I want to know the proper way to apply epoxy on scored core material.
Scored core material has many cuts on both sides to allow it to be
bent slightly. I am under the impression that I need to apply epoxy
inside the cuts. The method that I have come across in web site is to
lay the scored core material on a piece of 10" PVC pipe to expose the
cuts; then we can apply epoxy into the cuts. This sounds good. I cut
a 5-gal bucket in half (that is around 10" diameter), and layed the
scored core material (Corecell) on top of it. But I found that the
cuts were not opened that much, and I had a problem getting epoxy into
the cuts. I could only manage to get the epoxy only half way into the
cuts. I ended up opening the cuts by hand; but this would easily
cause the core material to get separated along the cuts, and this was
not convenient.

My questions a

o Is 10" diameter pipe too wide? Which size do you
recommend?

o Do I need to use very thin penetrating epxoy instead of
thickening it? I thought I am supposed to thicken it
first before adding it to the cuts.

o Is applying epoxy to 1/2 depth of a cut good enough?
Do I need to apply epoxy to the full depth of the cut?

Thanks in advance for any help.

Jay Chan

I do not know what you try to do, but base on my experience the gaps
supposed to hallow/empty. What is my experience ? I built 38ft
sailboat Spray.
I use corecell as a sandwich construction. The idea was to keep
sandwich as light as possible. After corecell was installed I used
very light putty – to fill gaps only on the top.
Next was sanding and on the top fibreglass with resin.
In short – do not fill the gaps with resin.
I hope it helps.
Mada

On Jun 13, 8:19*pm, wrote:
I do not know what you try to do, but base on my experience the gaps
supposed to hallow/empty. What is my experience ? I built 38ft
sailboat Spray.
I use corecell as a sandwich construction. The idea was to keep
sandwich as light as possible. After corecell was installed I used
very light putty – to fill gaps only on the top.
Next was sanding and on the top fibreglass with resin.
In short – do not fill the gaps with resin.
I hope it helps.
Mada

I was referring to an article:
http://www.boatbuilding.net/article..../01/24/1330205

It said to put scored balse core material on top of a 10" PVC tube to
open the cuts and then apply epoxy mixture into the cuts.

Now, I re-read the article, and I find that he used 3/4" core, and I
am using 3/8" core. This means his is double the thickness of mine.
I think this explains why his core can open up using a 10" PVC tube,
and mine cannot. I probably needs to put the 3/8" core in a smaller
diameter pipe than 10" if I want to apply epoxy inside the cuts (may
be 6" pipe).

Having said this, seem like you don't need to apply epoxy into the
cuts and your boat is doing just fine. I guess applying epoxy into
the cuts may be a "belt and suspender" kind of thing. Thanks for
pointing out a different approach.

Jay Chan

Jay Chan wrote:
On Jun 13, 8:19 pm, wrote:

I do not know what you try to do, but base on my experience the gaps
supposed to hallow/empty. What is my experience ? I built 38ft
sailboat Spray.
I use corecell as a sandwich construction. The idea was to keep
sandwich as light as possible. After corecell was installed I used
very light putty – to fill gaps only on the top.
Next was sanding and on the top fibreglass with resin.
In short – do not fill the gaps with resin.
I hope it helps.
Mada


I was referring to an article:
http://www.boatbuilding.net/article..../01/24/1330205

It said to put scored balse core material on top of a 10" PVC tube to
open the cuts and then apply epoxy mixture into the cuts.

Now, I re-read the article, and I find that he used 3/4" core, and I
am using 3/8" core. This means his is double the thickness of mine.
I think this explains why his core can open up using a 10" PVC tube,
and mine cannot. I probably needs to put the 3/8" core in a smaller
diameter pipe than 10" if I want to apply epoxy inside the cuts (may
be 6" pipe).

Having said this, seem like you don't need to apply epoxy into the
cuts and your boat is doing just fine. I guess applying epoxy into
the cuts may be a "belt and suspender" kind of thing. Thanks for
pointing out a different approach.

Jay Chan


Epoxy resin - by itself - is hardly ever used thie way.
It's too heavy and too brittle.

It is almost always used with a filler added.
Microballons were suggested. For foam fillets, that's probably fine.
For more structural needs, cotton is often used.

It sounds to me like you need to do some homework first.
Get the to thy library, or Amazon and learn the basics.

