Veneering Dilemma

Hello

Another happy customer of our DVDs asks a question about veneering:

Hi David, my wife bought me your DVD on hammer veneering a while ago which I enjoyed immensely and also learned a great deal from. To date I’ve been reasonably successful in managed to veneer some small panels with stringing and cross-banding. Easier when you know how! However,  the whole process got me thinking on why panels are cross-banded like you demonstrate, or at all, for that matter? I’d always been told that its to give some sort of structural support to the central veneer.

Anyway, I’m digressing slightly here: In the last few weeks I’ve been making a small dovetailed sycamore and wenge box with a veneered ripple sycamore lid. I  wanted to experiment by not having any cross-banding or stringing on the lid, and just wanted to let the ripple do all the talking, so to speak. So I constructed a panel of maple 10x20mm around an MDF core. I let it dry and then,with a very finely set plane, thanks to your “how to use a hand plane DVD”, I levelled the maple framework almost seamlessly with the core MDF.  I then laid 1 sheet of the ripple sycamore on the reverse to counter-balance a similar single sheet on the face. After drying , trimming and a little hand sanding, the surface looked good and all seemed well. I was very happy with my work up to that point. The surface, along with the rest of the box, was now ready for the finish. I left the box and lid for about a week but when I came back to it today I can distinctly see where the panel meets the MDF core; there is a slightly, but definitely distinct, raised line/edge both on the face and its reverse. It really looks like the maple substrate panel had expanded (in thickness) lightly leaving a horrible ridge.
I’d have expected it to be relatively stable, due to its small size, or, if anything, to see it shrink because I brought it out of my rather cold workshop and into the warmth of my house, where it has remained for a week of so. Any thoughts on why  this raised line has occurred? I’m a little cautious about sanding it out further as I don’t want to go right through the veneer but that looks like the only option open to me now.
Regards
Paul
 Hi Paul

What you are seeing is what is called “telegraphing through” It is exactly what you say the edge lipping is moving. There are a few things we do to help avoid this.

1. Most important keep the lipping as small as you can 10 by 20 on a 10mm panel is big we would aim to use 10mm by 5mm

2. You need to have really well dried stuff both the panel and the lipping well conditioned to the workshop . We take a moisture reading every day for a couple of weeks if we can . When it stops moving its a good un

3. I always try to hot glue veneer both sides in one session to avoid warpage and stress on one side . This may be a part of it as well.

4. Sycamore and maple are very translucent we often put two layers of these veneers laid one on top of the other to cover the line where the lipping shows up.

Its a pain !

Hope this helps

Very best

David

 

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