>>>I added silica
carbide to the Expandcell in a one to four ratio.
I assume you mean fumed (or colloidal) silica which is used for thickening a
resin
mix to give a creamy, non-sag consistency? Silic(on) carbide is used as a
filler to make ultra-hard wearing surfaces which would virtually need an angle
grinder to sand down!! It is also extremely high density!
Also when using silica don't use any more than you need to get the non-sag
properties
you want. Excess silica does make the final filler mix a bit harder to
sand and a bit more brittle.
As a manufacturer of epoxy resins (including the Ampreg 20 used in the UK kits),
we would suggest that there are alternative resins for filling and fairing to
Ampreg 20 which is primarily a structural laminating resin (hence its use in
the spar and the bits people fabricate themselves). Many people do use it for
filling to keep things simple and have one resin in the workshop, but products
such as SP106 (the UK equivalent to West System) are easier to sand as they
have lower structural properties (eg tensile/compressive strength and modulus)
and are a bit softer when cured. Both West and SP106 were originally designed
for bonding, filling and coating of wooden boats and so are also more tolerant
of lower cure temperatures and less than ideal (ie leaky boatyard!) conditions.
They are also a bit cheaper than Ampreg 20.
We have produced a guide to filler types and a suggested mixing table which can
be found as pdf's at:
http://www.spsystems.com/prod-ancill.htm
There is also a guide on to how to fill and fair boats (which is all very
similar
to aircraft). See the menu of application guides at the bottom of the following
page:
http://www.spsystems.com/techinfo.htm
and scroll down to 'Filling and Fairing'.
Hope this helps someone.
David
Europa Classic Trigear - GBWJH
-----Original Message-----
From: Paul McAllister [mailto:paul.mcallister@qia.net]
Subject: Re: Europa-List: resin for filling
Hi Paul,
I have pretty well just finished up the last of the sanding and filling on
my Europa. I took the best part of a year because I inter dispersed it with
more interesting tasks.
I started using Expandcell and West Systems epoxy resin. I added silica
carbide to the Expandcell in a one to four ratio. I mixed up the expandcell
until is was very dry and applied it to a surface that I had put a very dry
smear of epoxy onto. On balance this worked okay, but the dry mix was hard
to spread and had a lot of pin holes. I put it on fairly thick as to get it
on one coat, and being pretty dry it sanded easily. If you want to go the
West Systems route plan on using 2 gallons of resin. (I used one before
changing over)
I started having a bit of respiratory distress with the West Systems epoxy,
even days after it had dried I would find myself coughing in the work shop
so I changed to Polyfiber's Superfil. Now this stuff is expensive, but
really nice to use. I found that if I mixed it with a bit of gentle heat I
got no pin holes, and if I applied heat when I spread it, I could get a
really nice smooth layer. I also found that I could add a bit and find that
the batch to batch consistency was the same. One balance it was much nicer
to use, but at a considerable cost. I think I used two, three gallon kits
of the stuff.
Just my 2 cents worth. - Paul
----- Original Message -----
From: "paul stewart" <paul-d.stewart@virgin.net>
Subject: Europa-List: resin for filling
<paul-d.stewart@virgin.net>
>
> Now contemplating the task of filling and sanding. Can anyone give my a
rough idea of what sort of quantity of resin I'm likely to use (Europa XS
mono) if I use the standard filler supplied with the kit. Also have folk
stuck with SP systems (UK kits) or used other resin (I think some have gone
with west epoxy).
>
>
> Regards
>
> Paul Stewart #432
>
>
Visit SP at stand J06/L01 at the JEC Composites Show, Paris, 1st-3rd April 2003
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