working with mahogany crotch veneer

[mr_skittle]

I've gotten in a little over my head when I decided to veneer a couple of small door panels with crotch veneer. I've done some veneering before with a vacuum bag but it was straight-grained, paper-backed veneer. This wavy and porous mahogony crotch is a different story all together. I've begun the flattening process with the spray from veneersupplies.com and I understand that I need a very particular type of glue, PPR. I have a small vacuum bag from Roarockit and am familiar with using it. 

I've browsed online quite a bit but can only find bits and pieces of helpful info so I'm hoping the great folks here can help me put it all together and provide the unwritten tips that I'm sure go along with using a veneer that's as difficult as it is beautiful.

[rwe2156]

I made this table of some pretty wavy stuff. Softened it with the product you bought.

I do not have a vac press so I glued it using hide glue and platens. I had a couple bubbles on the seam which responded beautifully to hot iron and re clamping.

There's some pretty prominent cracks I though the finish would fill. I should have grain filled it.

[mr_skittle]

There's some pretty prominent cracks I thought the finish would fill. I should have grain filled it.

Here's an idea that I haven't thought about! My veneer does have some cracks in it. There are some major ones at the margins but the ones in the usable field seem to close up nicely when the sheet is flattened.

[mr_skittle]

I'm still scouring the web and in need of some good advice.

https://woodweb.com/knowledge_base/Crotc...netry.html
I came across this forum that has some good info. The thread has lots of talk about "crossbanding" a second sheet of veneer at 90 degrees to the first. I was hoping to just glue my veneer to a panel of solid mahogany. I figured since they are the same wood, any seasonal changes would be similar on the veneer and the panel.

[rwe2156]

I'm still scouring the web and in need of some good advice.

https://woodweb.com/knowledge_base/Crotc...netry.html
I came across this forum that has some good info. The thread has lots of talk about "crossbanding" a second sheet of veneer at 90 degrees to the first. I was hoping to just glue my veneer to a panel of solid mahogany. I figured since they are the same wood, any seasonal changes would be similar on the veneer and the panel.

You need to get some cheap balance veneer and practice first.

Personally I wouldn't veneer to a large wood panel. Use a good quality plywood and be sure to veneer the underside (balance veneer).

Glue is a major consideration. Sometimes cracks or voids don't appear until after the glue is dried. That is b/c when the glue dries is tends to "pull" an any weakness or fissures will enlarge. On crotch or veneer prone to cracking you are going to get glue bleed through, so you don't want to use a glue that might interfere with finishing. For that reason I used hide glue (Old Brown Glue) on that table.

Another very good option is hot iron/PVA glue method. However, think about bleed through. Maybe cross-banding with a close grained veneer is a good idea. Maybe paper backed? You can also coat the glue surface with shellac to minimize bleed through.

[Dave Crow]

I put my vacuum press together from the info on joewoodworker.com and I have used all sorts of veneer over the last several years. I've had the best results when I follow the method used by Paul Schurch(schurchwoodwork.com). 

I had one particular nasty Madrone burl veneer that would have cracks show up days after I thought the panel was perfect!

Here is what I do. Make sure the veneer is dry after it is flat. Then, on the glue side, I fill the pores with wood putty(the type that is thinned with acetone) then sand with 400 grit. Next, spread the glue(I use a credit card) to a consistent thin coat. Place your veneer on the panel then, being sure the veneer slightly overlaps the panel. I leave the panel in the press for at least 24 hours.   

The most important thing is to be sure the veneer is dry after being flattened. After the panel face is veneered you can add veneer to the back.

I use Joe Woodworker cold-press glue but urea-formaldehyde is better. 

I will try to do some pictures showing examples.

Dave

[Dave Crow]

[attachment=38592][attachment=38590][attachment=38591]

Examples of veneer. The first photo is to show gloss finish on the top.

[mr_skittle]

First of all Dave, that's a beautiful piece. Greene and Greene inspired no doubt. I really like the side panel with the butterfly shape in the book-matched veneer.

Thanks so much for chiming in. I'm slowly getting it all together.

You need to get some cheap balance veneer and practice first.

Personally I wouldn't veneer to a large wood panel. Use a good quality plywood and be sure to veneer the underside (balance veneer).

How would you define a 'large panel'? my panels aren't too big. There are just a little over 12 x 12. My concern with using plywood is that it will be too thick by the time I get the veneer on, especially if I need to use 2 or 3 layers of veneer. Is there plywood thinner than 1/4 inch that is meant for veneering?

As far as glue goes, I have ordered some Ultra-cat PPR from veneersupplies.com, which is urea-formaldehyde. As far as I understand this is the only type of glue to use on crotch veneer, or at least mahogany crotch.

My understanding at this point is that I should put a layer of veneer on both sides of the panel. That shouldn't be a problem as the batch I got came with 5 sheets. One question I have is if I am supposed to also put a layer of veneer between the mahogany and the panel. I do have some paper-backed, curly maple veneer that I could use if it's necessary.

[Dave Crow]

Thank you for the kind comment.

Yes, Greene & Greene. The design was inspired by what I saw in the living/dining rooms on the "Woodnet" Group tour of the Gamble House in 2009. 

In my opinion, your 12" X 12" panel should not present any issues that would require cross banding. By sealing the glue side with wood putty thinned to the consistency light cream you reduce the chance of "bleed-through" and cracks. All of the panels I have made were either plywood or MDF, however the only problem I can think of if you use solid wood is not being able to glue the panel to the frame. As far as the panel thickness after adding the veneer to the front and back, I think you will find that if the frame groove is too tight, you can use a sanding block made with 220 grit sandpaper glued to a small piece of the plywood you used for the panel to slightly enlarge the groove. 

I look forward to seeing the completed project!

Dave

[mr_skittle]

Would be able to recommend a particular brand of filler that is thinned with acetone? I've not been able to find one in my area. Thanks for your advice on this veneer project. I'm hoping to get the panels glued up this week sometime.