Hi All,
As discussed on the phone Dave, here is my take on the subject, not all wil
l agree, but look at the results of the contributors before you decide how
to progress ? [ and see how it fares after 5+ years in service ?]
Wash the surface with a hot / strong solution of washing powder [ DAZ / SUR
F / OMO etc..] as hot as you can stand, don't get the surface too hot, just
scrub the hell out of it with a scotchbrite / nail brush and flush it all
off with fresh water.
LET IT DRY, Out in the sun or in a hot room for 2 or 3 days.
Scuff sand the surface to get all the shine off, go with the weave directio
n to get down into the valleys, fold the paper [ 80 grit] to a knife edge t
o get right in, vac' off all dust. DONT TOUCH IT WITH BARE HANDS FROM NOW O
N ! Have a pair of new cotton cloves to hand [ pun not intended !]
Keep the Expancell in a tin [ sweet / biscuit tub ?] and dry out any moistu
re with a session in a warm oven [ as it is running down from a cooking ses
sion.]
DO NOT USE TIME EXPIRED RESIN !
In the UK, we are stuck with Ampreg 21 for structure [ it is cr*p ] but for
filling we are not tied to it. If you have Ampreg 21, use it, if you need
to buy resin, go with West .
Mix the resin / hardener fully, add the dry Expancell until you don't think
you can get any more in [ best to have a helper mixing for you as you get
on with the prep' and filling ?] It should be so dry, like bread dough, you
will be nearly able to pick it out of the mixing bucket. Make a note of we
ight of resin to volume of Expancell for future batches.
THIS BIT IS IMPORTANT !!! Mix up a new small batch of resin, and with a sho
rt [ cut off to 1/2'' long bristles] brush, scrub the mixed resin onto the
surface, just enough to make it damp / sticky, a bit like sellotape.
Dump and force down REALLY HARD the Expancell mix onto the damp surface,wit
h your favourite squeegee, the wet resin on the surface will fuse into the
lean Expancell mix, and allow the Expancell to stick to the surface.
If you can get the Expancell mix to stay on a dry surface, the mix is too
runny, it will be heavier and harder to sand. If the lean Expancell mix won
't stick to a dry surface, [like frozen butter on fresh bread] but does sti
ck to the moistened surface, you have it about right !
Don't piss about with fishing lines / profile gauges / lasers or any other
black magic. Whack it on once and thick. Force it down VERY HARD WITH YOUR
SQUEEGEE, this will get it into the weave, and get most of the air bubbles
out [ later to haunt you as pinholes !] Get it filled too high, try and cra
ft it smooth, but don't drag it about too much as you will pull it off agai
n.
If filled too high ONCE with this lean Expancell, after full cure, a WEEK a
t 25 + [ no good this time of the year, I fog a black trace coat over it an
d leave it out in the sun for 2 or 3 days in the summer], it will sand like
dense balsa wood. Sand it down gently to profile, try not to overshoot too
low.
If you don't fill it high enough in the first place, and you have to re vis
it the filling procedure, odds are the mix ratio of Expancell / resin will
be different, and when you try to blend in the 2nd batch,[ which won't be a
s well cured as the 1st batch] you will get a ''tide mark ridge'', which ma
y need filling with a third batch, which will give you a double tide mark..
.....
Other personal views, don't use ANY of the Polyfiber products, don't want t
o get sued by them, but I wouldn't fill / paint my Dustbin [Garbage can] w
ith them. Their blue s**t filler is much heavier than lean Expancell, doesn
't stick as well, burns your skin if any of the sanding dust gets on you, c
osts more, and if later covered by their paint, it will fall off at worst,
or end in micro blisters all over at best !
Stay with Expancell up to profile stage, seal with PPG Barrier Prime, then
if you are lazy, you can switch to polyester stopper for the PINHOLES ONLY
[Dolphin Glaze by Upol is good], reseal with Barrier Prime before the prime
r surfacer and Topcoat[UVR] ALL PPG.
Topcoat will not hide any defects, it will highlight them, the surface need
s to be perfect before you hit it with Topcoat.
Use 3M products whenever you can, best results per =C2=A3 / $ [ abrasive p
apers, masking tape etc...] The 3M ''HOOK - IT'' sanding boards and strips
are very usefull.
Pad the bench with pillows / foam to rest the surfaces on,padded weights an
d / or webbing straps will tame the movement. Make up a heavy 36'' x 5'' x
3'' sanding block from plywood that 80 grit can be stapled to, so you can s
and in a +/- 45 action to the span to get the profile without manufacturing
''dips''. Fog a light coat of black aerosol over the Expancell before you
start sanding, to give you a guide as to where the highs are, if filled hig
h enough, you will get the correct profile just as the weave starts to sho
w through at the ''high'' areas of the surface ? Take it outside, with your
back to the wind when sanding !
Have fun ! [No, there is only so much sanding in any one person, I reached
that about 3 planes ago, so I won't anymore! ]
Cheers,
Nev.
-----Original Message-----
From: G-ODTW <dave@robotas.co.uk>
Sent: Sun, Jan 6, 2013 7:44 pm
Subject: Europa-List: Re: Filling/Painting Classic wings & Tail. SUPERFIL?
SP106?
Thanks to everyone for your advice on tailplane filling. I have spoken to N
ev
yre, and I think I can now see how to progress.
--------
avid Walters
1474 816817
ave@robotas.com
ead this topic online here:
http://forums.matronics.com/viewtopic.php?p=391712#391712
-= - The Europa-List Email Forum -
-= Use the Matronics List Features Navigator to browse
-= the many List utilities such as List Un/Subscription,
-= Archive Search & Download, 7-Day Browse, Chat, FAQ,
-= Photoshare, and much much more:
-
-= --> http://www.matronics.com/Navigator?Europa-List
-
-========================
-= - MATRONICS WEB FORUMS -
-= Same great content also available via the Web Forums!
-
-= --> http://forums.matronics.com
-
-========================
-= - List Contribution Web Site -
-= Thank you for your generous support!
-= -Matt Dralle, List Admin.
-= --> http://www.matronics.com/contribution
-========================
|