About 3 months ago, I bought 1 quart of clear gelcoat. Didn't get
around to using it for about a month. When I went to open it up, it
was pretty hard and unuseable.

I bought another quart from the same seller about 2 weeks ago, and
opened it up within a week. This time, the consistency was about that
of grape jelly. At no time was any of this liquid.

I've worked with surfboard fiberglass resin and thought gelcoat would
be similar liquid consistency.

Am I wrong or:

a) Was unlucky, got two bad batches and need to take it up with the
seller?

b) Waited too long to use it? I don't see how it can harden up like
that within a week.

c) Need to add something else to liquify it or thin it, like acetone.
I tried acetone, but it doesn't take out clumping.

d) Leave gel-coat repair to a professional. I've done plenty of
fiberglass repair and didn't think gelcoat would be that different.

A little advice is much appreciated.

L.

Hi, your first batch was too old. The shelf life for polyester resins is
maybe 6 months although it may harden to the point of uselessness before
that. And your retailer may have given you pretty old stuff. But it sounds
like the second batch was fine. There are two types of gel coat; brushing
gel coat and spray gel coat. What you bought is probably brush gel coat.
Spray gel coat is much thinner. Its essentially the same formulation but
they use silica and other additives to thicken it. Usually, I just buy the
one I need. Adding acetone will not work; it flashes off (evaporates) too
soon. You can try adding neat resin but it may not be worth while; just buy
the right stuff and use it with confidence.
Gel coat repairs are not that hard and one can usually achieve a 100% repair
ie invisible! But you do need to match the color first. The concept is the
same as Bondo repairs.

Arnold

You might be able to recover the 2nd batch
by adding some styrene. It's probably too late,
but I've done it.

Bill


"LouiSurfer" wrote in message
ups.com...
About 3 months ago, I bought 1 quart of clear gelcoat. Didn't get
around to using it for about a month. When I went to open it up, it
was pretty hard and unuseable.

I bought another quart from the same seller about 2 weeks ago, and
opened it up within a week. This time, the consistency was about that
of grape jelly. At no time was any of this liquid.

I've worked with surfboard fiberglass resin and thought gelcoat would
be similar liquid consistency.

Am I wrong or:

a) Was unlucky, got two bad batches and need to take it up with the
seller?

b) Waited too long to use it? I don't see how it can harden up like
that within a week.

c) Need to add something else to liquify it or thin it, like acetone.
I tried acetone, but it doesn't take out clumping.

d) Leave gel-coat repair to a professional. I've done plenty of
fiberglass repair and didn't think gelcoat would be that different.

A little advice is much appreciated.

L.

Another gelcoat / flowcoat question...

How thick can gel coat / flowcoat be applied before it becomes a problem?
I have a bubble at the deck/hull join area where evidently a bubble existed
under the gelcoat.
If I fill it with gelcoat it will be approx 2-3 mm thick. Will this
thickness cause a problem?

Can you get good looking results using a brush? Is there a problem with
streaking
lines? My buddy did his boat and possibly screwed up the brush work because it
is very obvious it was brushed on. I think brushing would be a lot easier for
the
boat owner to do themselves, as opposed to spraying.

Sherwin D.

Ystay wrote:

Hi, your first batch was too old. The shelf life for polyester resins is
maybe 6 months although it may harden to the point of uselessness before
that. And your retailer may have given you pretty old stuff. But it sounds
like the second batch was fine. There are two types of gel coat; brushing
gel coat and spray gel coat. What you bought is probably brush gel coat.
Spray gel coat is much thinner. Its essentially the same formulation but
they use silica and other additives to thicken it. Usually, I just buy the
one I need. Adding acetone will not work; it flashes off (evaporates) too
soon. You can try adding neat resin but it may not be worth while; just buy
the right stuff and use it with confidence.
Gel coat repairs are not that hard and one can usually achieve a 100% repair
ie invisible! But you do need to match the color first. The concept is the
same as Bondo repairs.

