Randolph wing walk gets soft and “melts”

[Rex Kwan Do]

Shot acrylic enamel paint on recently replaced aft wing walk panel on a PA28.

let the paint cure a day and then coated with Randolph wing walk. Let it sit 2 days. It held up fine and I’ve flown several times without issue. The coating seemed like it was working well.

yesterday I flew cross country and as I was putting the airplane to bed, I noticed what looked like a boot print (and the white paint underneath) in the wing walk. It looks like with the warmer weather (80F) that it got really soft and my weight was enough to tear the coating.

the wing walk had been properly thinner with toluene as per directions, all I did was lightly scuff the paint and then clean and apply.

Any thoughts? Do I try to clean up the damage and apply another coat? Would rolling this over fresh acrylic enamel paint cause a lack of adhesion?



Thanks for your help…

 

[Gary Ward]

Did you use activator/hardener in your acrylic paint?

It sounds like the the paint wasn't cured enough. Without hardener it will take more than 24 hrs to cure.

I would let it cure more, both coatings before trying to repair it.

 

[Bell206]

let the paint cure a day and then coated with Randolph wing walk. Let it sit 2 days.

Sounds like the toulene softened the uncured acrylic. Did you prime the panel before the acrylic? If so what type primer?

One day is not long enough for the base paint to cure/dry to handle a top coat especially when cut with an aggressive solvent like toulene. Perhaps discuss issue with an acrylic paint vender/shop to get options. But definitely dont add another layer of paint at this point. Unfortunately in my experience if the toulene "released" the original "bond" of the primer or acrylic your options will be very limited.

 

[Rex Kwan Do]

Thanks,

It was primed with zinc chromate from the mfg. sounds like I may need to be prepared to remove the wing walk that is unbonded, clean it up and reapply.

I’m new to coatings and thought I understood the dynamics. Clearly I didn’t know what I didn’t know but I won’t make the same mistake twice.

thanks for the insight.

 

[Bell206]

sounds like I may need to be prepared to remove the wing walk that is unbonded, clean it up and reapply.

You may still want to talk to someone with paint experience before moving forward. Without seeing the paint condition it sounds more like you'll have to remove more than just the wing walk to get to a good foundation. If the toulene "unbonded" the acrylic you may have to remove the acrylic and possibly the primer. Go to a parts store that sells auto paint and ask there.

 

[Gary Ward]

Acrylic enamel paint takes weeks to cure, a month or more. I have never sprayed it with out a hardener to chemically dry it overnight so I could mask it and paint a second color the next day.
Do you use hardener in your enamel paint?

 

[Rex Kwan Do]

Acrylic enamel paint takes weeks to cure, a month or more. I have never sprayed it with out a hardener to chemically dry it overnight so I could mask it and paint a second color the next day.
Do you use hardener in your enamel paint?

Yep the paint was mixed IAW the mfg directions including a medium reducer. The paint shop gave me the directions on application and timing for hardening. The “time for a second coat” was 16hrs which I went longer on. The white paint I shot appears intact underneath the wing walk compound. It’s almost like the wing walk compound just didn’t adhere to the white base coat.

at this point, aside from looking ugly, it’s not hurting anything so I’ll probably see if I can remove the areas that don’t appear to have adhered and go again once I’ve cleaned and prepped.

 

[Dan Thomas]

It’s almost like the wing walk compound just didn’t adhere to the white base coat.

The vapors coming off the still-fresh acrylic might have prevented proper cure of the wing walk paint.