Veneer bubbling- help!

[tktran]

Veneer bubbling- argh! Post #1

Last weekend I noticed that my home-made Tassie Myrtle veneered stereo speakers have bubbled. The veneer was applied only 3 months ago using the "PVA wood glue on MDF and veneer-wait for both to dry-then iron on" technique. :-)

It must be due to the heat because every afternoon sunlight comes streaking through the glass sliding door into our living room and falls directly onto the outer surface and top of left speaker. At first I wasn't very concerned but now both these surfaces are have bubble extensively.

Does anyone has ideas of how to fix this? Ordinarily I'd just re-iron out the bubbles, but the problem is I've already oiled and waxed (Danish oil and fine paste wax) the speakers.

Please help!

I hope to have some pictures up of the bubbling problems tomorrow.

http://members.iinet.net.au/~magius

[echnidna]

I would be inclined to put a piece of light cardboard over the bubbles and iron them down again. The finish may be affected but I think that rewaxing might be the only fix you will need to do.

[journeyman Mick]

I'm intrigued! I've never heard of PVA being used like a contact-type iron on. Any where I can go to read more about it? Not that I'd be likely to use it mind you, as with my local climatic conditions PVA tends to be a temporary glue.

Mick

[bitingmidge]

I'm intrigued! I've never heard of PVA being used like a contact-type iron on.
Could explain the bubbles! ;)

An old trick that works if you are careful AND patient, (also good for bubbles in picture mounting if you don't use too much "wet", and have no alternative!).

Get a syringe of the very fine type, I think the disposable ones used by diabetics will do fine, and they are available over the counter at your local pharmacy.

Thin the PVA until it can be forced through the syringe.

Carefully skewer a tiny hole in the veneer to one side of the bubble to allow air to escape (and glue). Don't worry, it will be virtually invisible after the moisture of the glue gets to it.

Now inject enough glue into the bubble to ensure a bond and carefully work the air out of it.

Clean off any glue squeeze out with a damp cotton bud. This should not cause any grief on a waxed surface.

Place weighted board over the bubble for a few hours.

Don't forget to store or dispose of the syringe carefully!

Good luck!

P

[echnidna]

The original PVA should reactivate with heat unless its gone old and crumbly.

Forgotten where I learned that pva will reactivate with heat, it was so long ago.

[echnidna]

It makes it very easy to do a small veneering job, just coat the back of the veneer and the substrate let them dry then iron them together.

[tktran]

Thank you for all the replies.

Here are my speakers BEFORE the bubbling
http://www.woodworkforums.ubeaut.com.au/showthread.php?t=7795

Ordinarily I'd just re-iron, but I love the finish too much. Does anyone knows what happens to Danish oil and Liberon wax when heated?

Come to think of it I will have to try it on a scrap piece first.

Here is the technique I use for veneering using PVA glue. It is supposed to work ok without long-term issues. Journeyman Mick- please see this post
http://www.diyaudio.com/forums/showthread.php?postid=238062#post238062

Hmmm but I guess sunny Perth is a bit different to Bucks County, Pa?

As you can see, the reactivation of PVA under heat is the principle exploited for the veneering process. Which probably explains why prolonged heat exposure, ie. direct warm afternoon sun is causing the veneer to lift off the substrate.

I still need to take pictures of the extent of the bubbling. Have moved them out of the sun into another room, but now have problems with the digi-cam.

Not having much luck this week...