life of applied primer coat (MIL-23377) when being exposed to environement and sunshine

[ZeeS]

we have an aircraft that is to be preserved for some time in future. it was depainted for inspection. It has presently been primed with MIL-23377 primer.

the aircraft will remain exposed to UVs and sunshine alongwith rest of environmental factors. i do know that a top coat will endure around 4 years ((in case of parked outside) and 8 years (in case of parked inside)as indicated in USAF TO 1-1-8.

what life can we expect this coat to be of, while in open and in shade?

thanks in advance.

 

[CoryPad]

MIL-PRF-23377 primer is epoxy-based, which has poor resistance to ultraviolet radiation. You can expect this coating to chalk, degrade and fail within 2 to 3 years when exposed to full sunlight, maybe less depending on the coating quality and the sunlight characteristics.

 

[ZeeS]

thanks CoryPad....

 

[tbuelna]

Wouldn't the thickness of primer coating have an affect on the corrosion protection it provides over time? Normally, primers are designed for best adhesion and minimum film thickness. But this does not mean a thicker coating of primer could not be applied for use as a preservative. As noted, primers do not typically have the additives that topcoats do for UV resistance, etc. But as long as the primer coat prevents penetration of moisture onto the metal structure, it is performing its job, right?

 

[CoryPad]

Terry,

Yes, higher thickness usually improves corrosion protection over time. But that seems to be secondary to the issue here regarding epoxy-based coating exposed to ultraviolet radiation. The coating will be damaged and not prevent moisture penetration.