Hi Alan I have no specific knowledge of that filler but for pinholes, I wouldn't use a filler but I'd stick with a primer. I have used a lot of US Paint's 545 primer for this. I mix up a batch unthinned and squeegee it on over the top of the surface. The thinner is forced into the holes but I also got to thinking that for my next project needing pinhole filling, I am going to try wiping it on with a rag then wiping the excess off with an acetone soaked rag. Having to spray the whole surface to fill a few holes then have to sand it all off is pretty heinous when you think that really, it is the pinholes you want to fill, not the 99.999% on the surface. I think the rags would work even better than the squeegee. You want to fill the pinholes before you prime, otherwise you will be sanding off virtually all of the primer and you'll have to do it again. My next comment is that
it isn't a good idea to ever put a polyester over an epoxy, be it filler or structural laminate. You might be OK but it just isn't worth the risk in my opinion. I would tend to stay with epoxy filler over epoxy substrate. Epoxy over polyester if the poly surface is well cured is normally no problem. But many people have tried using polyester gelcoat against a mold then laminating epoxy over the back of the gel. This can be OK but the real culprit is that polyesters are inhibited from curing in the presence of air. If you put a layer of polyester, isopthalic or vinylester over the back of a gel, it will bond well and essentially co-cure with the new laminate of the same family of chemicals. The problem is when epoxy is laid on top of the uncured surface of polyester, it never sets up on the inside of the wet gel therefore is essentially a gooey viscous liquid separation layer between them.
To solve this problem, some folks have had some success wiping off the uncured gel with MEK until they are down to cured gelcoat then laying up in epoxy. As you can imagine, this is risky and there can still be problems. For example you might separate the gel from the mold and you might not get all the uncured gel off. For these reasons, there are a few folks that have begun producing primers to interface between epoxy and polyester and visa versa. These have apparently worked well to a point but I wasn't able to get any of these folks to guarantee this for applications under the waterline of a boat. This tells me they don't trust it yet. Good luck and happy sanding! Dan Newland
"Alan K. Adamson" <aadamson@highrf.com> wrote: Ok, so I've
checked the archives, I've researched online, now I'm looking
for imperial information.
As it relates to body work. I've seen numerous posts on various composite
finishing sites about using some of the newer polyester based fillers. A
couple of examples. Evercoat makes a line of "RAGE" fillers that are
polyester based. The one most discussed is Rage or Rage Xtreme. The later
claims to be less at creating pinholes.
In the past, most have suggested that for *light* leveling, and filling when
doing body work, that you should *never* use one of these fillers. However,
I am curious. It seems that the composite body shops for cars use them,
also they are heavily used in metal body repair. So, why are they so bad
and has the technology changed enough that these would be ok to use and they
won't have the shrink, crack, etc issues of the older generation? I'm not
talking about "contouring issues", I'm mostly talking about thin
leveling
issues that you're trying to correct.
The discussion on primers was a good one, so I figure, I'll try it around
fillers?
Thanks in advance,
Alan
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