Frets developing under clear glass?

[PV]

Howdy boys,
Been a while.Got my tools out of storage and in the process of setting up my shop. Haven't ground a lam in 4 years.
Before I shut it down I had a couple of bows develop what looked like frets on a wood bows belly under the back glass after shooting in.
Anyone else have this problem?

[bamboo]

I've seen bacote do that

[BenBow]

I had padauk veneers do that

[PV]

Mine have been with lacewood and zebra.I read somewhere that epoxy degrades in metal containers. Are  you guy's using Smooth on ?

[bamboo]

Are  you guy's using Smooth on ? [/QB]

yes to the smooth on--I use a  2a-1b ratio also

but the bacote bow I saw the failures with --I did not build
  my buddy made it sound to me as if it was oily wood blemishes under the glass--when I got looking at it-- there were tiny fractures under each bubble-reminded me of frets--but were on the tension side under the glass

[Pheonixarcher]

I had a set of limbs do this with walnut veneers. I've discussed the problem with several prominent bowyers, and the consensus was one of or a combination of the following:
  -over inflation of the air hose (or over tightening of clamps) causing too much squeeze out or a starved glue joint.
  -cooking the limbs with too high of heat possibly causing the epoxy to "boil" or create small gas bubbles leading to voids under the glass.
  -moisture levels. Either too high at glue up and cooking the limb caused that moisture to try and leave the limb, again causing voids under the glass. Or too low at glue up and not getting the limbs sealed and finished soon enough, causing them to take on moisture and swell a bit causing the glue bond to break under tension.

 

 

[Dmaxshawn]

Yes Paul is back I cant wait to see what comes out of this shop.  Its been a while your work is awesome.  

I've had that same problem on a couple in the past I had it narrowed down to wet veneers I had backed off the pressure on hose to 50 because the heat makes the pressure increase.  

Shawn

[Stagmitis]

Hey Phoenixarcher, that`s an awesome post and pretty much covers all the mistakes that can be made and that I have made!  

Since then, I have ditched heat strips in lieu of a heatbox, (unpredictable,difficult to maintain desired temp uniformly), went to clamps vs hose (more control), and  maintain an 8% moisture level in my materials.

[PV]

Thanks for the replies gentlemen. The bow pic's you posted Paul are exactly the trouble I had. My quandary with them is they show up months and sometimes years after the bow was built. Much like some of my wooden bows.
I'll try some of the things suggested and see how they turn out.
Good to see your still here Shawn!
On another subject what are you guys using for a pic hosting site for posting? Can't seem to access my Photobucket account.

[Pheonixarcher]

Well thanks for the kind words gentleman. I hope that information can help everyone.

Shawn, I appreciate your enthusiasm. I'm really itching to finish a bow. Lol. I laid up a riser block months ago, but I've been playing with my limb design, trying to make improvements. After many stack formulas and form alterations, I've concluded that that profile just isn't going to do what I want it to. So I've laid up some new form blanks, and am starting from scratch. Hopefully I won't have to make too many adjustments, and will be able to complete a bow before too long. Lol

PV, I just had to re-set my password for photobucket, as it wouldn't let me in either. But it seems to working for me, although it is slow to upload photos.