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-   -   Any reason not to prime inside and outside of skins at the same time? (https://vansairforce.net/community/showthread.php?t=179499)

GPV 02-13-2020 04:56 AM

Any reason not to prime inside and outside of skins at the same time?
 
Hi all,

I'm wondering if it would be ok to prime the inside and outside of my skins in one go. I haven't seen anyone do this but it would help ensure the skin is primed under the rivet head. The plan would be to prime now with Stewart Systems ekopoxy, assemble the plane then sand lightly and topcoat in a few years.

Any reason why this shouldn't be done?

Cheers,

Greg

andrewtac 02-13-2020 05:29 AM

That is what I am doing, part of the reason was I have an older kit that had some corrosion that needed treatment.

PaulvS 02-13-2020 05:51 AM

Pro and con
 
Some 2 pack epoxy primers must be top coated soon after spraying otherwise they get too hard for the topcoat to stick. The spec sheet for Stewarts should specify any time limits.

Another issue I can think of is the primer will pick up oil and grime over time in the shop so it will very likely all need degreasing before topcoating.

The method I am using is to prime the insides of the skin wherever there are overlaps and contact with ribs etc. On the skin outsides I initially spray a line of primer along each rivet line and assemble. Then for final painting, scuff and degrease the whole thing, prime and topcoat. This ensures edges and rivet heads get primed.

I have heard though of some builders who have primed everything right at the beginning before they start assembling, it would save a lot of time.

daveyator 02-13-2020 06:44 AM

Make sure you know exactly what your final paint finish will be, or you may be paying your painter to remove all that primer. Not all paint systems are compatible with whatever primer you may be using. Search the forums. Lots of info available.
I seem to remember a similar question coming up only a couple of months back.
Cheers, DaveH
120485

rocketman1988 02-13-2020 06:47 AM

You mean
 
You mean it woul add a lot of time..

I primed only the inside of the skins and about every other part. It took tons of time. After some consideration, I can say that if I build again I probably would not prime. Do you want a 75 year aircraft or a 100 year aircraft?

Desert Rat 02-13-2020 07:04 AM

One big consideration would be if you're planning to eventually do the top coat yourself or hire it out.

I doubt that you'll find a paint shop that will warranty their work in that situation, unless they strip all that home brew primer off and go from bare metal with their process.

fixnflyguy 02-13-2020 11:38 AM

What I do
 
I primed the inside only while building. The most important part of priming Alclad is the "edges" including the inside of the holes. I use a smooth foam roller to prime inside surface of the skins( slightly thin the primer), and it will coat the inward protruding dimple edge. No mess, easy to do. Done correctly, its hard to tell it wasn't sprayed. When it comes to doing the final paint, I can bet your painter will want bare metal if he is looking to warranty the life of the paint...I painted mine myself, but I have painted several planes and like to start from bare metal.

cderk 02-13-2020 02:44 PM

Quote:

Originally Posted by rocketman1988 (Post 1407556)
You mean it woul add a lot of time..

I primed only the inside of the skins and about every other part. It took tons of time. After some consideration, I can say that if I build again I probably would not prime. Do you want a 75 year aircraft or a 100 year aircraft?

I would second that sentiment... it added way too much time and hassle. I'll be long gone before the plane.

GPV 02-13-2020 02:56 PM

Thanks very much for the advice everyone!

I have to admit, the more I think about it the more I lean towards not priming at all. I'm not organised enough to do big batches and it really is slowing me down. Probably better to finish more quickly and enjoy sooner rather than having it last long after I am unable to fly.

Kyle Boatright 02-13-2020 03:53 PM

Quote:

Originally Posted by cderk (Post 1407720)
I would second that sentiment... it added way too much time and hassle. I'll be long gone before the plane.

I?ll third the sentiment. I might rattle can zinc chromate the faying surfaces on the next one.


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