I see that vendors of epoxy sell resin:hardener combinations of 1:2,
1:3, 1:4, etc....

What's going on here ?

Thank you,

Courtney

They are different formulations. Follow mfgr. ratio data exactly. This is
not a place for experiments!
Dave

Dave W wrote:
They are different formulations. Follow mfgr. ratio data exactly. This is
not a place for experiments!
Dave


Thank you.

I can see I failed to adequately state my concern :-)

Chemically, what is the difference in the resins when using the
different formulations that require different amounts of hardener ?

If only the viscosities are different, how are these different
formulations attained ?

Also, what is the difference in the hardeners, if any ?

Is there a known website that fully delves into this without bias ?

Thank you,
Courtney

Go to http://www.systemthree.com/index_2.asp -- register -- download "The
Epoxy Book" in pdf -- read the introduction and Basic Chemistry. Unless
you're an organic chemist, this is all you'll be able to digest. (I can
almost understand it while I'm reading it, but it's been fifty years since I
took P-Chem.)

Note that only a very foolish company would give you the exact details of
their formulations. They've spent many year$$$ coming up with these. I
believe they all start with the same basic resins from DuPont or whoever.
The magic is in the additives and there are huge differences between brands.
Contrast the glasslike stuff from the hardware store for mending china with
the resilient bond formed for building boats.

As far as ratios go, the 5:1 used by the Gougeon brothers is harder for the
user to measure accurately than the 2:1 used by System Three, but it
apparently is closer to the basic resin as brought in by tank car.

The appendices of "The Epoxy Book" give mechanical properties and usage;
e.g. coverage, curing times, etc.

Roger

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

"Courtney Thomas" wrote in message
nk.net...
Dave W wrote:
They are different formulations. Follow mfgr. ratio data exactly. This
is not a place for experiments!
Dave
Thank you.

I can see I failed to adequately state my concern :-)

Chemically, what is the difference in the resins when using the different
formulations that require different amounts of hardener ?

If only the viscosities are different, how are these different
formulations attained ?

Also, what is the difference in the hardeners, if any ?

Is there a known website that fully delves into this without bias ?

Thank you,
Courtney

Roger Derby wrote:
Go to http://www.systemthree.com/index_2.asp -- register --
download "The Epoxy Book" in pdf

Good resource, thanks!

--
dadiOH
____________________________

dadiOH's dandies v3.06...
....a help file of info about MP3s, recording from
LP/cassette and tips & tricks on this and that.
Get it at http://mysite.verizon.net/xico

Epoxide resin is a commodity. They all buy it in bulk from the same
chemical company. Then they try to make theirs look different to the
consumer and advertise heavily. I doubt any will tell you what actually
makes their brand different chemically.

Generally the 1:1 is considered easier to measure and mix. I use very
small quantities and can measure equal amounts by eye down to one drop of
each to fill a couple of screw holes.

--
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Courtney Thomas wrote:

Dave W wrote:

They are different formulations. Follow mfgr. ratio data exactly.
This is not a place for experiments!
Dave

Thank you.

I can see I failed to adequately state my concern :-)

Chemically, what is the difference in the resins when using the
different formulations that require different amounts of hardener ?

If only the viscosities are different, how are these different
formulations attained ?

Also, what is the difference in the hardeners, if any ?

Is there a known website that fully delves into this without bias ?

Thank you,
Courtney

----------------
Hi Courtney


There are about three different epoxy resins (bis A, F, and novolac).
Just about everyone uses Bis A....
There are about 60 different curing agents that can be used.

So.... most epoxies are, or can be, a blend of different curing agents.
On top of that there are thinks like nonyl ... that can be added to part
A or B to even out the mix ratios, lower the price, change visc. etc.

The curing agents are a lot more expensive than the resins so
forumulating an epoxy with with a 4 to 1 or so mix ratio (instead of a 1
to 1 or 2 to 1 ratio) saves the formulator $$ (or increases their profits)

paul oman - progressive epoxy polymers, Inc.
---------------------------------------------------------------

--


"Living on Earth is expensive, but it does include
a free trip around the Sun every year."


============================================
PAUL OMAN Progressive Epoxy Polymers, Inc.
Frog Pond Hollow - 48 Wildwood Drive
Pittsfield NH 03263
10:30-3:30 Monday-Thur EST 603-435-7199
VISA/MC/Discover/Paypal

http://www.epoxyproducts.com
============================================

Paul Oman wrote:
Courtney Thomas wrote:

Dave W wrote:

They are different formulations. Follow mfgr. ratio data exactly.
This is not a place for experiments!
Dave

Thank you.

I can see I failed to adequately state my concern :-)

Chemically, what is the difference in the resins when using the
different formulations that require different amounts of hardener ?

If only the viscosities are different, how are these different
formulations attained ?

Also, what is the difference in the hardeners, if any ?

Is there a known website that fully delves into this without bias ?

Thank you,
Courtney


----------------
Hi Courtney


There are about three different epoxy resins (bis A, F, and novolac).
Just about everyone uses Bis A....
There are about 60 different curing agents that can be used.

So.... most epoxies are, or can be, a blend of different curing agents.
On top of that there are thinks like nonyl ... that can be added to part
A or B to even out the mix ratios, lower the price, change visc. etc.

The curing agents are a lot more expensive than the resins so
forumulating an epoxy with with a 4 to 1 or so mix ratio (instead of a 1
to 1 or 2 to 1 ratio) saves the formulator $$ (or increases their profits)
paul oman - progressive epoxy polymers, Inc.
---------------------------------------------------------------

Thank you Paul.

What's the difference between bis, A, F and novolac ?

What do the 'curing agents' actually do ? Catalyze the polymerization ?

Is the reason that everyone doesn't use the same 'hardener', because
different ones lend a different character to the curing process,
otherwise, the same end product... results ?

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 ?

Any online references that address this ?

Appreciatively,

Courtney

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