Hi All,
This is my experience with filling / sanding / painting, on planes, boats, cars
etc....take it or leave it ????
Use the Expancell /epoxy system, as supplied by Europa, on all the control
surfaces.
These, ideally, should be post cured [ max 55C for 10 hours ] After the post
curing,
scrub the surfaces with a hot / strong solution of washing detergent [ Daz
/ Surf / OMO etc ] with a stiff scrubbing [nail brush ? ] Flush off all traces
of detergent with fresh water, and dry in your ''oven'' for a couple of hours
at about 30 C to totally dry out the surface. From now on, wear cotton gloves
when handling, so as not to contaminate the surface [ skin oil, peanut butter
W.H.Y?
Scuff sand the surfaces with 80 grit paper [dry] to remove the shine. Vacuum off
all the dust.
Fully mix some epoxy. Add the Expancell to the FULLY MIXED EPOXY, as much as you
can [or you get fed up with !] until the filler is like bread dough.
Mix up a small amount of resin, moisten the control surface with this mix, just
enough to wet the fibres, it will just be shiney.
Trowel on the Expancell, trying not to get any air trapped under, heavy pressure
with the trowel will normally ensure this. Fair in the filler as best you can,
but leave it well proud, by up to 1/4'', YES 1/4 OF AN INCH ! If the filler
has a ''sweaty shine'' to it, it was mixed too resin rich.
After a couple of hours, you can go back and smooth out some of the ''waves''
Put somewhere warm [or out in the sun] for a couple of days.
Take the surface outside onto padded saw horses, with your back to the wind, and
with a sanding board [3M do a nice sanding board with 40 / 80 / 120 grit paper
called Hook - it, about 18'' long by 2 1/2'' wide] sand with the board held
spanwise, moving in alternate 45 stokes along the surface , you will soon get
a smooth / flat surface, but too high.
Keep sanding until you see the first signs of the glass weave showing... STOP...
If you have mixed the Expancell dry enough, this sanding on a flap or aileron
will
have taken you about one hour, and you will have covered your neighbors car
with a fine layer of cream dust !
Filling the seams on the XS wings, and the fuselage, use the Expancell / epoxy,
but slightly wetter, so you just get the ''sweaty shine'' on the trowelled
filler.
As an example, two of us [Bill and myself] filled the seams on a pair of Motor
glider wings, and the Airbrakes and Ailerons, ready for the paint shop, in six
working days [12 man days]
Do not use Super fill, [ it is far heavier than a dry mix Expancell filler, it
is much harder to sand, it will sag on any vertical surface, it is very
expensive,
and it seems to iritate skin far more ] do not use Smoothprime or their topcoat.
Not impressed at all with those ! Use a barrier coat between the primer
and the topcoat. Ensure the topcoat has at least 97% Ultra Voilet Block. Use
paint product from a quality manufacturer, ie PPG,US Paint, etc....
Do not bother with colloidial silica, we did some ''blind testing'' with a
number
of people once, non could tell any difference, I believe the placebo principle
works here !
Do not muck about with all this fishing line nonsense !
If anyone needs further details on this subject, get back to me
Cheers,
Nev.
>>> "Fred R. Klein" <fklein@orcasonline.com> 11/07/03 04:39pm >>>
As I builder just now facing the task of filling, this current thread of
"filler" reminds me of an obscure typeface called "Threadfill" which is
fuzzy, wiggley, and difficult to decipher.
Don't get me wrong...I'm grateful to hear about so many builders'
experiences, and as a consequence, I'm hopeful to avoid pitfalls. And I'm
more than willing to apply the elbow grease and do whatever work is
necessary to get optimal results...nonetheless,
-I'm troubled conceptually with the notion of coating the wings and control
surfaces with as much as 1/4" of filler to be sanded and contoured which
would seem to run the serious risk of altering the airfoils with uncertain
results.
-I'm concerned with the comment that improperly applied filler results in a
surface which is too soft and vulnerable to dings in a fully-finished
airframe.
-I'm surprised to learn of the difficulties which apparently result in the
event that an initial coat of filler is found to be insufficient and
additional filler is required.
-And what is this "colloidal silica" and potential sources for acquiring
some?
Is there someone out there who can spell out "the way"...or am I, and others
like me, left to digest the instructions in the Europa manual with a grain
of salt and thoughtfully consider the various ways previous builders have
addressed this issue?
Would Neville or Andy be willing to stick their oars into this discussion?
a somewhat bewildered Fred, A194
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