Replies

1. 
   saschafer | Dec 06, 2007 05:53pm | #1

   I've never used wenge veneer, but given its coarse grain structure, I can easily imagine how glue would penetrate it. The usual technique, regardless of wood species, is to seal the back side of the veneer with shellac (e.g., Zinsser Seal Coat) before glue-up.

   -Steve

    

2. 
   ring | Dec 06, 2007 06:20pm | #2

   I subcontract veneering to a shop which specializes in it, and they've done many dozens of glue-ups for me using wenge on ply or MDF. The solution we arrived at (after encountering problems like you describe) is to pre-stain the glue with dark walnut stain, so that any bleed through eventually disappears into the finish.

   David Ring

   http://www.touchwood.co.il/?id=1&lang=e

3. 
   Castlewerks | Dec 06, 2007 07:08pm | #3

   Tom,

   I have had some success using Unibond glue mixed with their blocking agent (Unibond Blocker) to minimize (but not eliminate) bleed through.

   http://vacupress.com/veneerglue.htm

   From your post it sounds like you had a tough time with the glue in general. I don't have a lot of veneering experience, but the Unibond has always worked well in my applications. As for the Unibond Blocker, I recently completed a project with birds eye maple veneer and I still had some bleed through with the blocker, but it wasn't too bad.

   Cheers,

   Michael

1. 
   tom77 | Dec 06, 2007 09:42pm | #5

   Thanks to all of you for your suggestions. The shellac sounds like a good idea. Does the alcohol cause the veneer to buckle like water does? That would be an interesting experiment.The coloring of the glue does work well. This cold press glue is a good color match to the wenge. That is the only reason that I could proceed. But you can still see the spotted areas. (like looking at a leopard in a dark room)I have used Unibond a lot in the past, but have started using cold press glues because my shop is in a cool basement. The cold press glues have worked well in my environment, and the cycle times through the vacuum press are much faster. (45 to 60 minutes)Thanks again to all. Very interesting information.Tom

4. 
   SantaFeTom | Dec 06, 2007 07:29pm | #4

   I had a similar experience with quilted maple veneer which I cut too thinly and pre-catalyzed urea formaldahyde glue (a powder mixed with water). Thinking all was lost, I experimented with sealing the back of the next batch with shelac. The shelac bled through but I was planning to use a shelac sealer coat on the front anyway so figured I would be OK. I then sanded both the glue bled through and shelac bled through pieces and to my surprize sanding fixed both pieces and all was not lost. So my recommendation would be to try using urea formaldahyde glue.

5. 
   Russell | Dec 06, 2007 09:46pm | #6

   Hey Tom,

   I've veneered with wenge a number of times and here's what I've learned. First, I use unibond 800 with a dark catalist which pretty much matches the color of wenge in the event of bleed through. I also use the uniblocker, which helps, but because wenge is so pourous doesn't always solve the problem. The only way to make sure that bleed through isn't noticable is to fill the pores of the veneer before finishing. That's what's happenes with the glue bleeding through, it's filling the pores of the wenge making a totally smooth surface and on a wood this pourous the difference between the filled and unfilled pores is very evident. Especially if it's reflecting light. What type of finish did you use? If you used an oil, varnish or shellac you might be able to make the problem a little less noticable by using Andy Rae's home made top coat finish that's a mixture of one part boiled linseed oil, one half part quick drying varnish and one part paste wood filler (dark for wenge). Here's a link to the video, you can take a look and see what you think:
   http://www.taunton.com/finewoodworking/subscription/SkillsAndTechniques/SkillsAndTechniquesArticle.aspx?id=26295

   Hope it works out for you. Cheers for now.

   Russ.

   http://www.jensenfinefurniture.com

1. 
   tom77 | Dec 06, 2007 10:12pm | #7

   Russ,Thanks for your reply. I used a penetrating finish, oil and varnish, after sanding to 400 g. I can see that filling the surface would eliminate the problem. (just took another look) After reflecting on this entire discussion, coloring the glue will not fix the problem. It just masks it. If there is a lot of bleed through, even that masking is not adequate.I checked out your website. Nice work!Tom.