It's been a while...

After a long break from building (blame it on job change, life change, funding issues, there's plenty of excuses) I have been slowly getting closer and closer to the pile of airplane parts in my shop. Lurking around this site has been one key in getting me started in the right direction, so thank you to Doug and everyone here who makes this so much easier!

Today I actually moved the fuselage out of the corner of my shop where it was being ignored and piled around with other projects and items my friends can't fit in their own garages. There is an embarrasing layer of dust on a few of the flat surfaces, which serves to remind me just how long it's been since I did anything on this project. Unfortunately, the dust isn't all that needs cleaned off...

Apparently one of the feral cats that sometimes try and find a good hideout here managed to get in by squeezing through a sliding door at the rear of the shop and decided that my fuselage would be a great spot to mark his territory by spraying it down with a couple doses of cat pee! One shot on each side of the fuse up near the firewall, and one shot on the firewall itself.

I don't know how long it's been on there, but it must have been a couple months I guess (judging from the last time I saw a cat hanging around). I grabbed the mineral spirits and cleaned it off, but there are still stains on the aluminum. The stainless steel firewall cleaned right off, with no signs of staining. I tried acetone as well, but no luck with that either.

I knew I would have some questions when I got back into this project, but I didn't think my first one would be "How do I get cat pee off my airplane?"

Thanks in advance, and it's good to be back!

Roger Barnes
-9A QB, almost ready for finishing kit

Got any close-up pictures? My hunch is you're seeing some corrosion of the alclad layer, but it's impossible to know without seeing. I'm only guessing. I would imagine that cat urine is highly acidic and corrosive, though. You may need to scuff it with scotchbrite and spot prime to prevent any further deterioration until your final painting.

Yes, it looks a lot like corrosion...

After trying to convince myself it wasn't, I took another look this morning in better light and yes it appears to be light surface corrosion.

As I have not yet decided on a final paint product (actually haven't really considered it) I want to take care of this in a way that won't cause me any headaches down the road.

Will SEM self-etching primer in a rattle-can be compatible with most paint choices down the road? And considering the facts that my shop is unheated and the temps here won't be above about 35 for a couple months, will the primer even stick?

Thanks again for the help!

Roger Barnes
-9A QB, almost ready for finishing (after cat pee removal)

Cats: Why I hate cats?

I was finishing up my RV-7a project and was planning on flying it without paint. I kept my wings in a wing holder with the leading edges down. I built in a garage which I would commonly leave the door open for ventilation. Anyway I pulled my wings out and I saw stains on the leading edge like an acid. Turns out the cats in the neighborhood took turns marking their territory and with the cat urine mixing with the humidity, I had to paint my wings immediately or risk further damage. I talked to one knowledgeable person at a paint store and the only thing more corrosive than cat urine is monkey urine. They have a primate research center here and they have to face the cement pens with epoxy paint to prevent monkey urine from dissolving the cement pads.

My advice scotch brite the area with the urine stain/corrosion and prime it. When you scotch brite the area, your have taken the alodine coating off and the aluminum is unprotected. I put the wings after painting in the same holders with a vapor barrier to protect from the urine. The cats still got in and tried to do the same thing but the plastic and imron paint prevented further damage.

S S Anderson
Lafayette, La.
190 hours flying

I think we have a call sign for you. "Tom Cat" seems appropriate.

rrd1_99 said:

Will SEM self-etching primer in a rattle-can be compatible with most paint choices down the road? And considering the facts that my shop is unheated and the temps here won't be above about 35 for a couple months, will the primer even stick?

Click to expand...

Roger,

I think you'll find the SEM primer very easy to use and apply, even in cold temps. I wouldn't worry about compatibility with your paint choices down the road. When that time comes, a swipe or two with a cloth soaked in MEK will quickly remove the SEM primer.

Thanks

Thanks for the help with this. It's warmed up enough (mid-thirties!) to consider getting out to the shop tonight and taking care of this.

Roger Barnes
-9A QB, almost ready for finishing kit