Glass delaminating issues

[macbow]

If you want to get a higher temp on the set up without a box.
I put two shielded 100 watt light bulbs on my table next to the form. Cover with a wire basket and add a sleeping bag over everything.
Works well over night.

[snapper1d]

120 grit is what is recommended by SmoothOn.They test their products more than we do so I would go with what they recommend.

[JamesV]

I have worked with epoxies for over 30 years and have found that mixing ratios are not that critical. I don't wipe my lams or glass before glue up with anything and never have a problem. Maybe I am just lucky. I would certainly like to know where your problem is if anyone has the answer.

James

[JamesV]

With over 30 years experience using epoxies I have found that the mixing ratios are not that critical. I don't wipe my glass or lams with anything prior to clue-up and never have a problem, Maybe I am just lucky. I would certainly be interested in a solution to your problem if anyone has the answer.

James

[djschwartz90]

Thank you guys for all your comments, so much to consider! With so much variation in sanding and general prep techniques, I think that I'm going to  do some test glue ups using different prep/sanding and clamp pressure variations to see if I can determine what is causing my problems. I'll be sure to post my findings for anyone who is interested.

[macbow]

Jd, if you have some scrap left try some experimenting.
One glued like normal one where you use some heat like a light bulb.
You could also test the surfaces with different sandpaper.

I'm guessing glue it self or not enough heat.
You should have to grind the glass off no peeling.

[bamboo]

http://www.smooth-on.com/tb/files/EA40.pdf

[Mike Mecredy]

100 grit is wrong for grinding laminations, use 40 grit on your drum sander.

[Troy D. Breeding]

I don't use anything less than 40grit on my veneers and sometimes use 36 grit when grinding core material.

The only problem I ever had when building a bow was the one time I wiped my glass and veneers down with denatured alcohol. Didn't de-lam, but had some blotchy spots show up between the glass and veneer. I simply brush the veneers, core lams, and rough side of the glass clean of any loose pieces with a fine wire brush. That brush is never used for anything else.

I haven't built as many bows as some, but that was my only failure in the glue/joint department in over 100 bows.

[7 Lakes]

Something's wrong with your glue, I don't know what "thickened" means for epoxy.  Even if it was starved under each clamp.. between clamps would be fine.  Finger oil on glass or wood... unless you rubbed wood and glass though your hair there would be some spots the glue worked.  Toss that glue and get some EA:40 Smooth On.

[7 Lakes]

100 grit is to fine, I didn't notice you mentioned this before.  Back down to 60 as the smoothest, 40grit is even better.  I still don't think this is your whole problem, maybe the fades where the pressure is the greatest but you have a glue problem, replace it.

[Tim Finley]

After it has pulled apart is the glue residue stuck to the wood or the glass? I have been building bows commercially for 30 years, I always wash every gluing surface with acetone it does not bring up the oils it washes them off the surface and forces them down. Blow off your surfaces, brush them off ,then take a clean white cotton cloth soaked in acetone and see what you have you'll be surprised what residue is still there.
  I grind all my lambs with 36 grit and my veneers are ground one side 36 and the side to the glass up to 150 I know some bowyers that grind veneers 220 grit, it makes the wood grain come out better with a smoother grind and we have had no problems.
  Smooth on should be heated most epoxys are stronger if heated.
  I've said before you can take any bow apart with a butter knife . Once the glass starts stipping you can remove it pretty easily....Tim

[djschwartz90]

Tim- It's hard to tell, but I would have to say there appears to be more glue stuck to the glass than the wood. And yes, your last point is what I am really questioning - none of the bows I have built have failed or delaminated while shooting, but I am questioning whether or not the glass should be able to be stripped off of the bow with just a razor blade. So you are saying that once you start peeling the glass with a knife or something, it is normal for it to be able to be stripped off relatively easily?

[Tim Finley]

I think it does I have played with some broken bows and lifted the glass and it came off pretty easy but usally the glue was more on the wood than the glass . I have some old limbs laying around I,ll experiment....Tim

[mater]

I use 80 grit all the time. I think your wood has to much moisture. Water comes out when heated and gets trapped under glass causing problem. Ive had this problem in the past.