At 05:28 AM 6/7/98 -0500, you wrote:
>Oh NO!!! Not "Air Bubbles" again!
>
>Actually, I just wanted to provide a little bit of closure on this subject
>which came up a few weeks ago, by posting some photos as I promised.
>They are at http://home.echo-on.net/~jpolenek/airbubbles.html
>
>Just to re-cap for anybody who's new, I had noticed what appeared to be
>voids under the fibreglass of my first bulkhead. It was suggested that this
>may be surface contamination (e.g. from handling) of the urethane foam and
>that it should be prepared by sanding then applying a micro slurry before
>glassing. I tried this and it's great! I used this method on my Wing Lift
>Bulkhead with excellent results. It takes me about twice as long to do a
>lay-up because I spend a lot of time making sure the slurry job is thorough,
>but the improvement in appearance and peel strength is well worth the extra
>time.
>Thanks for everybody's input.
>
>Joe
I looked at the pictures. It appears to me that you could eliminate the
bubbles by applying just a thin layer of epoxy (without microballoons) onto
the foam first, then lay the cloth over it.
On the other hand, those little bubbles don't look like much of a problem
to me. They aren't a classic delamination where you have to worry that
several inches of area are now weakened. The foam is still intact, it's
just not bonded to the fiberglass. I don't think little bubbles like that
would produce any more tension or compression failures than if the glass
were bonded directly to the foam. I would think that the area is small
enough that it won't matter much. Just my opinion. What do the composite
experts here say about it?
Dave Morris
-----------------------------------------------------------------------------
dragonlist is hosted courtesy of Interstice Inc., a provider of reasonably
priced virtual domain hosting for the world, and dedicated circuit and
dialup for Silicon Valley. http://www.interstice.com (408) 369-4490
