Quick building question

[Gray E Fowler]

Dear Dude-oh so true......



Gray Fowler
Principal Chemical Engineer
Composites Engineering




patterndude at attbi.com
Sent by: discussion-request at nsrca.org
05/07/2003 04:40 PM
Please respond to discussion

 
        To:     discussion at nsrca.org
        cc: 
        Subject:        Re: Quick building question


Hey epoxy cutters,
This may be obvious, but I've seen some statements that can be misleading. 

When anything is added to epoxy, it either evaporates out or stays in the 
mix.  When you add alcohol or acetone to epoxy the mixture will be 
thinner, 
but these solvents will severely weaken the epoxy.  When we paint it on 
balsa 
(as in glassing wings) the solvent evaporates off, but if you use thinned 
epoxy on other applications (where the epoxy is inside a joint) the 
solvent 
molecules will be bound into the epoxy matrix and the result will be 
weaker 
epoxy.

You can prove this by leaving the epoxy/alcohol mix 1/4 inch deep in your 
epoxy mixing cup.  When you come back the next day, it will be cured,but 
rubbery.

The best way to get thin epoxy is to start with a thin epoxy.  Don't start 

with thick epoxy, unless you don't care about strength.

--Lance
> Use denatured alcohol (ethanol) to cut epoxy and be real careful how 
much 
> you use.  Usually a few drops will thin it down a lot, and adding it 
will
> take the cure time from whatever it might have been to overnight or 
longer.
> You can buy it at Walmart in 1 quart cans.
> 
> Adding acetone may thin epoxy, but it will attack foam.  The only thing 
I
> use it to thin is Aerogloss Dope.
> 
> ----------
> From: Bill Mears <bill at mears.com>
> To: discussion at nsrca.org
> Subject: Re: Quick building question
> Date: Wed, May 7, 2003, 9:54 AM
> 
> 
> Can  acetone ne used to cut epoxy ?
> 
> Terry Brox wrote:
> The view was certainly proof of that  LOL
> ----- Original Message -----
> From: "wgalligan" <wgalligan at cnbcom.net> <mailto:wgalligan at cnbcom.net>
> To: <discussion at nsrca.org> <mailto:discussion at nsrca.org>
> Sent: Wednesday, May 07, 2003 9:12 AM
> Subject: Re: Quick building question
> 
> 
> 
> I think he os leaning more towards the "something" thing.
> WG
> 
>  > Are you an epoxy expert or something?  LOL
> 

> BTW, Your new contest mate sure has a cute, um, shoe. LOL
>   ----- Original Message -----
>   From: Gray E Fowler
>   To: discussion at nsrca.org <mailto:discussion at nsrca.org>
>   Sent: Wednesday, May 07, 2003 8:41 AM
>   Subject: Re: Quick building question
> 
> 
> 
>   Steve- Rubbing alcohol is a mixture of isopropyl and and water. Water
> 
> bad. Epoxy hate water.......Plus amines (the epoxy hardener) really do >
> 
> not dissolve well in isopropyl. You are better off with methanol or >
> denatured alcohol which is ethanol with a nasty taste killer so you > 
won't
> drink untaxed alcohol.I do not know what epoxy you are using, but > that
> center reinforcement is easy without cutting the viscosity. Bring > it 
to my
> house I have lots of low viscosity resins.
> 
> 
> 
>   Gray Fowler
>   Principal Chemical Engineer
>   Composites Engineering
> 
> 
>        "Steve Barlow" <stevebarlow at attbi.com> <mailto:stevebarlow at attbi.com>
>         Sent by: discussion-request at nsrca.org
> <mailto:discussion-request at nsrca.org>

>         05/06/2003 10:10 PM
>         Please respond to discussion
> 
> 
>                 To:        <discussion at nsrca.org>
> <mailto:discussion at nsrca.org>
>                 cc:
>                 Subject:        Quick building question
> 
> 
> 
>   Guys,
> 
>   I'm doing the fiberglass reinforcement over the balsa sheeting where >
> 
> the main wings are joined on a .60 size kit.  Can I use rubbing alcohol 
> to
> cut the epoxy with to thin it just a bit?  Do you think that would > 
cause
> me any problems?  It sure would make it easier.
> 
>   Thanks,
>   Steve
> 
> 
> 
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