Can anyone suggest a good source of technical info on plug making for boat
hulls and liners?
Thanks in advance,
M.J.Johnson

A company in Sarasota? Florida called "Fiberglass Coatings" has a pretty
good free (I think) manual on this subject. They also sell materials
pretty inexpensively. I've ordered from them twice and had good luck.
Here is the address of their website. http://www.fgci.com
Go to the "how to" section. I think the hardcopy catalogue/manual goes
into more depth than the web site.
This source may be too simplified for you but I think they also sell
books on the subject.
Good luck
SteveJ

R. Smith/M.J. Johnson wrote:
Can anyone suggest a good source of technical info on plug making for boat
hulls and liners?
Thanks in advance,
M.J.Johnson

I recently began using my first 1 1/2 galolon of Fiberglass Coatings 2:1
slow cure epoxy. It seems a bit on the thick side, but cures beautifully.
Seems like the thicker epoxy doesn't go as far as the thinner WEST stuff
does. Should I compensate by adding a bit when I place my next order, or is
the issue just my perception of the "new" brand?

Thanks,

James

FGCI and Raka resins are both noticably thicker than West 105. It is way
to thick for light weight scrim and a real PITA when you try to wet out
heavier knitted cloth like DB170 or 1808. The thickness actually helps
when you are covering with 5 or 6 oz woven cloth because it takes less
coats to fill the weave. The actual coverage per gallon is about the
same because you can fill 6 oz cloth with two coats rather than 3 with
West but small pools will not flow out on their own so you have to
carefully squeegee evenly or do a lot more sanding.

I use several different resins depending on the job and the required
open time. The FGIC laminating resin is most ecconomical for covering
plywood with woven cloth. Pre-thickened FGCI epoxy adheasive is great
for laminating ply skins to foam cores. West 105 is better for making
up fairing putties and general bonding and ProSet is by far better for
vacuum bagging heavy sections of unidirectional and biaxial knitted
material. It has a higher ultimate strength, lowest viscosity and
longest working time.

James W. Sloan wrote:
I recently began using my first 1 1/2 galolon of Fiberglass Coatings 2:1
slow cure epoxy. It seems a bit on the thick side, but cures beautifully.
Seems like the thicker epoxy doesn't go as far as the thinner WEST stuff
does. Should I compensate by adding a bit when I place my next order, or is
the issue just my perception of the "new" brand?

Thanks,

James



--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

The thickness actually helps
when you are covering with 5 or 6 oz woven cloth because it takes less
coats to fill the weave.

Glenn's giving you good advice on epoxy here. I've had the same exp with FGCI.
It's higher viscosity than many others. I use it fine on 8 oz cloth & below
and layup in a mold is nice too. It's very forgiving of mixing. Be sure to
squeegee. I like to use it in cooler weather 75 to give me a little more time
to do that.
Greg Sefton

This brings up a question I have had for a long time. Maybe the Polymer
Chemist that posts here occasionally (sorry, forgot the name) could
explain.

Why is there such a difference in viscosity between various brands of
epoxy. I don't mean the penetrating stuff, just the regular resins we
use for gluing and laminating. If epoxy is almost 100% solids, what is
different in the formulations that give such a difference or is it a
difference in how the base resins are made that the formulator uses for
their individual products.

Regards, Ron

I think Kern couldn't take Jax and his ilk. He left long ago.

The actual base resin is only made by a couple of companies. West,
Mass, FGIC, Raka, System One and others are "formulators". They get the
base resin and mix it with other chemicals to adjust the viscosity, cure
rate, ultimate strength and resistance to heat to produce what they feel
is the best combination of price and performance that their customers
need.

Everything is a trade off. Lowering the viscosity for easy wettout
while maintaining strength and HDT adds to the cost so those tend to be
the most expensive. At the other end adding thinners, pigments and
fillers to produce epoxy floor paint is the cheapest. The goal is to
balance the cost, workability and performance for a particular market.

The trick is to experiment with several formulations and for a
particular job choose the one that will do best for the least amount of
money.


Ron Thornton wrote:

This brings up a question I have had for a long time. Maybe the Polymer
Chemist that posts here occasionally (sorry, forgot the name) could
explain.

Why is there such a difference in viscosity between various brands of
epoxy. I don't mean the penetrating stuff, just the regular resins we
use for gluing and laminating. If epoxy is almost 100% solids, what is
different in the formulations that give such a difference or is it a
difference in how the base resins are made that the formulator uses for
their individual products.

Regards, Ron


--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

On Wed, 15 Oct 2003 13:48:59 -0400, "R. Smith/M.J. Johnson"
wrote something
.......and in reply I say!:

Your post is 4 days old, and has been addressed with the best of
intent by some of the long-standing and respected posters. Are you for
real?

Can anyone suggest a good source of technical info on plug making for boat
hulls and liners?
Thanks in advance,
M.J.Johnson


************************************************** ****************************************
Whenever you have to prove to yourself that you are
not something, you probably are.

Nick White --- HEAD:Hertz Music
Please remove ns from my header address to reply via email
!!
")
_/ )
( )
_//- \__/

We really have not answered his question. FGIC has some basic info but
I have not found any real detail on the net. What I have learned about
making plugs (patterns in the parlance of other casting industries) came
from metal casting.

Building a plug for a hull is fairly simple. Get a copy of Gougeon on
Boatbuilding and build as described but use cheap materials like door
skins and Bondo. Plugs for decks nd interior frames are a different
matter. A mold must have some draft for the part to release with out
damage and all the different areas must have compatible draft. That
takes a considerable amount of geometric planning.

It also takes a lot more work to build interior plugs. Once you build
it you have to be able to spray it with a mold finish like Duratec, sand
to 220, wet sand to 600, polished, compounded and waxed. I just spent
the last two weeks just building male molds for head surrounds, shower
pans and gray water tanks in a similar way. I can't imagine building a
deck or interior plug on my own.

Old Nick wrote:

On Wed, 15 Oct 2003 13:48:59 -0400, "R. Smith/M.J. Johnson"
wrote something
......and in reply I say!:

Your post is 4 days old, and has been addressed with the best of
intent by some of the long-standing and respected posters. Are you for
real?


Can anyone suggest a good source of technical info on plug making for boat
hulls and liners?
Thanks in advance,
M.J.Johnson



************************************************** ****************************************
Whenever you have to prove to yourself that you are
not something, you probably are.

Nick White --- HEAD:Hertz Music
Please remove ns from my header address to reply via email
!!
")
_/ )
( )
_//- \__/

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com