Poly Over Gelcoat

[James Lee]

I am looking for my first glider. Someone has a glider for sale that was built in the 70's. He sanded the old gelcoat and painted over it with poly.

Are there any major potential problems with that?

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There are Huge potential problems; Their extent and severity depend upon:

1) The condition of the gelcoat prior to poly topcoat. If it was crazed/cracked prior to topcoat and was not removed, the cracks will eventually propagate up through the poly.

2) The skill, knowledge base, and integrity of the operator who did the job. The task is highly operator-sensitive. Unskilled and/or ignorant and/or unscrupulous operator = a huge potential problem down the road.

Even some famous, purportedly reputable shops have "refinished" gliders by scuffing up the 100% crazed gelcoat, blowing on a ton of primer, followed by another metric ton of gelcoat or poly. AS-W20's, -19's and LS-4 an -3's have been the largest numbers I have personally observed. There was a cottage industry surrounding the refinish of these types 10+ years ago due to the crap gelcoat the Germans were using in that era.

These "refinished" gliders can appear fantastic for "a while" which could be a couple of years to more than 10, based on the 5-6 ships I have seen that were refinished in a suboptimal fashion. In my experience, there is no way to determine the quality of the process without invasive procedures; an excellent surface condition that is less than 5 or more years old in no way reflects the long-term durability of the finish. If it has lasted "a while" (see above), it is "probably" OK.

You either:

1) Trust the operator or someone who observed the entire process implicitly or .....

2) See photographs of the ship at each step of the process that are of sufficient quality to assess the surface condition. Note: these photos are difficult to shoot and the airframe is a lot of area. They need to be evaluated by an expert.

3) Offer a price of what a refinished ship is worth, less the some percentage of what it costs to refinish the ship in a reputable shop.

4) Roll the dice and buy it based whatever data you have. A modern reputable operator should have masses and mass balance measurements for each piece of the airframe pre- and post refinish. If there is a large weight gain or there are mass balance issues, or no data, pass. There should be photos of the process,a materials list, and a sign-off by an A/P or IA, whom I would want to speak with.

[K]

On Friday, November 16, 2012 7:11:07 PM UTC-7, James Lee wrote:

> Are there any major potential problems with that?
The big major potential of course is having to start over. This is very labor intensive (Expensive). Not so funny story; A few months ago I went 2/3rds across the country to look at a late model ship that had been refinished so poorly that I would not have flown it in its condition due to ballance issues on the control surfaces(It had been advertised as "Excellent condition" on WW). That said, Ive seen refinish work by experts and amateurs that has been excellent. If you don't know what you are looking at have a pro or a reputable shop do a pre-purchase inspection.
One thing to remember, Gliders live a pretty hard life. They are typically flown from dusty unpaved remote strips and landed out in all manner of rough fields. Constant assembly results in at least some hangar rash. In other words, don't expect anything perfect from that vintage. Good luck.