Re: [Paddlewise] epoxy problems

Keith Kaste wrote:
> 
> I am building a stitch and glue boat these days.  I have gotten to the
> point where I am fiberglassing the hull.  The epoxy (West Systems) is
> not behaving the way I remember it during the warmer months.  It is much
> more viscous when I'm mixing it.  It gets really white.  I thought that
> since the temperature is less, the pot time would be noticeably longer.
> It is not.  Furthermore, it doesn't take long before it starts turning
> my boat milky white with each stroke of my foam brush.  Does anybody
> know what is causing this?  Is there a better epoxy system to be using?

The clues you give suggest that the epoxy has "separated" slightly,
owing to long storAge at a low temperature.  If the containers are
reasonably transparent, examine both hardener and resin with a strong
light behind the containers and see if you can spot any separation.  A
flashlight down the throat if you have an opaque container may do the
job, also.

If it has separated, incubate it for several hours in warm water (100F),
stirring occasionally.  It will remain well-mixed for quite a while
unless you let it get very cold again.  The best solution is to keep
both hardener and resin in a heated plywood box.  I used a 75 W light
bulb to keep such a box warm and it worked well.  For reference: I found
80 - 90 F was ideal for System 3 resin/hardener (I used
2:1::normal:fast, though fast hardener is OK to store at that
temperature).  YMMV

> Also, I'm seeing an oily film on the epoxied surface 24 hours after it
> has set up.  I am assuming this is the dreaded "amine blush".  I have
> not seen this phenomenon before. I used a scratch pad and water to get
> it off.  That seemed to work.  Some kit companies say you don't have to
> sand between coats if you don't wait longer than 2 or 3 days.  Is this
> accepted practice?  Does it apply in all temperature and humidity
> conditions?

If the blush does not disappear on clearing up the separation problem,
something else is wrong.  Check your mixing devices.  Small volumes are
notoriously difficult to measure accurately, especially if the epoxy
ingreds are cool -- they stick to the container walls badly.  Switch to
weighing the ingreds into a single container:  resin, then hardener. 
Very easy to control the mix that way.

P.S.  Keith, it may be uncool to double post to both Paddlewise and to
Wave~Length.  I suspect we should ask Jackie and Howie (thank you Alan)
about that.  Different, identical posts are probably OK, if I understand
the etiquette properly.

-- 
Dave Kruger
Astoria, OR
sea kayaker -- and chemist
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