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Main Boards => The Bowyer's Bench => Topic started by: jtwalsh62 on June 16, 2011, 04:54:00 PM
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what causes air bubbles and don't tell me air got that much
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bubbles then:)
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uneven glue spreading.... one case I suspected perhaps old glue... lams or glass that aren't clean... irregular pressure from clamps or hose. Most likely spot is under the fade curves. You have to get those down firm and if the curve is sharp that can be a challenge. I redesigned the riser pattern for my longbows to provide gentler curves and that was a huge help.
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Cap'n Dick pretty well covered it.
Lee Hoots and I talked about this awhile back and agreed uneven glue was probably the most prob.
As if you have humps and low spots in the glue, the low spots trap air when you lay up the glass.
I spread glue with a scrap of lam to a thin even coat on both surfaces to be glued.
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I think using smooth on as opposed to the versamid will help too.
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You might also try using an old arrow shaft and roll a bead of smooth on along in front of the shaft as your laying down your glue. Works for me and is fairly fast in doing so...
FWIW
good luck
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I have heard if you slide the lams together from the side, it helps not getting bubbles.
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A hair dryer will bring up bubbles from the glue. I've been running a hair dryer over the surface. I'm not sure if it's bring out the problem bubbles or warming up the glue making it spread more evenly. Either way I have less problems.
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similar to the arrow shaft idea, I seem to have pretty good luck using a wallpaper trim roller. I like the idea of the hair drying. I keep a heat lamp over my glue blob, which probably does the same thing, but it's an interesting thing to try and I do have a hair dryer right at hand on the bench.
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One of the few times I got air bubbles was when I glued a bow up in a cold basement with cold glue.
Ever since, I try and heat the basement up well and warm the glue.
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At one time I covered table tops with a clear, thick epoxy mixture. Bubbles would appear out of nowhere in the 1/8" thick epoxy. I read the instructions and it told us to use a hair dryer to bring the bubbles up, it worked in that particular epoxy mix.
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I created this problem for myself when,after having already glued and stacked my lams,I separated the glass from the belly side,to adjust it,and laid it back down without smoothing the epoxy out.Won't do that again!!
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Heating up the lamb stack first will help alot and help with getting a better glue up.
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If your wood lams are a little green they could off gas causing bubbles. Oily woods seem to be the worst.