On Fri, 16 Jan 2009 05:06:38 -0600, Jimw wrote:

On Thu, 15 Jan 2009 15:57:16 -0800 (PST), BobK207
wrote:

On Jan 15, 3:38*pm, Joe wrote:
On Jan 15, 1:53*pm, BobK207 wrote:

snip
I wood use Bondo for interior work without a second thought BUT I
would never use it again on exterior work. *YMMV.

Bondo works just fine on cars, even those that are used outdoors G

The stuff is a lot more $'s than Bondo.

Epoxy resins are simply more $$ than polyester resins. The
characteristic odor of uncured Bondo is from styrene, a reactive
diluent which makes the product even less $$. So buy whichever system
does what you really need.

Joe

Yes, Joe...Bondo works fine on cars......even those used outdoors,
just not cars made of redwood (what other woods?)

According the Bondo tech support, Bondo (at least the formulation sold
20 years ago) is not for use on redwood in exterior apps..... I wonder
if there are other species of wood for which Bondo is also "not
recommended".

The take away message from Bondo tech support was "Bondo is not good
for exterior use with redwood".

I extrapolated it to.....I don't risk using Bondo for exterior wood
repair.

Having experienced an exterior repair (of redwood) that failed, I
decided to not take that chance again......

So the only different between epoxy resin and polyester resin is cost?

cheers
Bob

Bondo does not last long on cars if used to repair rust holes. No
matter how well the rust is removed to bare metal, bondo HOLDS
MOISTURE. While the surface is painted, the rear of the bondo in the
hole is exposed, and absorbs water. Thus, it rusts away the metal
around it. I'd suspect that used on wood, it must be well sealed from
moisture or it will cause rot.

I used some JB Weld on a rotting spot in my wooden garage door. I dug
out the rot, and poured the JB weld in the hole. I applied another
coat later to form the surface. It's been a permanent and durable
patch, and I know it does not absorb water.

Jim

That i sexactly what happens. The bondo lasts maybe a year or two and
then falls out. You need an epoxy filler not a polyester filler like
bondo.

One such product that comes to mind is www.rotdoctor.com. Usually you
scrap out the rot and then use a watery "stabilizing" epoxy to
penetrate deeply and solidify any rotted wood fibers. Then you use the
putty like epoxy to fill the cavity.