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Thread: Laminating "Thick" Veneer - Do I Need to Vacuum Bag?

  1. #31
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    Quote Originally Posted by John TenEyck View Post
    The problem with his product is it's really coarse and stiff, and if you get a wrinkle in it it's impossible to get rid of. The window screen mesh is much more compliant, available locally, and cheaper.

    John
    My wife refuses to iron anything, so I commandeered the family iron for my workshop. I use it mostly for hot-melt edging, but set at moderate heat it also serves to smooth wrinkles in breather mesh.
    -- Jim

    Use the right tool for the job.

  2. #32
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    Bill, if you put the mesh outside of the platen it will equalize the pressure on the platen, but do nothing to equalize the pressure on the veneer, glue, substrate interface. If the veneer and substrate are of constant thickness, it's all good. However, the veneer and substrate often are not perfectly flat and, if they aren't, you will have areas that could see low or even no pressure. But if you put the mesh directly outside the veneer every square mm will see the same pressure and the bond will be good as long as the glue was sufficient and well distributed. Yes, if the substrate or veneer has thin spots there will be thin spots after it comes out of the bag. But I'd rather deal with that than areas with poor/no bond.

    John

  3. #33
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    Quote Originally Posted by John TenEyck View Post
    But if you put the mesh directly outside the veneer every square mm will see the same pressure and the bond will be good as long as the glue was sufficient and well distributed.
    Interesting point. In a nutshell, the substrate on top of the veneer would dilute the pressure of the bagging. Taking that to the extreme .. sometimes (often) I veneer both sides of a substrate (panel) at once. One has the benefit of being just beneath the breather the other is pressed against the platen, which we're saying is "less effective." Presented with that task would you do two glue-ups?
    "the mechanic that would perfect his work must first sharpen his tools.” Confucius

  4. #34
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    Quote Originally Posted by John TenEyck View Post
    You will be happy you got a vacuum bag set up. Flat work, curved work, it can do it all.

    I'm glad you saw that comment by Joe W. with regards to PPR glue. I had a very bad experience with his Cold press glue with 1/16" thick shop sawn veneer. Total disaster actually; I'll never use that stuff again on shop sawn veneer.

    I like Weldwood Plastic resin glue (PRG) for shop sawn veneer. 1/16" for most interior work, 1/8" for interior door skins, and 3/16" for exterior door skins. If you read the literature for that product you want a lot of pressure to affect a good bond and minimum glue line at the recommended coverage. A few hand clamps around the edges of a large panel won't do it. Cauls might get you there, but the vacuum bag is a far better and easier approach, even though the absolute pressure is less than Weldwood recommends. For hand clamping epoxy is a far better approach because you don't need, nor really want, high pressure. Epoxy works great in the vacuum bag, too, and I would probably use it exclusively if the cost were not high compared to PRG.

    One last tip. If you have to make up edge seamed panels of shop sawn veneer, glue the edges before gluing them down to your substrate. That will prevent any unwanted opening of those seams. Learned that one the hard way. TB III works fine for that.

    John
    Thanks for writing this, though certainly a bit frustrating to read after the fact. That said I have used it on multiple shop sawn veneer projects without issue thus far even with wide flatsawn panels.

    I typically glue them thick then plane them thin. Still, I will heed your advice as it is always on point.
    Bumbling forward into the unknown.

  5. #35
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    Quote Originally Posted by Bill Adamsen View Post
    Interesting point. In a nutshell, the substrate on top of the veneer would dilute the pressure of the bagging. Taking that to the extreme .. sometimes (often) I veneer both sides of a substrate (panel) at once. One has the benefit of being just beneath the breather the other is pressed against the platen, which we're saying is "less effective." Presented with that task would you do two glue-ups?
    Not sure I understand your question. I try to veneer both sides at the same time whenever possible. Sometimes I stack up two or three veneered substrates with mesh in between. And often I use no caul at all. If your bench is flat it isn't needed. Hopefully, some of that is relevant.

    John

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