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From: Evan Dallas <evand_at_pensionresourcegroup.com>
subject: [Paddlewise] Epoxy questions
Date: Tue, 14 Jun 2005 17:45:43 -0700
I have some Titan brand marine epoxy with the fast hardener.  Even in a 
60 degree room, I find that if I mix much more than about 3/4 ounce, 
after a few minutes, the stuff goes into exothermic mode, producing a 
chain reaction where it starts to bubble and almost immediately harden.  
I realize I can use a larger container to help dissipate the heat, but 
it ends up wasting a fair amount by being so spread out.  I've heard 
that if you ice your mixing container, the reaction can be avoided at 
the expense of dealing with a thicker mix.  Are there any other 
disadvantages to doing this?  My thought was to ice it until it's 
applied, then move the project (I'm making fiberglass covered J-cradles 
for my roof rack) to a warmer room to cure.

And as long as we're on the subject, the best deal I've found for 
no-blush marine epoxy is through http://www.epoxyproducts.com (seems 
like a reputable dealer, but in serious need of a skilled web designer), 
where in small quantities, you can get 28 ounces for US$12.50 or 6 
quarts for $69.  Anyone know of a better source?  I tried buying it 
locally, but have had a surprisingly hard time locating it (other than 
the quite expensive West Systems brand from a marine store).

Thanks for any info.

Evan Dallas
Woodinville, Washington
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From: Michael Daly <mikedaly_at_magma.ca>
subject: Re: [Paddlewise] Epoxy questions
Date: Tue, 14 Jun 2005 21:23:00 -0400
On 14 Jun 2005 at 17:45, Evan Dallas wrote:

> I've heard that if you ice your mixing container, the reaction can be
> avoided at the expense of dealing with a thicker mix.

Wouldn't it be easier to switch to a slow-cure hardener?

Mike
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From: Dave Kruger <kdruger_at_pacifier.com>
subject: Re: [Paddlewise] Epoxy questions
Date: Tue, 14 Jun 2005 20:11:17 -0700
 "Evan Dallas" <evand_at_pensionresourcegroup.com> wrote:


>I have some Titan brand marine epoxy with the fast hardener.  Even in a 60 
>degree room, I find that if I mix much more than about 3/4 ounce, after a 
>few minutes, the stuff goes into exothermic mode, producing a chain reaction 
>where it starts to bubble and almost immediately harden.

Evan, three suggestions:

1. Mix in a larger container with a broader bottom, using just one side of 
the container (a square bottomed one is good for this -- use a corner), then 
as soon as it is mixed, spread it out over the entire bottom of the 
container.  The greater the surface area, the longer the pot life.

2. Borrow an old triple beam balance and weigh out your ingredients, to make 
smaller batches, just the amount you can use before the exotherm.  Measuring 
volumetrically, it is hard to get precise ratios in small batches.  Is this a 
2:1 epoxy?  If so, then the weight ratios are probably close to 100:44 :: 
resin:hardener

3. As soon as it is mixed, slap it onto the work surface and spread it out. 
This means you need to be ready before mixing.

--
Dave Kruger
Astoria, OR
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From: Erik Sprenne <sprenne_at_netnitco.net>
subject: Re: [Paddlewise] Epoxy questions
Date: Wed, 15 Jun 2005 00:53:51 -0500
> I have some Titan brand marine epoxy with the fast hardener.

> I've heard
> that if you ice your mixing container, the reaction can be avoided at
> the expense of dealing with a thicker mix.  Are there any other
> disadvantages to doing this?

I agree with Mike that buying a slower hardener is probably the best
choice.

The risk you run with trying to cool already-mixed epoxy is that once you
mix the two parts, the chemical reaction starts, and any attempt to cool
(which takes time) may be neutralized by the exotherm of the curing epoxy
(which doesn't wait).  If the epoxy starts 'going off' half way through
your job, then your project may be trashed or require significant
'fix-it' efforts.

Even if you are successful in quickly cooling the epoxy, it may not
easily/completely wet out glass cloth, may not penetrate into the wood
surface to give you the strongest possible bond, and may not release any
air bubbles that are inadvertently worked into the epoxy - or may
generate 'pinholes' when it does.  And if you try cooling the resin and
hardener prior to mixing, it may be hard to get a uniform and thorough
mix of the two parts, which may result in a different set of problems.

Unless you're working with epoxy full-time, paying a little more for one
of the name brand products, and maybe even buying both fast and slow
hardeners often used in boat-building is, IMO, a good investment.  See
http://www.westsystem.com/
http://www.masepoxies.com/
http://www.systemthree.com/
http://www.raka.com/

And be sure to work safely with epoxy.  Minimize inhalation of epoxy
fumes and avoid all skin contact, as epoxy is a sensitizer and can affect
those individuals sensitive to epoxy - and you won't know if you're
sensitive or not until it's too late......  The MAS and West System web
sites have good safety write-ups that anyone working with epoxy should
read - and pay attention to.  See
http://www.masepoxies.com/safety.htm
http://www.westsystem.com/ (link to safety info under green 'Go To' bar
on left)

Erik Sprenne
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From: Dave Kruger <kdruger_at_pacifier.com>
subject: Re: [Paddlewise] Epoxy questions
Date: Wed, 15 Jun 2005 01:07:49 -0700
"Evan Dallas" <evand_at_pensionresourcegroup.com> wrote:

> I have some Titan brand marine epoxy with the fast hardener.

> I've heard
> that if you ice your mixing container, the reaction can be avoided at
> the expense of dealing with a thicker mix.  Are there any other
> disadvantages to doing this?

As others have already said:  slower hardener is definitely the best fix.

Couple disadvantages of icing the mixing container:

1. Will cause moisture to condense in the mix.

2. Much more difficult to get good mixing, because the resin and hardener 
will thicken.

3. Colder, thicker mix will not wet out glass, and will not penetrate wood as 
well.

--
Dave Kruger
Astoria, OR 
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