[NSRCA-discussion] Epoxy Question
Jay Marshall
lightfoot at sc.rr.com
Wed Nov 21 06:15:33 AKST 2007
The answers may be here:
http://www.fiberglassonline.biz/methanol-gallon.html
Jay Marshall
-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of
glmiller3 at suddenlink.net
Sent: Wednesday, November 21, 2007 8:02 AM
To: NSRCA Mailing List; Don Ramsey
Cc: Don Ramsey
Subject: Re: [NSRCA-discussion] Epoxy Question
Guys, I thought the idea was to allow you to spread it thinner so that the
end result was lighter. Let's do a test where we coat a piece of 3 X 6 inch
balsa with thinned and unthinned epoxy and see if the thinned is actually
lighter. I would have done this already but I'm AFW (away from workshop) on
vacation this week.
George
---- Don Ramsey <don.ramsey at suddenlink.net> wrote:
> My test with 5 minute expoxy and 70 % alcohol was a disaster. 1 oz expoxy
and 1 oz alcohol after curing only lost about a gram in the cup. The mixture
was a rubbery substance that crumbled when pressure was applied. No
strength at all. Spreading thin for the cure would have lost more weight
but probably not substantially. So, I no longer believe the alcohol
evaporates and you are only left with expoxy. The molecular structure
changes and not for the better. I'm not going to thin anything that needs
strength.
>
> Don
>
> ----- Original Message -----
> From: Bob Kane
> To: NSRCA Mailing List
> Sent: Tuesday, November 20, 2007 6:32 PM
> Subject: Re: [NSRCA-discussion] Epoxy Question
>
>
> This reminds me of a workshop incident 29 years ago . . . . I was
making a spacer out of 5/8" particle board to put an aftermarket aircleaner
on my 1978 Chevy Monza. I decided to "fuelproof" the spacer, but wanted to
get it done in a hurry, so I mixed up a batch of 5 minute epoxy and thinned
it quite a bit with alcohol. I painted the mixture on the spacer and was
waiting for it to cure, when all of a sudden an epoxy "snake" started
growing out of the mixing cup. It made kind of a hissing, snapping sound,
and grew to be about 8 inches long. I figured the epoxy heated up enough to
"boil" the epoxy while it was still somewhat pliable. The result was an
interesting honey colored rock hard piece of epoxy foam. The epoxy on the
particle board cured fine.
>
> Bob Kane
> getterflash at yahoo.com
>
>
>
> ----- Original Message ----
> From: "patterndude at tx.rr.com" <patterndude at tx.rr.com>
> To: NSRCA Mailing List <nsrca-discussion at lists.nsrca.org>
> Cc: "Atwood, Mark" <atwoodm at paragon-inc.com>
> Sent: Tuesday, November 20, 2007 4:48:13 PM
> Subject: Re: [NSRCA-discussion] Epoxy Question
>
> Mr Fowler is out saving the world through explosives, but as a foot
soldier in the cause, here's my understanding (and experience):
> Alcohol and acetone both mix into the resin/hardener solution. This
makes is harder for crosslinking to occur and it separates the epoxy
molecules trapping the alcohol. THe resulting solid will be a bit rubbery
because of the trapped alcohol. Acetone is a more powerful solvent than
alchohol and is beter for cleaning and thinning, but is also better for
making rubber.
> The answer to the original question is really somewhat obvious.
Alcohol is volatile and will evaporate from the surface of the liquid in
your mixing cup. As the epoxy cures, it exotherms (heats up) and this will
also increase the evaporation. However, not all will evaporate. Whatever
doesn't will be bound into the final rubbery solid. THe amount left behind
is a variable affected by the size of the cup, heat in the room, amount of
epoxy mixed, speed of cure, etc.
> The one time alcohol is OK to leave in the mix is when glassing. The
very thin layer allows virtually all the alcohol to evaporate.
>
> Also, Mike says he is using 91% alcohol. That means 9% water. Water is
never good. He should go to home depot and buy a gallon of Denatured
Alcohol. This is pretty close to 100% pure and it is less than half the
price.
>
> --Lance
>
> ---- "Atwood wrote:
>
> =============
> Actually...my thought goes the other direction. That if indeed the
> alcohol actually MIXES with the epoxy, then it would truly bind and in
> some way harden as part of the overall mixture. Epoxy "cures"...rather
> than flashing, so my guess...and it's truly a guess...is that it would
> be much closer to the original total weight of 2 oz.
>
>
>
> Still waiting patiently for our resident epoxy deity, previously
> referred to as Master Fowler to take away the mystery and lead us oh so
> graciously to the light...
>
>
>
> From: nsrca-discussion-bounces at lists.nsrca.org
> [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of wgalligan
> Sent: Tuesday, November 20, 2007 9:52 AM
> To: Don Ramsey; NSRCA Mailing List
> Subject: Re: [NSRCA-discussion] Epoxy Question
>
>
>
> OK, I'll take a stab. After the alcohol evaporates you would have the
> same mass or weight of epoxy that you started with. AND to reiterate
> what I learned from the Master Fowler, thinning epoxy, if I remember
> right, changes the molecular structure weakening the mixture. It will
> also cause the epoxy to shrink over time. BTDT.
>
>
>
> Wayne Galligan
>
>
>
> waiting for Master to speak
>
> ----- Original Message -----
>
> From: Don Ramsey <mailto:don.ramsey at suddenlink.net>
>
> To: NSRCA Mailing List <mailto:nsrca-discussion at lists.nsrca.org>
>
>
> Sent: Tuesday, November 20, 2007 8:53 AM
>
> Subject: [NSRCA-discussion] Epoxy Question
>
>
>
> Breaking news. Here's something from Mike Harrison that will be
> of interest to the list.
>
> Don
>
>
>
>
>
> Ok, think about this, take 1 oz epoxy and thin with 1 oz alcohol
> (91%).? After curing how much do you think it weighs and tell me why.
>
>
>
> Mike
>
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