Tony, ideally you need to aim to achieve a stable working environment
(workshop and airframe) temperature of around 25c.
Both the resin and the cloth benefit from storage in warm dry
conditions. If the cloth is old or has been left in a damp atmosphere,
the sizing deteriorates with a result that it will not wet-out properly,
you will recognise this by the white "dry" areas within the filaments of
the laminate. That is why the build manual recommends heating the cloth
storage cabinet with a low wattage light bulb.
If in any doubt, buy some new cloth (and never fold it as the crease
will "set").
Trying to wet-laminate with viscous resin is a pain and usually results
in heavy "resin-rich" laminations, you can warm it to thin it, but this
reduces its pot life -- also a pain. Most of my experience has been with
the SP Systems (now Gurit) resin and I found that the slower hardener
was far less viscous, giving the double benefit of a longer working-time
and much more satisfying to work with. Check the West Systems datasheets
to see if less viscous hardeners are available.
Lastly, if you need to use localised heat, do so with care. The gentle
warmth from a hair dryer is fine but the vicious heat from a hot-air gun
or paint-stripper will almost certainly destroy or distort the
work-piece. At best it can cause localised exothermic reactions, which
will render the job unusable.
The trick is to prepare everything the day before - warm the workshop,
lay out everything you need. When you've finished, drop the brush into a
pot of vinegar (much cheaper than Acetone) and just leave everything
alone (don't attempt to clean up - you'll just spread the goo over
everything. Just walk away. The next day when everything had dried, you
can clean up easily.
Good luck!
Nigel
On 22/05/2013 23:26, Tony Renshaw wrote:
om>
>
>> Hi, I'm laying up here in Sydney in temperatures that have recently tu
rned towards our winter. I'm using West Systems which already does not we
t out the cloth as well as the SP Systems, and has a shorter pot life, al
beit in warmer weather. I'm preheating the job area, the Lift Pin externa
l reinforcement lay ups, and mixing the resin and hardener under workshop
spotlights that generate a lot of localised heat. The glass cloth though
is cold, and I am wondering about placing it in foil in the oven to heat
it up pre layup. I even thought of microwaving it, when my wife isn't at
home. Any thoughts on the wisdom or otherwise of doing this? I want to m
ake the cold cloth as conducive as possible to allow ingress of the resin
into the individual fibres of a single thread, as I occasionally have ha
d some small splinter strait ions in these layups that appear to be micro
dry areas along certain fibres, but the matrix between them is fully wet
ted out. Thanks in anticipation.
> Regards
> Tony Renshaw
>
>
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