Blistering of Finish

Having observer the shrinkage in a 5 year old ASW 27
and 28, bear in mind there are no perfect 30 year old
gliders. put the wings in a plastic tent for 2 weeks
with a dehumidifier and the blisters will probably
disappear.

although i prefer gelcoat for repairability, in strong
uv conditions automative paints last longer, it is
quite possible that nothing much will happen to the
LS3 for 10 to 15 years

I have 1 glider which lives in cool and damp conditions,
the fuz was sprayed with paint 20 years ago after a
major repair , mostly over gel, no primer, still there
with a few blisters. Another, part but not all of the
gel was removed fom the tops of the wings and a thin
coat of new gel applied, 10+years ago. the old stuff
shows at the edges, but most is shiny and white (I
have regelled lots of other bits of the glider, some
bits have small blisters after a year, possibly because
the gel is to thin).

sounds like you have an honest seller, you have to
be realistic. gusssing the price range you will spend
a lifetime looking for the perfect glider

Pete

At 06:48 23 December 2007, Uniform Zulu wrote:
I'm looking at purchasing an LS-3 but the owner has
noted that the Urethane finish has blistered in several
places on the tops of the wings (The glider was re-finished
in 1996). According to the owner they are very small
blisters which have left pin sized holes. I'm assuming
that this would be caused by mositure which has made
it's way below the paint? He says the trailer is dry
and has a soler vent so I would assume humidity in
the air has caused the problem? and not moisture on
the surface.

What are the implications/underlying problems of the
blistering? and could I fix this easily or am I looking
at sanding down/re-finishing the entire surface of
wings again in the near future?

Any advice would be appreciated.

On Sun, 23 Dec 2007 22:58:15 +0000, Peter Thomas wrote:

although i prefer gelcoat for repairability, in strong uv conditions
automative paints last longer, it is quite possible that nothing much
will happen to the LS3 for 10 to 15 years

I owned a glider for over 10 years which the previous owner had sprayed
polyurathane over the gelcoat. Repairs of small scratches and dings are
not a problem.

- Firstly clean off all the wax with acetone.

- Then sand out the damaged area.

- Brush with polyurathane primer (this is a thick coat which builds up
like gelcoat). You may need a number of coats. If you use quick drying
"hardener" in the polyurathane, the paint on the wing drys faster than
the paint in the cup gets hard. If you put the wing in the sun you can
paint a number of coats with it, waiting for each coat to set before
applying the next, before the mix goes off in the cup. You need to build
up enough material to facilitate the re-finish.

- Wait for the paint to harden fully. (8 to 24 hours).

- Sand (wet) to restore the profile. You should end up with a perfectly
finished job, except the repair will be yellow and the wing is white.

- Now spray the yellow with a coat or two of aerosol "appliance white"
spray paint. That goes on very thin and drys very quickly.

- Then can carefully wet sand the aerosol with 2000 grit (just a few
strokes or you will go right through the very thin layer), buff and
polish and the repair becomes invisible. (If the job is not 100% you may
get a brown "water mark" around the sprayed area - normally due to wax on
the wing, but even this is very easy to ignore and virtually
unnoticeable).

Currently I have a share in an LS3a that has gell coat which requires a
re-finish. I would never consider re-finishing a glider with gell coat
instead of PU, and I would not buy a new one without PU. If the factory
price for PU was not reasonable I would get it sprayed after market,
before the gell coat starts cracking up and needs heavy sanding.

If the refinish job on the original poster's LS3a was done properly, I
would gladly swap his blistering PU for our cracking gell coat. (But not
the rest of the glider, we have a totally sorted out instrument panel,
new chute, decent Komet trailer and lots of little things that make it a
very nice glider....).

Ian

I painted my Apis 13 kit with Prestec. I think this is referred to as
a "gel-coat" but is really just a thickened polyester high gloss top
coat. The stuff sprays easily and wet sands easily too, and it is not
that expensive.

But..............it seems really prone to the blistering that everyone
is talking about. These are not particularly large, somtimes they
appear as a sheen if you look at the wings at the right angle, in
other places they are maybe a mm in dia and .003 tall, true bumps. The
first time I noticed them was after the first winter it was painted;
we pulled the sailplane out of the trailer, and the L.E. of the wings
were covered with them, luckily the smaller version of the bumps. I
unfortunately have no place other than the trailer and the outside
ramp to store the glider, and there is no electrical source for a
small heater or de-huminidifier in the winter.

The "good" news is these bumps mostly dissapear by mid-spring. Luckily
only a small portion of the airframe has them, and they seem to be
random as to where they show up. Guess at some point I'll have to
bring everything home and spend a winter sanding and re-painting.

Happy Holidays everyone.

Brad
199AK