Coloring epoxy
 

I have several places on my boat where the gelcoat has come off from
pulling it up on the beach and I was going to use epoxy to repair. I
have a gelcoat repair kit that has several color tubes and I was
wondering if I could use these color tubes to tint the epoxy. I have
seen epoxy pigment but could not find any in town and need to finish
the repair tomorrow. Any advise would be greatly appreciated.

Kevin

On Thu, 09 Jun 2005 18:51:36 -0700, kscarter wrote:

I have several places on my boat where the gelcoat has come off from
pulling it up on the beach and I was going to use epoxy to repair. I
have a gelcoat repair kit that has several color tubes and I was
wondering if I could use these color tubes to tint the epoxy. I have
seen epoxy pigment but could not find any in town and need to finish
the repair tomorrow. Any advise would be greatly appreciated.

Kevin

Kevin,

I'm not an expert on this topic, but since you need an answer in a hurry,
I'll offer my $0.02.

I'm unclear on whether the tube is just inert pigment, or whether it is
uncatalyzed polyester resin with pigment in it.

If it is polyester resin (and I think it probably is), I don't think you
can mix it with epoxy. If it is pigment only, it MIGHT work. You could try
a small test batch to see.

Does the gelcoat repair kit come with catalyst? Maybe it would just be
easier to use the gelcoat repair kit and forget about epoxy.

Or, forget about the pigment. Just use epoxy (with some kind of sandable
filler) and then paint over it. By itself, epoxy is a terrible way to
repair gelcoat, since it doesn't build up fast enough, and it is
moderately difficult to sand, and it is kind of expensive.

--Mac

Mac wrote:
On Thu, 09 Jun 2005 18:51:36 -0700, kscarter wrote:


I have several places on my boat where the gelcoat has come off from
pulling it up on the beach and I was going to use epoxy to repair. I
have a gelcoat repair kit that has several color tubes and I was
wondering if I could use these color tubes to tint the epoxy. I have
seen epoxy pigment but could not find any in town and need to finish
the repair tomorrow. Any advise would be greatly appreciated.

Kevin


Kevin,

I'm not an expert on this topic, but since you need an answer in a hurry,
I'll offer my $0.02.

I'm unclear on whether the tube is just inert pigment, or whether it is
uncatalyzed polyester resin with pigment in it.

If it is polyester resin (and I think it probably is), I don't think you
can mix it with epoxy. If it is pigment only, it MIGHT work. You could try
a small test batch to see.

Does the gelcoat repair kit come with catalyst? Maybe it would just be
easier to use the gelcoat repair kit and forget about epoxy.

Or, forget about the pigment. Just use epoxy (with some kind of sandable
filler) and then paint over it. By itself, epoxy is a terrible way to
repair gelcoat, since it doesn't build up fast enough, and it is
moderately difficult to sand, and it is kind of expensive.

Actually, the coloring kits contain universal pigments that can be used
with any resin and I've used them successfully with epoxy. I've also
compared West Systems white tint with white tint sold for polyester
resin and it's the same product. I simple way to tell is to smell them.
The odor of polyester resin is unmistakable, but the tints smell more
like latex paint than anything else. Also, if they were polyester resin,
they would eventually harden in their tubes, as polyester has a limited
shelf life.

I have colored epoxy using artists oil colors. Any art supply store has
hundreds of colors available. The colored epoxy handles and finishes
exactly like neutral epoxy.
Dave

"Dave W" wrote in message
...
I have colored epoxy using artists oil colors. Any art supply store has
hundreds of colors available. The colored epoxy handles and finishes
exactly like neutral epoxy.
Dave

How dark (dense) have you tinted to?
Dark enough to cover other colors already present?
Would this give some degree of UV protection?
thanks



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Yes, epoxy can be tinted, but that doesn't completely solve epoxy's
deterioration in sunlight. I'd use tinted epoxy only in places where the
sun don't shine, like in lockers & lazarettes, and under a paint finish.
"Just Us" wrote in message
...

"Dave W" wrote in message
...
I have colored epoxy using artists oil colors. Any art supply store has
hundreds of colors available. The colored epoxy handles and finishes
exactly like neutral epoxy.
Dave

How dark (dense) have you tinted to?
Dark enough to cover other colors already present?
Would this give some degree of UV protection?
thanks



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I don't know about the degree of UV protection offered by tinting. In terms
of how dark can one tint, I have added black color to make the epoxy as dark
as ebony. By the way, I have had a test sample of epoxy and fiberglass
scarfed plywood in the bed of my truck for four years with no apparent loss
in strength of the joint. The (clear) epoxy has yellowed a bit but the joint
seems to be very strong.
Dave

System Three says that no pigment or filler provides adequate UV protection.
The UV will break down the outer layers first, and depending on which filler
and how densely it was added, the UV will penetrate further too. The joint
(below) is protected from UV by the wood. Best idea for epoxy coatings is
to add a UV coating on the outside. And even with that, if it's a clear
coat then the UV inhibitors do get used up and the clear coat itself needs
renewing now and then. Paint or gelcoat is better.

Brian


"Dave W" wrote in message
...
I don't know about the degree of UV protection offered by tinting. In
terms of how dark can one tint, I have added black color to make the epoxy
as dark as ebony. By the way, I have had a test sample of epoxy and
fiberglass scarfed plywood in the bed of my truck for four years with no
apparent loss in strength of the joint. The (clear) epoxy has yellowed a
bit but the joint seems to be very strong.
Dave

If the strength of the epoxy is important, do NOT color it dark, at least
not if it will be in the sun. Dark colors get hotter and the epoxy loses
significant strength at even mildly elevated temperatures.

Military uses; e.g. fighter aircraft skin, involve epoxy that is oven cured
to withstand higher temperatures -- a touchy process and a major investment.

Roger

http://home.earthlink.net/~derbyrm

"Dave W" wrote in message
...
I don't know about the degree of UV protection offered by tinting. In
terms of how dark can one tint, I have added black color to make the epoxy
as dark as ebony. By the way, I have had a test sample of epoxy and
fiberglass scarfed plywood in the bed of my truck for four years with no
apparent loss in strength of the joint. The (clear) epoxy has yellowed a
bit but the joint seems to be very strong.
Dave