air bubbles

[Sharp Shooter]

What causes air bubbles underneath the glass. I use a press with fire hose @ 65-70 PSI Sometimes I get bubbles and sometimes the limb is perfect, no bubbles. Could it be to much glue? Tony

[Lee Robinson .]

How are you applying it to the laminations?

[Sharp Shooter]

A 1" wide plastic puddy knife.

[kennym]

Hi Tony,

I rarely (not gonna say never)  get any bubbles.

I wonder if it is because I build longbows,and you make TD's? Maybe the bubbles have a bit more time to surface and are eliminated.

I use a wood scrap,like 1/8" x 3/4" x 10" for a spreader.

I'm sure your glue is not cold?

I've been told sliding the lams around a little on each other helps too, but I'm sayin if the air bubbles are in the stack, some of em are gonna stay there.

[Lee Robinson .]

Do you scrape it in pretty good or just swipe it gently? I put it on one way, and then go back the other way, and then back again...being sure to get it into the pores. I use firm pressure...not gentle and not hard. I have never had air bubbles on my high pressure form, which I use for my Protege Longbows. I did have bubbles once on a kid bow on a inexpensive form that I used "rubber bands" to glue it up, but I didn't use enough rubber straps IMO to put much pressure on it and I believe that was the cause. The bubbles in that kid bow were very minor though.

I would also suggest increasing your hose pressure.

[7 Lakes]

Try running a hair dryer over the glued  lamination.  It brings bubbles to the surface where they can be wiped off.

[kennym]

Good points guys.

Like Lee, I work it in pretty good.

[Sharp Shooter]

Thanks guys for your input, I'll try some of your suggestion on the next glue-up. Tony

[JamesV]

Also when you mix your smooth-on don't whip it just gentle stiring will help to keep bubbles out of the mix. Make sure both surfaces are covered with no dry spots and the glue is worked in. I probably use too much glue but I never have bubbles. When I use clear glass over expensive wood, I hold my breath while pulling the tape off the limbs, it seems to help.

James.....................