The FLAP store's spray can style thing is useless.  You would have to use
something more professional to make sure, it's good.  The best is to buy a
set of spray gun at Harbor Freight and then a pint of primer from an auto
paint store.  But I would paint it with POR 15 first anyway.
The only thing is wrong with the picture is, that you did not clean the rust
out from where it comes from.  Or at least you did not mention it.  Namely,
the kitchen unit has to be pulled out of it's place, take out the insulation
(which really is the culprit) and clean the area behind it, vacuum, then
paint it with POR 15, TWICE, then install non water absorbing
insulation, ---  and only then scratch out the seam sealer from between the
two panels on the outside of the van, wire wheel that area also before POR
15 painting, twice, and only then use the primer, etc.
You can use a masking tape all along the seam top and bottom to avoid over
painting and to have a boundary.
Don't rush this job, because the rust is working faster under the paint
incubated than if it's open.
Well, that's about all about this subject.  I do this often.  I'm in
Lynnwood, WA.
Zoltan

----- Original Message -----
From: "Florian Speier" <groups.florian@GMAIL.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Wednesday, October 14, 2009 2:32 PM
Subject: is primer/sealer weathertight?

>A few weeks ago I did my seams and surrounding three inches, at the typical
> rust spot where the camper stuff is welded in on the drivers side. I ran
> out
> of time after applying primer/sealer and thought thats ok to wait a while
> at
> this stage.......
> now we had two days of solid rain, and I have micro bubbles under the
> primer
> about an inch away from the seam, and worse, something slightly
> rustcolored
> at a few seam spots.
> Obviously I have to redo a few things, but I was wondering whether my
> assumption that primer sealer is weathertight was wrong, or if I did the
> whole thing wrong......
>
> thanks
> florian