[Rhodes22-list] CB trunk Surgery - Roger's Recommended MOC

[Roger Pihlaja]

Bob,

No, MEK does not interfere with the epoxy curing reactions.  What will
happen after the solvent evaporates away & the epoxy is cured, is that you
will end up with thiner coating of epoxy on the substrate than would be
possible if you used straight unthickened epoxy.  Note, that at epoxy
concentrations < about 15%wt (i.e. > 85%wt solvent), there will not be
sufficient epoxy left after the solvent evaporates to build a continuous
coating.  In that case, you will tend to get separate droplets or blobs of
epoxy.  These droplets will tend to form at fiber crossing points or places
with very narrow passages in a porous substrate due to the suface tension in
the liquid epoxy.

Mix the MEK with the resin & get the resin completely dissolved in the
solvent.  Then add the catalyst to this solution.  Mix well and use
immediately.  The cure time will be slightly longer than straight epoxy at
the same temperature.

Roger Pihlaja
S/V Dynamic Equilbrium


----- Original Message -----
From: "Robert Skinner" <robert at squirrelhaven.com>
To: "The Rhodes 22 mail list" <rhodes22-list at rhodes22.org>
Sent: Thursday, December 09, 2004 5:44 PM
Subject: Re: [Rhodes22-list] CB trunk Surgery - Roger's Recommended MOC


> Roger Pihlaja wrote:
> > ...
> > However, it turns out that uncured West system epoxy & catalysts (They
are
> > really epoxy products made by the Dow Chemical Co. - shhh, don't tell
> > anyone!) are completely soluble in ketones like acetone or methyl ethyl
> > ketone (MEK).  If Lou is not getting good penetration into the cement;
then,
> > he can thin out the uncured epoxy with acetone in practically any
proportion
> > he needs to get the viscosity low enough...
>
> I have a problem similar to the CB fix, requiring a
> saturation before adding mat, etc.  Questions, Roger:
>
> 1.  Does the MEK interfere with the catalyst action?
>
> 2.  Do you add the MEK after mixing resin and catalyst,
>     or before, to just the resin, or ????
>
> Thanks for any light you can shed.
>
> /Bob Skinner
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