be acid involved somewhere I would think, in the presumed absence of iron.

 

[woodbrains]

Hello,

I think there must be some iron or steel involved somewhere. Perhaps a contaminated cloth or impure water, or some tool used as a removal tool !Ike a chisel or scraper, perhaps some iron filings or steel wool shards, or some contact with steel clamps. I've never known Blue evostick to stain oak when just removed with a damp cloth and nothing else. PVA is actually rather acidic itself, so I'm not sure another acid would make any difference.

Mike.

 

[marcros]

nothing silly like a screw or nail in the top of the glue bottle, bunging up the hole when not in use, is there?

 

[RossJarvis]

Hello,

I think there must be some iron or steel involved somewhere. Perhaps a contaminated cloth or impure water,
Mike.

Ah...... I've realised I used the wrong cloth to wipe the glue away with........There is "ahem" a strong chance I used the one I wipe chisels with after sharpening them #-o I think I need to colour code them rather than using the same torn sheet for everything. Now if I used an oilstone and not waterstones this may not have occurred.

 

[Phil Pascoe]

No, you'd have oil throwing the polish off instead.
I use one of the huge rolls of heavyweight kitchen paper and just throw it away as I go - I've been caught out too many times.

 

[cedarwood]

It's funny this post should come up just now as I have had the same thing happen to my latest build, on all my other projects i have allowed the glue to set then removed any excess which was all fine. On this build I decided to wipe off the excess with a wet piece of paper towel and on all joints where I did this there was a blackening of the oak, conclusion was that the contamination came from either the water or the sand paper used. I was using titebond 3 ultimate for the first time due to it's longer open time so went back to premium 2 but it made no difference.

 

[RossJarvis]

It's funny this post should come up just now as I have had the same thing happen to my latest build, on all my other projects i have allowed the glue to set then removed any excess which was all fine. On this build I decided to wipe off the excess with a wet piece of paper towel and on all joints where I did this there was a blackening of the oak, conclusion was that the contamination came from either the water or the sand paper used. I was using titebond 3 ultimate for the first time due to it's longer open time so went back to premium 2 but it made no difference.

The first time I noticed this, with the same glue was on an oak veneered door, on that occasion I'm pretty sure the cloth was not used anywhere near the chisels. I think I'll just stop wiping with damp cloths on oak. As phil.p says I'd probably only end up wiping oil on :?

 

[Northern woodworm]

I've had the same issue with iron clamps touching the oak/wet PVA. I assumed that it was similar chemistry as used to create ink from oak galls and rust in the middle ages:

https://en.wikipedia.org/wiki/Iron_gall_ink

 

[Stormer1940]

Water and oak just don't mix well. It will be the dampness in the cloth. Scrape surplus off with a filler knife, let it dry and clean up.

 

[Bodgers]

For whatever reason I've usually wiped fresh PVA off joints with a damp cloth. I've found with Blue Evostick that this causes a reaction that blackens the oak. Has anyone else noticed this, what should I do instead?

Do you need to use the water proof PVA?

I have used both Titebond II and Evostick Green quite a lot on white Oak and I don't have this problem. Oak is quite opened grained though so you have to be very tidy with clean up on the glue up.

I don't think it is the water content that causes the blackening... unless your water has high levels of metal in it or something. The only thing that comes close to this with water is if you leave a wet cloth on wood for a few days you can get black mold build up.

If it does have to be water proof, more expensive, but you could go for epoxy...

 

[Droogs]

Do none of you mask your joints before gluing up?

 

[Sheffield Tony]

I don't think it is the water content that causes the blackening... unless your water has high levels of metal in it or something.

I wonder how much iron is needed to cause a problem. Here at work, our water comes through an old cast iron main. If you fill a pint glass, it has a rusty hint to it. I would not be surprised it it were enough to cause a problem. But at least anaemia is unlikely :lol: