If you sand the old finish down to the epoxy primer
this is true.
If you have sprayed the epoxy within the previous 24
hours (prior to it really hardening), this may be
true.
If you sprayed the epoxy on 6 months ago and let it
sit, you should abrade it first with sandpaper or
Scotchbrite (TM) pads prior to painting over it.
Also, to get the best adhesion from primer, bondo,
etc., you should acid etch bare metal prior to
painting. This will remove all the surface
contamination and properly prepare the surface.
Most stripping methods leave some level of
contaminants. It may be enough to cause fisheye or
pinholing in the primer, or it may just reduce
adhesion...but by how much? 2% or 95%???? Maybe you'll
be lucky, maybe not.
Your pneumatic sander can spread oil on the surface
(not to mention oil from your compressor or in your
hose that can also affect the paint spraying from your
gun), chemical stripping can leave residue, media
blasting can spread contamination, etc.
Frequently, solvent wiping only dilutes contaminants
and smears them around.
I'm not trying to spread fear, but many things can
screw up a paint job besides runs and sags...
My recommendations:
Acid etch bare metal before priming.
Use a good quality alkaline wash prior to applying
fresh paint over old paint.
Use good quality materials (like 3M brand masking tape
rather than el-cheapo masking tape).
BK
--- chance wolf <timberwolf@wheeldog.net> wrote:
> I remember something from "Army Motors" that I'd
> read some years back which
> stated that among the various benefits of epoxy
> primer was the added bonus
> that body fillers (Bondo, White Lightning, etc.)
> would adhere to the primer
> as they would bare metal, avoiding the need to grind
> and wire-wheel back
> down to bare metal.
>
> Does anyone know if the above holds true in
> practice? It'd sure make my job
> a lot easier.
>
> Andy Hill
> MVPA 9211
> Vancouver, B.C.
>
>
>
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This archive was generated by hypermail 2b29 : Tue May 01 2001 - 07:42:42 PDT