wrote in message
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Hello
I'm about to start refinishing a Discus.Searching through this and
other forums I've noticed people are leaning towards polyurethane and
away from gelcoat.Gelcoat seems to be much easier in my situation,
since I don't have a spray booth and they don't recommend sanding poly
after you've painted.I asked about PPG Concept locally and the dealer
says that acrylic urethanes shouldn't be sanded.Their top of the line
poly is called Deltron- but he couldn't say why it is better than
Concept.There's also DuPont with it's products- and they are 3-4 times
cheaper than PPG.I wonder if they really differ in quality that
much.Please advice.
Before the paint I'll have to fix one of the canopy hinges-
the rear one - it's delaminated and moves quite a bit.Pictures of the
crack are here http://picasaweb.google.com/barowicz/Canopy. How to fix
such a small detail? It seems that it takes a lot of stress and that's
why it's cracked.

Thanks,
LB

I'm looking at the same thing you are. I've been studying the options for a
couple of years.
I've decided that gelcoat is the better option for me. Take a look at Jim
Phoenix's site where he refinishes a Nimbus 3. http://www.jimphoenix.com/

Polyurethanes are wonderful materials that are very durable and last a very
long time. In this regard, they are better than gelcoat. However,
everything depends on surface preparation and priming. You'd better get the
prep right 'cause it's hard to fix problems after you shoot the final coat.
To spray polyurethane, you really need a profesional spray booth with
professional skills and tools. It can be repaired but it's best not to.

OTOH, gelcoat is a more forgiving process - easily sprayed and highly
sandable. The refinish process is relatively simple. Just grind off the
old white stuff, fix dings, fill and contour the surface, spray gelcoat and
sand/polish to the desired finish.

Note that minor 'orange peel' and/or runs in a freshly sprayed gelcoat
surface aren't a big deal since you plan to sand off most of the coat
anyway. If you really screw up a spot, just repeat the process for that
area. Try some small projects like gear doors first so you climb the
learning curve on out-of-sight parts.

To do it right you need a clean shop with reasonably controlled temperature.
Keep in mind that a refinish can be considered a 'major repair' which
requires proper paperwork and AI sign offs. It's especially important to
keep control surface weight and balance within the limits specified in the
maintenance manual. A owner/pilot is allowed to do anything to his aircraft
that an AI is willing to sign off. Find a friendly AI before you start.

Bill Daniels