OPINION!

One size does not fit all. One design is not satisfying to all people.

I've gotten used to System Three which uses a 2:1 mix. West System (Gougeon
Brothers) uses a 5:1 mix. Both are vendors who have satisfied customers for
decades. Neither is bamboozling the customers. They use their own products
and document the results. IMHO, the lower the ratio, the less you
compromise the final product, but "acceptable" is a compromise and there is
a range of "good enough."

The stuff we used on the F-16, F-22, and A-12 was quite different from what
I use in the barn for my boat, and the difference didn't happen in the
user's shop. Are you prepared to use an oven and follow a careful post-cure
time/temperature schedule to achieve the results you want? Caution, it may
take several tries to get it right. On A-12, several LARGE center wing
assemblies were unusable because the thermostat wasn't accurate.

The stuff from Dow is not suitable for use in boat building. We typically
use a "room temperature" cure and want a bond which is compatible with a
wooden structure. Check out http://epoxy.dow.com/products/p-liquid.htm
Building an aircraft structure, repairing a china cup, patching an engine
block ... all require different additives.

Boat builders are not a stupid, uneducated group. Don't think you are the
first to wonder about "contributed value."

Roger (BSE-Physics, Univ. of Illinois)

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

"Courtney Thomas" wrote in message
ink.net...
Paul Oman wrote:
snip
So, is the bottom line that....if you can find a 1:1 or 2:1 mix that will
satisfy your needs, that's the best way to go and the more exotic
formulations are also more circumscribed in terms of usage hence more
likely to be inappropriately applied, such as low temp applications, etc.,
that ultimately don't properly cure due to a flawed application process,
hence fail ?

Would this be just one more example of vendors bamboozling customers with
attempts at masking a generic product with proprietary 'technology',
witness the auto manufacturers and their glomming onto electronics, or do
some actually have worthwhile differences and related costs and
PERFORMANCE, that justify their claims and charges ?

Roger Derby wrote:

The stuff from Dow is not suitable for use in boat building.

Not quite.

There are only 3-4 basic resin suppliers in the world.

Dow, Ciba-Geigy and Shell come to mind.

There may be another one or two.

Each of the major formulators works with typically only one resin supplier.

That's enough.

I know my suppliers are a Dow house.

They supply material to build more than one boat builder including me.

Lew

With the resources available in your VERY large home city and your skills at
purchasing, I'm not surprised. If I'm not mistaken, you're buying the resin
in 55 gallon drums.

Where do you get your hardeners and who supplied the formulae?

Roger

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

"Lew Hodgett" wrote in message
k.net...
Roger Derby wrote:
The stuff from Dow is not suitable for use in boat building.

Not quite.
There are only 3-4 basic resin suppliers in the world.
Dow, Ciba-Geigy and Shell come to mind.
There may be another one or two.
Each of the major formulators works with typically only one resin
supplier.
That's enough.
I know my suppliers are a Dow house.
They supply material to build more than one boat builder including me.

Lew

Roger Derby wrote:


Where do you get your hardeners and who supplied the formulae?


I use Diversified Materials Corp in San Diego.

The formulator supplies the chemistry.

Lew

On Thu, 10 Nov 2005 04:27:41 +0000, Lew Hodgett wrote:

Roger Derby wrote:

The stuff from Dow is not suitable for use in boat building.

Not quite.

There are only 3-4 basic resin suppliers in the world.

Dow, Ciba-Geigy and Shell come to mind.

[snip]

I think Shell sold their epoxy works to Resolution Performance Products.
There is a lot of information about various formulations at
www.resins.com, the Resolution website.

--Mac

Hey, nobody says you can't reinvent the wheel. What irritates me is that
the people who have spent years developing the proper formulations and
techniques are expected to work for free. Sort of like saying "Hey.
There's nothing in this book except the letters I learned in kindergarten.
Why should I pay the author?" If enough people adopt that attitude, no one
will bother publishing anything.

Maybe the rest of you find boatbuilding so easy that you can devote your
energies to doing the tasks that come bundled with a purchase from System
Three or West Systems; product support, trouble shooting, documentation,
storage, shipping and handling. I'd rather buy small quantities of
ready-to-use stuff in order to spread the cost over time and profit from
their mistakes.

A recurring theme in the criticism of technical reports is that they never
discuss the blind alleys, fires, explosions and other events that ran the
project cost up to two or three times what was expected. To read the report
or listen to the presentation one would think that it was just a matter of
doing X, then Y, and then Z; of course.

At GD it was common to see a gallon can of epoxy blazing away on the
apron -- thermal runaway. Another recurring problem was quality control --
how do you know that the "wet out" was complete when the exterior looks
fine. Ultrasound scanning of every square inch is messy and expensive. (To
couple the transducer to the skin being examined, one uses a gel.) It also
requires operator skills that take time to develop. ...

Ah, well. Sorry. Rant over.
Roger

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

"Mac" wrote in message
news
On Thu, 10 Nov 2005 04:27:41 +0000, Lew Hodgett wrote:

Roger Derby wrote:

The stuff from Dow is not suitable for use in boat building.

Not quite.

There are only 3-4 basic resin suppliers in the world.

Dow, Ciba-Geigy and Shell come to mind.

[snip]

I think Shell sold their epoxy works to Resolution Performance Products.
There is a lot of information about various formulations at
www.resins.com, the Resolution website.

--Mac