Replies

1. 
   SgianDubh | Aug 09, 2002 06:26am | #1

   Hot hide glue? Single veneer sheet, or a cross ply of some sort? Are you using just an iron, or an iron and a veneer hammer? How old is the glue in the pot you are using? What's the gram strength?

   The consistency of the glue applied described as 'syrup' is too thick for my taste. Hot hide glue-- if that's what you were using-- should run off the brush in a thin unbroken stream, not syrupy globs. You added a lot of water at the last minute, and it was cold by the sound of it, perhaps causing 'chilling' of the glue and stretching of the veneer. I only apply glue to the ground work, not to the veneer as well to prevent the veneer curling up and other odd reactions prior to application. The joint, from your description sounds either chilled or starved. You might be able to rectify the bubbles by slitting with the grain using a scalpel & co., injecting fresh hot hide glue, and hammering the excess out through the slit followed by taping.

   Most of this answer is designed to elicit more regarding your technique, tools, and methodology. Slainte, RJ.

   RJFurniture
1. 
   JEvans | Aug 10, 2002 04:15am | #2

   Thanks Sgain,

   I'm using Behlens dry ground hide glue (gram strength not on can) warmed in a glue pot. The glue is a new can and the batch was fresh. I was laying a single sheet of counter veneer crossgrain on the poplar using a veneer hammer. I used an iron on nylon setting to reheat glue under the applied veneer where I was having bonding problems.

   Rob Millard also said he only applies glue to the ground work but my being a rookie, I was reluctant and went by the books. It makes sense that applying glue to the veneer would add to potential swelling. I think I'll try applying it only to the ground work.  I sprayed water on the face of the veneer with a mist setting on a spray bottle.  The "books" say that should counter the moisture from the glue. What's your opinion on that?

   Any advice is appreciated. My only source for learning is from books, magazines and by the contributions of experienced woodworkers who post here.

   Thanks,

        Jeff

1. 
   SgianDubh | Aug 11, 2002 12:02pm | #4

   Jeff, I think Rob largely provided a similar answer to the one I was about to post. His techniques-- from his description here and elsewhere, seem rather similar to mine. Addressing your question on adding spritzeed on water. For me, in an ideal world, I prefer to add no water to the show face to reduce stretching. However, in practice, water sometimes has to be used in the laying process, and sometimes water (and other substances) are used to flatten particularly contrary veneers prior to the actual hammer veneering job. Water often gets involved in the job, but I prefer it if it doesn't. Now, if you move to applying the glue to the groundwork only, I'd avoid spritzing the veneer altogether until you start to see how the job is going-- dampening one face with this 'gluing groundwork only' method leads to the veneer curling up which can make it awkward to lay. But as before, you may find that you need to steam in some water somewhere in the process.

   Apart from Rob's tricks with brass shim stock, etc., don't forget my earlier tip of slitting with scalpels and injecting more glue to flatten bubbles. Here you'll often need an iron and water, perhaps from a damp rag to soften the veneer and get the bubble down, especially if you're fixing a bubble the day after the veneering job.  In dark species especially, slits and the like are near enough invisible once the job is complete. They are more likely to show in white veneers, e.g., European sycamore or maple, especially if done clumsily.

   I didn't see you once mention using a veneer hammer, but I presume you are using one as well as an iron? I'm not familiar with the Behlens hide glue, so I can't comment. Slainte, RJ.

