Date:         Tue, 07 Nov 95 12:14 CST
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         EF0JPB1@mvs.cso.niu.edu
Subject:      Keeping Warm

>From: smitht@JUPITER.SUN.CSD.UNB.CA(Tim Smith)
>Subject: Re: Keeping Warm

>>Two problems come to mind with this approach.  First, making
>>sure the stuff stays in the bag.  Second, making sure it
>>doesn't *bow* the panels.  Your advice to do small spots,
>>move on, and come back after the first area cures does make
>>sense.

>Biggest problem with this is the likelihood of rusting out
>the body panels.  Trapping water/vapour between the foam and
>body panels is bad news. Any water accumulating near the
>edge of the foam will seep in, by freezing and expansion
>aided by panel flex and capillary action. Ziebart rust
>proofing fails this way as the guck hardens up and lifts off
>the surface. Good rustproofing sprays are non-hardening.

Bob and I have had some discussions on this off-list.  I
have problems with applying the foam directly to inside
metal and was proposing the baggy concept to keep insulation
"removable" for a variety of reasons.  No question that
retainage of water in those cavities is bad, wouldn't be
prudent, not gonna do it.

Certainly a rustproofing material (by any brand name) seals
the metal (for some length of time) and minimizes the
chances for rust.  My approach has been to clean, treat,
prime and paint the interior.  That way neither rustproofing
nor insulation needs to do that job.

>Regular fiberglass will pass vapour, hence the need for
>vapour barrier to keep it out of the area, summer heat
>drives the vapour back out however.  Any water leaks due to
>rust holes will guarantee more rust, especially since the
>area may be holding heat better and staying wetter most of
>the winter.

Fiberglass also holds water when it expands to fill the
cavity and settles to the bottom of the cavity.  That bottom
1/2 inch would seem to me to be the crucial point to keep
dry.  A spacer installed, before foam filling, which could
then be removed would keep air flow and drainage possible at
floor level.

Since 99% of us don't have A/C in an old bus, summer
conditions are not a major consideration as the temperature
inside will be close to the temperature outside.  The
problem is primarily a winter condition when trying to
retain heat in the bus.

>Any restoration work is hell with foam in place.  I'm
>sticking with FG, very cheap, light weight, easy to work,
>easy to throw away. Remember, aircraft are aluminium skinned
>and don't see much salt action. Foam is good there. My $0.02
>worth.

>Tim Smith

I agree that work after foam is difficult, hence my search
for removable foam.  Granted, removable is a term only
applicable to the cargo areas, since removing any foam from
the front doors would be nigh impossible.  Some of the
reasons you cite are the reasons I have settled on a
compromise:  foam rubber.  It can be squeezed into the areas
of the doors and still removed at a later date.  It does not
tend to sag or settle like fiberglass, so the air
space/drainage issue is resolved.

-Jim Bryant