Arnold

Hi Sherwin,
Generally, you can't escape brush marks when flowcoating. FYI, flowcoating
is where you apply gel coat (usually with a brush) hoping that it will
"flow" out like paint. Gel coat does not do this because it is too thick.
Spray grade gel coat is better for flowcoating with a brush but still does
not leave a pleasing surface. However, if the area is small like say a toe
rail or hull to deck joint then you may have luck using the softest brush
you can find. Most kayaks have their hull-to-deck joints flow coated.
Otherwise, its sanding time! Spraying is not much better; you get orange
peel (looks like the skin of an orange as opposed to the skin of an apple)
also because gel coat is too thick to go on smooth.

Arnold


"sherwindu" wrote in message
...
Can you get good looking results using a brush? Is there a problem with
streaking
lines? My buddy did his boat and possibly screwed up the brush work
because it
is very obvious it was brushed on. I think brushing would be a lot easier
for
the
boat owner to do themselves, as opposed to spraying.

Sherwin D.

Hi Hobbs,
a thick layer of gel coat is not really a good thing because it has no
fiberglass reinforcement. This can cause it to crack at a very slight
knock. The guru's will tell you that the ideal thickness for gel coat is
about 1 to1.5 mm. But in reality, you will find that many GRP parts have
gel coat in excess of that, sometimes up to 4 mm in certain areas. This is
one of the draw backs of brush applied gel coat. But anyway, your repair
should hold fine. Just make sure you catalize the gel coat to cure real
slow otherwise it'll shrink too much and wouldn't bond properly.

Arnold


"Hobbs" wrote in message
...
Another gelcoat / flowcoat question...

How thick can gel coat / flowcoat be applied before it becomes a problem?
I have a bubble at the deck/hull join area where evidently a bubble
existed under the gelcoat.
If I fill it with gelcoat it will be approx 2-3 mm thick. Will this
thickness cause a problem?

Thanks Arnold - I'll give it a go.

One other thing - it's winter here in Australia and the daytime temp is
between 9-15 deg C.
Will the gelcoat properly cure at this low temperature?

"Ystay" wrote in message
...
Hi Hobbs,
a thick layer of gel coat is not really a good thing because it has no
fiberglass reinforcement. This can cause it to crack at a very slight
knock. The guru's will tell you that the ideal thickness for gel coat is
about 1 to1.5 mm. But in reality, you will find that many GRP parts have
gel coat in excess of that, sometimes up to 4 mm in certain areas. This
is one of the draw backs of brush applied gel coat. But anyway, your
repair should hold fine. Just make sure you catalize the gel coat to cure
real slow otherwise it'll shrink too much and wouldn't bond properly.

Arnold


"Hobbs" wrote in message
...
Another gelcoat / flowcoat question...

How thick can gel coat / flowcoat be applied before it becomes a problem?
I have a bubble at the deck/hull join area where evidently a bubble
existed under the gelcoat.
If I fill it with gelcoat it will be approx 2-3 mm thick. Will this
thickness cause a problem?

"Hobbs" wrote in message
...
Thanks Arnold - I'll give it a go.

One other thing - it's winter here in Australia and the daytime temp is
between 9-15 deg C.
Will the gelcoat properly cure at this low temperature?

Hi Hobbs,
no experience in that kind of temperature. But the cure depends a fair bit
on ambient temperature so you may want to catalyse the resin a little more.

Arnold

Hi Arnold,

How would you compare the looks of a painted boat to one sprayed with gel coat?

Sherwin

Ystay wrote:

Hi Sherwin,
Generally, you can't escape brush marks when flowcoating. FYI, flowcoating
is where you apply gel coat (usually with a brush) hoping that it will
"flow" out like paint. Gel coat does not do this because it is too thick.
Spray grade gel coat is better for flowcoating with a brush but still does
not leave a pleasing surface. However, if the area is small like say a toe
rail or hull to deck joint then you may have luck using the softest brush
you can find. Most kayaks have their hull-to-deck joints flow coated.
Otherwise, its sanding time! Spraying is not much better; you get orange
peel (looks like the skin of an orange as opposed to the skin of an apple)
also because gel coat is too thick to go on smooth.

Arnold

"sherwindu" wrote in message
...
Can you get good looking results using a brush? Is there a problem with
streaking
lines? My buddy did his boat and possibly screwed up the brush work
because it
is very obvious it was brushed on. I think brushing would be a lot easier
for
the
boat owner to do themselves, as opposed to spraying.

Sherwin D.