PVA leeching through maple veneer RESOLVED

[Graham Orm]

Any ideas? It's not particularly thin, but it's coming through as black dirty marks that won't sand off. I've had to remove it all. What glue can I use as an alternative to PVA for veneering?

 

[Droogs]

After having had similar probs in the past, I now use hide glue as it doesn't matter if theres any bleed through as I hammer veneer for the most part and it's spread on both side during the layup process. Once dry then scraped off, it also doesn't react with finishes so is ideal for me. Does have a short working time but all you need do is heat it with a hot clothes iron to soften the glue and continue working.
HTH
Droogs

 

[Graham Orm]

After having had similar probs in the past, I now use hide glue as it doesn't matter if theres any bleed through as I hammer veneer for the most part and it's spread on both side during the layup process. Once dry then scraped off, it also doesn't react with finishes so is ideal for me. Does have a short working time but all you need do is heat it with a hot clothes iron to soften the glue and continue working.
HTH
Droogs

I knew that hide glue would be the first thing someone would suggest. I've never used it and for the time being want to 'stick' with conventional off the shelf stuff.

Thanks anyway Droogs. ;-)

 

[Woodmonkey]

Cascamite

 

[Graham Orm]

Cascamite

Thank you ;-) I'll track some down. Have you used it personally for veneering?

 

[RobinBHM]

I believe UF with resin hardener is often used for veneering

http://www.gluesdirect.co.uk/catalog/in ... th=204_206

 

[Beau]

Any ideas? It's not particularly thin, but it's coming through as black dirty marks that won't sand off. I've had to remove it all. What glue can I use as an alternative to PVA for veneering?

Have you any ideas why it's coming through as black?
Used PVA with maple veneers before and had it bleed through in the vacuum press but it's comes through PVA coloured which is normally white and invisible once dry and cleaned off. Can't see why other glues would be less likely to bleed through.

 

[Graham Orm]

Any ideas? It's not particularly thin, but it's coming through as black dirty marks that won't sand off. I've had to remove it all. What glue can I use as an alternative to PVA for veneering?

Have you any ideas why it's coming through as black?
Used PVA with maple veneers before and had it bleed through in the vacuum press but it's comes through PVA coloured which is normally white and invisible once dry and cleaned off. Can't see why other glues would be less likely to bleed through.

Nope, not had the problem before myself, but never used this particular veneer before. I'm assuming it's the glue, just dirty marks that won't scrape or sand out. I cover the piece with white grease proof paper before the caul so nothing from that.

 

[Graham Orm]

I believe UF with resin hardener is often used for veneering

http://www.gluesdirect.co.uk/catalog/in ... th=204_206

Cheers Robin.

 

[Adam9453]

i've got titebond cold press veneering glue which is supposed to be very good, although I haven't actually tried it yet.
got the veneer, got the glue, now just need to buy some time!!!

 

[Graham Orm]

i've got titebond cold press veneering glue which is supposed to be very good, although I haven't actually tried it yet.
got the veneer, got the glue, now just need to buy some time!!!

Where did you get it Adam? I can only find it on U.S sites

 

[Adam9453]

I got it from axminster, here's the link;

http://www.axminster.co.uk/titebond-col ... for-veneer

 

[Graham Orm]

Thanks Adam, Found it!

 

[Adam9453]

Thanks Adam, Found it!

No problem

It gets great reviews and being titebond I expect good things from it

 

[JJ1]

I've veneered about half a dozen small projects so far, so not the most experienced on the subject. I used Titebond Cold Press glue (bought from Axeminster) and no complaints whatsoever and certainly no bleed through.

 

[PAC1]

Graham, I am delighted you have resolved the problem but for my education could you explain the cause of the black marks and the solution?

 

[Graham Orm]

Graham, I am delighted you have resolved the problem but for my education could you explain the cause of the black marks and the solution?

I really can't. Just black inky stains that weren't there before I clamped it up. The next closest thing to it was greaseproof paper so nothing came off that. It went straight onto wood so nothing to come through from underneath. It's taken me an hour to strip the veneer off, scrape and sand the surface back to a flat clean surface.

 

[Woodmonkey]

Cascamite

Thank you ;-) I'll track some down. Have you used it personally for veneering?

Yep used it several times with no issues. It's got a nice long open time too which can be useful on more complicated jobs

 

[Graham Orm]

Cascamite
Yep used it several times with no issues. It's got a nice long open time too which can be useful on more complicated jobs

Thanks WM. I've ordered some Titebond veneering glue now so I'll go with that for now,but will bear Cascamite in mind.

 

[custard]

I've only veneered Maple a handful of times, but I've veneered hundreds of square metres of Sycamore which is a closely related species. Bleed through is the biggest problem, most makers using a UF glue go for the fastest hardener they can find as once the adhesive has set there's no longer a risk of bleed through. Heating the press is another strategy for speeding up pressing times. The other main option is thickening agents, which are mixed with UF glues to block the veneer pores and prevent bleed through, there are commercial UF thickening agents available which are added at 10-15% by weight, but I've known people use corn flour and achieve good results!

If all else fails you could use paper backed veneer which kills the bleed through problem dead, or alternatively size the veneer with glue size first, a giant faff but it's also a reliable solution.

Veneering PVA's (such as Titebond Cold Press) are also popular as they reduce both the risk and the impact of bleed through, they also have the advantage over UF glues that UF resins can sometimes cause a green tinge that's particularly noticeable on the most desirable, very white grades of Sycamore. i've never heard of, nor experienced, a black stain. Complete guess but I wonder if there was some iron dust/filing contamination, maybe if something like steel wool had been recently used in the vicinity?