Bubbles in glue

[AndyTurner]

Hi, i'm using EA-40. 1:1 mix. Heating to 65 deg C for 6 hours. All as per instuctions.
I've noticed that lots of little bubbles are appearing in the glue.
Is this normal?
Thanks,
Andy

[Stick Bender]

A couple of probable causes are insufficient or un even clamp pressure  or lifting and resetting the lams can cause bubbles  but I have never seen bubbles in the glue line what clamping method did you use ?

[AndyTurner]

Hi SB. Thank you for getting back.
Its not on the glue line. I haven't sanded that back yet. Its on the edges of the bow which need to be cleaned off anyway. See attached. My concern is that if between the lams, where you can't see, there are bubbles, this may structurally compromise the bond between the core and backing. In my head there should be no bubbles in the glue. Clamping method attached!

Regards,
Andy

[willie]

I can't help much with the glue bubbles, as I have never used EA-40, but if your glue up experiences problems, you might consider more clamps or different pads on the next one.

BTW, my grandson grabbed my organic vapor mask to use at the grocery store for the anti-virus thing. It sure kept the other shoppers at a fair distance, but next time he will want the mask and the headlamps after seeing that pic.

[AndyTurner]

 
...not just head lamps - bionic vision. Jewellers specs, up to X25 magnification!!!! Really good bit of kit at my age!

I'm not worried about glue lines. Its just the fact that there are bubbles in the waste product. If they are there then they probably exist between the lams where you can't see.

Regards,
Andy

[Stick Bender]

With your clamp set up it is probably the issue when I do a boo glue up using clamps I use pressure strips and clamps spaced evenly about 1" a part epoxy needs good solid even pressure some guys around here have good luck with intertube rubber strips and the wrap method , I personal only use the fire hose method now but it requires building a form ,what ever method the goal is the same solid even presure across the whole limb !

[AndyTurner]

Hi, Sorry but it's got nothing to do with clamps. I'm just looking at the "unclamped" waste product. Why does it have bubbles in it? Do other people see bubbles in the waste glue that ozzes out? Thanks, Andy

[willie]

Andy,
 I was not inferring your clamp set up may have caused the bubbles. My comment about the clamps, and possibly sticks also, was a general observation about laminating with epoxy.

Stick, what thickness and length pressure strips do you use? Or at least recommend for someone that may not have enough clamps to go 1 per inch? Seems like a guy could get by with less than 65 clamps.

[Stick Bender]

Willie I use 7/64 aluminum strips for the outer presure strips but put rubber strips on the belly & back the rubber keeps even presure around the nodes it does require a lot of clamps but get them on sale at Harbor Frieght EA-40 is a thicker epoxy & will get bubbles trapped if uneven or to little of presure ,bubbles should not be there, there a indication air is in the joint for what ever reason !

[willie]

Thanks  Stick.
BTW, Andys glue has little bubbles forming on the ipe also.. If they came out of the joint, then they must have flowed up hill somehow.....

[bownarra]

I've used many tubs of EA40  - those bubbles are not a problem. Carry on!
Your problem is lack of even clamping pressure with that set-up.
You should either wrap with inner tube. Use a clamp every 3 inches or go the fire-hose method.

[Stick Bender]

He mentioned he hot boxed or heated his bow Willie making the epoxy thinner the bubbles probably flowed up the only other thing that I can think of is unless the epoxy is to old ,Im not saying your going to get a delam ,Im just saying there not there under a properly done glue up !

[Stick Bender]

Andy here is another trick for preventing it on future bows when you get the lams together never lift them off for adjustment when in place add zip ties to hold every thing in place as not to shift them when the clamps are applied you can cut them off after clamps or if using pressure strips thicker then .030 you can leave them in place it works great , if hot boxing allow the bow to cool for hours before removing another thing you can do is preheat your cans of Ea-40 to 100 Deg before mixing it allows the epoxy to flow better I think one off the reasons every bodys talking more clamps is if not enough clamps you can cause see sawing in the lams making them suck in air with pre heating the epoxy it allows the air to flow out more easely & applying clamp presure of 40-75 psi , I use a fire hose easy to get there but I have frinds that use clamps changing the clamp heads to hex bolts & use a torque wrench for proper clamp presure even easier & cheaper is the rubber bands ! Im not saying any of that is the end all method just trying to help to prevent future issues !

[AndyTurner]

Good morning chaps. Sorry I went to bed last night. I was shattered!

Thank you for all your input. There are some really interesting things to think about.

The EA-40 is only a few weeks old.

On my first glue up I used 2:1. A thicker mix. The glue lines were spot on and I only used a couple of clamps.
I went 1:1 after I read that the bow would last longer because the mix was more flexible. The second glue up, 1:1, was disaster in terms of glue lines. This third glue up, 1:1, remains to be seen.

I like the zip tie idea. I used insulation tape on the second one and duct tape on the third. Both worked well.

I'll get on and clean it up today, come back with some pics and you can all critique me! :0)

Have a great day & thanks again,
Andy

[Stick Bender]

The Zip tie method is not my own ,Big Bob from Australia turned me on to it , below is a pic of one of the open top fire hose forms I have many in different shapes there easy to make and can be made in a couple of hours they use mule tape to secure the fire hose there very versital and can be made in any shape ,Im curently making one for a composite horn bow , there quicker & easier to use then clamp method and for natural bows ,dimensional lumber can be used good luck looking forward to your progress !