Date: Thu, 26 Mar 2009 16:09:31 -0400
Reply-To: David Beierl <dbeierl@ATTGLOBAL.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: David Beierl <dbeierl@ATTGLOBAL.NET>
Subject: Re: Grill fix glue?
In-Reply-To: <vanagon%2009032614452272@GERRY.VANAGON.COM>
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At 02:45 PM 3/26/2009, Rob wrote:
>It's time to try and fix my '84 Vanagon grill, the lower grill has a
>couple of broken slats and I have the slats.
>Any recommendations on glue that works well for this type of plastic?
The Goop-goop may indeed work well, but there's not much surface area
and the plastic is pretty brittle by now. If you want a repair
that's as durable as the original I'd recommend to wash it well, wipe
the back with alcohol to degrease, scuff it well with extremely
coarse sandpaper, alcohol wipe again to get the dust off and lay on a
strip a couple inches long of glass cloth well saturated with
slow-curing epoxy (you'll know it's saturated when it's completely
transparent, no little opaque streaks). If you don't mind the repair
showing, mask the front and extend the preparation carefully onto it,
then use the same strip instead to wrap completely around the
break. That repair should be bulletproof, at least for microscopic
bullets. But the other should do well enough I think.
You'll need to splint it while it cures -- carve some styrofoam or
layers of cardboard glued together to match the curve, put a layer of
polyethylene (sandwich-bag material, polythene for the Brits) or
Saran wrap between it and the epoxy, and tie or tape it firmly on
each side of both breaks. The plastic will release cleanly when it's
fully cured, leaving a glossy surface (I suspect that if you bring
the repair to the front, the natural surface will be less conspicuous
than glossy, but if you want glossy that's how to get it). Keep your
epoxy-mixing surface nearby to test for cure.
Sounds like a lot of work, but it isn't really, once you get your
materials together. With slow-cure epoxy you should be able to prep
all the needed repairs and make your splints, then mix epoxy and
saturate all your strips of glass, then apply and splint each repair
within the 90-minute working time of the epoxy. Be absolutely sure
to err on the side of less hardener rather than more -- with too
little hardener it will cure slower, but with too much it will never
cure entirely hard, you'll be able to dent it with a fingernail. I
spent ten years struggling with epoxy before my dad taught me
this. The double-syringes make this easy if you press evenly and
then give a little extra press on the resin side at the end. The
resin is the thicker stuff, in case they're not marked, and the fact
that the hardener is thinner contributes to the problem, because it
flattens out and looks like less than it is.
You don't want filled epoxy like JB-Weld for this, it won't saturate
the cloth. But in a pinch a thick, thicker the better, lump of
filled epoxy extending well to either side of the break and faired in
at the ends should serve adequately. Or half a clean popsicle stick
instead of glass cloth, etc etc. The idea for a non-wraparound
repair is to get plenty of area to increase peel strength, then use
something that's tough and strong in tension; and try to arrange
things so that the glue bond will be stressed in shear as much as
possible, i.e. along the thin dimension rather than across it.
--
David Beierl - Providence RI USA -- http://pws.prserv.net/synergy/Vanagon/
'89 Po' White Star "Scamp"
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