bonding core

[Flying Flivver]

Is using a lightly filled epoxy with colodial silica the proper way to bond new hd foam core to an existing glass laminate? They are both very close to flat panels.

[tunnels]

Originally Posted by Flying Flivver

Is using a lightly filled epoxy with colodial silica the proper way to bond new hd foam core to an existing glass laminate? They are both very close to flat panels.

No !!
Go find the proper stuff !!
Resin companies and core suppliers will have a product or can advise you what to use . Just resin and silica is not the answer. Of you have a failure its your problem and have no come back . silica only thickens the resin and makes it like toffee so where its thick its got little guts .
silica with glass micro fibres is a better mix but still needs to be made a little flexable so it has toughness !!
Go find information about CORE SHEAR !! , always use a foam density higher than you think you need !!! having seen foam core shear in test panels its scary !! also the glass peelability off foam is even more scary if you have a flexable panel or a panel that will flex a lot !!

[Herman]

Originally Posted by Flying Flivver

Is using a lightly filled epoxy with colodial silica the proper way to bond new hd foam core to an existing glass laminate? They are both very close to flat panels.

Is your laminate epoxy/glass? If so, you can use epoxy to glue the foam.

There are 2 things to watch:

-"neverbonds". Make sure your core is bonded for 100%. By far the best system is to vacuum perforated core, or scrimmed core if the curvature is large.

-adhesion. You should do a test to assess the amount of adhesion. You can improve the adhesion by "hotcoating" the core with plain (mixed) epoxy resin.

There is a very nice "ATC Core Bonding manual". Contact me if you want it. It is based on polyester based products, but there is a lot to learn.

2 more things:

The bondline thickness is totally dependant on the irregularity of the surface.

The glue is by far stronger than the foam, so that is the least of the worry.

[Flying Flivver]

Thanks Herman,

Yes it is epoxy/glass

I found the "ATC core bonding manual" on there website after you mentioned it.

ATC Core-Bond System, Core-Bond Manual©; Copyright 2006 by ATC Formulated Polymers Inc. Burlington, Ontario L7N 3H8

on a side note I have another question, I have a large roll of polyethelene vapour barrier used in house construction could it be used for vacuum bagging?

[Herman]

It could work well enough to ensure a good bond between core and laminate. It usually is slightly porous (the nature of PE) but nothing too dramatic.

[Flying Flivver]

thanks

[CatBuilder]

Just another voice, here.

Yes, using epoxy to make a repair of your core (with an epoxy laminate over the top) is not only one way of doing it, but it's the preferred way.

Second, the polyethylene tarp material will work for small vacuum bag jobs. Just be sure you have a good pump and be sure you look for holes in the polyethylene plastic before you even put it on the part. If you see no holes, I find it's usually air tight.

Depending on where you are affixing that polyethylene bag, you may also use Liquid Nails construction panel adhesive as a bag sealant. It's wonderful stuff. Keep it well away from the laminate (it tends to pull about an inch inward under the bag under vacuum). If you are using tape to seal the bag, use the real vacuum bagging tape. Not much else works well, other than the Liquid Nails.

One note of caution: Work neatly. I have a hard time with traditional vacuum bagging. I always get epoxy all over the sealing area and end up having trouble getting anything to stick and seal off the bag, as my tape slides all over the epoxy drips. Maybe some masking tape might help, but I've moved to infusion since bagging wet laminates is much more difficult.

[Flying Flivver]

I am a novice and curious about the infusion technique, you guys know where i could find some good information about it?