For what it's worth,

Richard

On Jun 13, 8:19*pm, wrote:
I do not know what you try to do, but base on my experience the gaps
supposed to hallow/empty. What is my experience ? I built 38ft
sailboat Spray.
I use corecell as a sandwich construction. The idea was to keep
sandwich as light as possible. After corecell was installed I used
very light putty – to fill gaps only on the top.
Next was sanding and on the top fibreglass with resin.
In short – do not fill the gaps with resin.
I hope it helps.
Mada

I read that article one more time, and I think you are right to say
that
we don't need to apply epoxy mixture into the cuts of a scored
Corecell
core material. The author of that article said that he needed to
apply
epoxy mixture into the cuts because he was using balsa core (that can
rot); by filling the cuts in a balsa core, he can prevent water from
easily
spreading from one area of the balsa core to the next area just in
case
water finds its way into the core. Seem like this is not an issue
with
core made from man-made material such as Corecell. Good, this means
I can skip this step.

Thanks for the suggestion.

Jay Chan

On Jun 14, 8:20*am, cavelamb himself wrote:
Jay Chan wrote:
On Jun 13, 8:19 pm, wrote:

I do not know what you try to do, but base on my experience the gaps
supposed to hallow/empty. What is my experience ? I built 38ft
sailboat Spray.
I use corecell as a sandwich construction. The idea was to keep
sandwich as light as possible. After corecell was installed I used
very light putty – to fill gaps only on the top.
Next was sanding and on the top fibreglass with resin.
In short – do not fill the gaps with resin.
I hope it helps.
Mada

I was referring to an article:
http://www.boatbuilding.net/article..../01/24/1330205

It said to put scored balse core material on top of a 10" PVC tube to
open the cuts and then apply epoxy mixture into the cuts.

Now, I re-read the article, and I find that he used 3/4" core, and I
am using 3/8" core. *This means his is double the thickness of mine.
I think this explains why his core can open up using a 10" PVC tube,
and mine cannot. *I probably needs to put the 3/8" core in a smaller
diameter pipe than 10" if I want to apply epoxy inside the cuts (may
be 6" pipe).

Having said this, seem like you don't need to apply epoxy into the
cuts and your boat is doing just fine. *I guess applying epoxy into
the cuts may be a "belt and suspender" kind of thing. *Thanks for
pointing out a different approach.

Jay Chan

Epoxy resin - by itself - is hardly ever used thie way.
It's too heavy and too brittle.

It is almost always used with a filler added.
Microballons were suggested. For foam fillets, that's probably fine.
For more structural needs, cotton is often used.

It sounds to me like you need to do some homework first.
Get the to thy library, or Amazon and learn the basics.

For what it's worth,

Richard- Hide quoted text -

- Show quoted text -

No, I am not talking about using epoxy to fill in
big gaps or fairing. I am talking about filling in the
grid pattern cuts in scored core material. Some
core materials are scored in order for people to
easily bend it to match the curve shape of the
surface. I was not sure if I need to fill in the
cuts. Seem like I don't need to fill in the cuts
as long as I am using man-made material as
core instead of using balsa core.

Jay Chan

Hi when applying epoxy to penetrate an material I always thin it with
Acetone which carries the epoxy into the material. The second coat use
normal mix epoxy, works for me.

Sal

"Jay Chan" wrote in message
...
I want to know the proper way to apply epoxy on scored core material.
Scored core material has many cuts on both sides to allow it to be
bent slightly. I am under the impression that I need to apply epoxy
inside the cuts. The method that I have come across in web site is to
lay the scored core material on a piece of 10" PVC pipe to expose the
cuts; then we can apply epoxy into the cuts. This sounds good. I cut
a 5-gal bucket in half (that is around 10" diameter), and layed the
scored core material (Corecell) on top of it. But I found that the
cuts were not opened that much, and I had a problem getting epoxy into
the cuts. I could only manage to get the epoxy only half way into the
cuts. I ended up opening the cuts by hand; but this would easily
cause the core material to get separated along the cuts, and this was
not convenient.

My questions a

o Is 10" diameter pipe too wide? Which size do you
recommend?

o Do I need to use very thin penetrating epxoy instead of
thickening it? I thought I am supposed to thicken it
first before adding it to the cuts.

o Is applying epoxy to 1/2 depth of a cut good enough?
Do I need to apply epoxy to the full depth of the cut?

Thanks in advance for any help.

Jay Chan