   RJFurniture

   Edited 8/11/2002 5:06:50 AM ET by Sgian Dubh

2. 
   RLMillard | Aug 11, 2002 04:06am | #3

   Jeff,

   I think your problem might stem from sanding your substrate, because that would make a more porous surface, and the glue may have soaked in too much. Although, I also believe, as noted above, that your glue may have been too thick, which would have compensated for the porous substrate (I’m talking out of both sides of my mouth). One thing I have come to rely on is to give the substrate a coat of thinned down glue at least the day before I plan on hammer veneering. Hide glue bonds well to itself, and this sizing will prevent or at least go a long ways toward helping prevent a glue-starved joint. The other thing you might try is to just let the problem areas sit for about a quarter to a half-hour, and reheat them and have at it with the hammer. This allows the glue to thicken up a bit and therefore grab better. When re-heating these areas, make sure your iron is set for a very low heat, just enough to liquefy the glue, or you’ll just be back to where you started. One other thing I do is I have lead weights and a piece of brass shim stock handy when hammer veneering large sheets. What I do is heat the shim stock and place it over the problem area and then stack the weights on it. Don’t let this sit for too long, (just until the glue has gelled maybe 10 minutes at the most in normal temperatures) as hide glue bonds quite well to brass. I normally have very little trouble with mahogany veneer, with respect to bubbles. I recently learned a lesson in hammer veneering, when making a Federal card table. For reasons of historical accuracy (or the appearance of historical accuracy) I used poplar veneer for the counter veneer. This veneer wound up hopelessly wrinkled, after going down very nicely. I fixed it by heating the whole sheet and then lifting it and re-laying it. While re-laying it, I adhered one edge the full length of the top, and then I continued laying the veneer in a row like fashion until the whole sheet was laid. By doing it this way, I prevented bubbles from getting trapped, but it wasn’t easy. The standard approach is to lay the sheet into the gelled glue and then heat and work from the center towards the edges, but this failed completely with the poplar veneer. I finally decided that the nearly 90 degree room temperature did not allow the glue to gel sufficiently to hold the less than stable poplar in place. It is actually easier to hammer veneer in cool weather, since the glue seems to gel faster. It helped when I pointed the One other piece of advice is to add a little white vinegar to your glue. I don’t know why, and I have no hard evidence to prove it, but this seems to help the glue grab better. It is better to have too little vinegar than too much. I don’t measure my gluing materials, but I guess I add about a teaspoon to 8 ounces of glue. My best advice, is to keep trying, hammer veneering is a skill worth acquiring, I can’t think of a more versatile or rapid way to veneer in a small shop.

3. 
   RLMillard | Aug 11, 2002 02:31pm | #5

   Jeff,

   As usual Slainte has provided more concise information, than I do with my rambling "style". I missed your point about the quality of the glue that you use, but the Behlen glue is not the problem, as it is top quality glue. I started out using it, but it is so expensive that I switched to the ground hide glue from Olde Mill Cabinet Shoppe (www. oldemill.com), since their glue is equally good but only $18.00 for 5 pounds. On slitting the veneer bubbles, I have done this, and have been very happy with the results, but I have found it is a little tricky. Many times, unless the bubble is small, when it is forced to lie flat the edges of the slit overlap. This forces you to do some very careful surgery. I’ve found by that by working along the edge that ends up on top, and angling the knife so the handle leans away from that piece; I can achieve a nearly invisible seam in dark woods. It also helps to make your initial cut along a prominent grain line. In light color wood, I read but did not believe until I tried it, that rubbing chalk on the cut will help disguise it. I still don’t understand why or how it works but it does. That little tidbit and many others came from Ernest Joyce’s The Encyclopedia of Furniture Making, which is a great book.

4. 
   Phil_Twiss | Aug 11, 2002 05:49pm | #6

   Hi Jeff

   Here's another little trick that can help with nasty little bubbles.  I have used this with particularly tricky bubbles that just won't stay down, usually as a last resort.

   Do the usual thing with slitting and injecting hot glue into the bubble and use your hammer to remove excess, making sure there are no big gobs of glue under the veneer.  Then using heated cauls (flat smooth blocks of wood) which are really only just hot to the touch (I have a hot plate) clamp them on to the surface over the bubble with a couple of sheets of paper between (greaseproof paper works pretty well).  Leave them as long as it takes for the blocks to cool and when you remove them the bubble should be no more.

   Just a couple of points to note:

   1. The cauls should be planed or finely sanded otherwise marks in their surface will telegraph through to your veneer.  I have successfully fixed bubbles in finished veneers with no major problem.

   2. Chamfer or ease the edges of the cauls.

   3. Clamp FLAT but not too hard.  Sometimes on wide surfaces you need to use pins to hold the cauls in place, usually the pin holes are almost invisible.  Sometimes you just need to get creative with your clamping (go bars, wedges, etc)

   4. Always use paper between cauls and veneer, two sheets is best otherwise you will have the fun of trying to extract the block from the top.

   5. Remember, the smokey smell is probably the caul you left on the hotplate, its never happened to me but I once met a bloke who did ;-/. Honest........

   I'm sure there are other things in this that I have missed as I am by no means an expert, but all these things help.

   Cheers

   Phil

1. 
   JEvans | Aug 12, 2002 02:22am | #7

   Thanks everyone for the advice.  Between having to earn a living (obviously not at woodworking) and yard work at home, it will be few days before I can attack my project again.

   Jeff

1. 
   Shepherd1800 | Aug 12, 2002 04:06am | #8

   Jeff,

   All of the advise above is good, if you use a heated iron to refasten the blisters, slitting and injecting more glue, you might try a thick large piece of plastic (lexan, etc.) with the edges slightly rounded, as a clamping block to insure that the blisters are pressed down flat.  The clear plastic allows you to 'see' if the work has gone back flat and the glue will not stick to the plastic.  Good Luck

   Stephen Shepherd

   [email protected]