POR-15 rust inhibiter

[lowNslow]

Has anyone used POR-15 rust coat/inhibiter? I was thinking of using this on my gear legs and was wondering if there would be any downside to using this product. It appears it might go on a little thick so may make it difficult to inspect for cracks.
http://www.por15.com/prodinfo.asp?grp=SSK&dept=1

[Bruce Fenstermacher]

Karl

I have used the POR products including POR 15.

The good news is that this stuff is TUFF. The bad news is that this stuff is TUFF. What ever yo get it on it will be on for ever including your hands and any equipment you use to apply it. The POR folks do not recommend spraying this stuff and I agree. It does actually go on pretty nicely with a brush.

Again what ever you put it on you WILL NOT GET IT OFF short of a grinding wheel and that will take a long time.

POR-15 will break down under UV so it has to be top coated. Actually UV and time is about the only thing that will effect it. Not all paints can be used on top of POR-15 so check that out first.

Another problem is the shelf life. Basically once you open the quart can you need to use the paint. It hardens when it is exposed to moisture. So just opening the can starts the process that can only be slowed down but not stopped. Oh and if you put the lid back on the can without a piece of cellophane between the can and lid you will NEVER get the lid back off.

A friend who had an auto restoration business used it for undercarriages and other areas of the cars he restored. Before he knew better he took a quarter and using a drop of POR-15, glued it to his dirty garage floor in the middle of a high traffic area. The quarter was stuck there until he moved and we used a chisel to remove it damaging the concrete floor. This stuff is tuff.

Is it right for a landing gear? It could be perfect if you never plan to remove it to insect the metal. And another thing is the paint tends to have some thickness filing holes. If you need the holes for a bolt you will be drilling them back out. In fact a variant of the POR-15 product is used to seal gas tanks with rust holes. And it works.

Though I did use a PRO-15 product on some of the interior wing parts of my Cub I probably wouldn't do it again. I like the POR-15 products for a lot of things, I'm not sure airplane parts are one of them.

Did I mention this stuff is TUFF and must be treated with respect.

I'd use a two part epoxy which is much more of an excepted practice on airplanes.

[lowNslow]

Bruce, thanks. I was wondering if this stuff might be a little to heavy duty, but then again, it would be nice to have something that wouldn't chip on the leading edges.

[GAHorn]

I'm thinking of the flexing which the landing gear does under normal useage. If the stuff cracked...it'd be difficult to remove/repair if I read Bruce's comments correctly.

There's another warning about these landing gear legs. According to Cessna, paint strippers cause hydrogen embrittlement in them which makes them crack and fail. If you strip your gear legs using paint stripper, you might want to bake them. (350-F for four hours should do it.) Then prime and paint them.

[lowNslow]

The POR folks do not recommend spraying this stuff and I agree. It does actually go on pretty nicely with a brush.

Actually, they have spraying instructions on their web site.
"SPRAY APPLICATION:
Use 30-35 lbs pressure for normal gloss. Reduce pressure for lower gloss (20-25 lbs). Thin only with POR-15 Solvent, if necessary, but do not thin more than 5%."

[Bruce Fenstermacher]

Yes Karl I know they tell you how but they also don't recommend it. Any over spray is not coming of anything it gets on. It takes about a week to wear off your hands.

i wouldn't be worried about how heavy it is. I used their silver POR-15 on the Cub wing parts. When it's fresh and I mean when the can is first opened it is very thin and goes a long way. It is also flexible and can take a beating. They have pictures of this on their site. When I said it was tuff I didn't mean it wasn't flexible. In fact that is what might make it so difficult to remove.

After the second or third time you open the can the paint will have gotten thicker. Still usable but then you will get a thicker coat and the brush lines don't flow out.

Buying it is small quantities is the way to go and there is a reason they sell it that way.

Like I said if you never want to remove it it might be the perfect paint.

I would use POR-15 in my battery box and I would use their exhaust paint on my exhaust if I cared what they looked like. I would use their gas tank sloshing sealer if I needed to seal a tank. (And I have but not an airplane tank yet)

I stopped using it just because it was difficult to remove. I would not ever spray it unless I was willing to through away the spray equipment and had the correct breathing apparatus and in a place I didn't care where the over spray went.

And another thing is no aviation people ever heard of it and while I like to be a renegade I decided I didn't need to be a paint tester on my airplane parts. It is just to easy to use the proven 2 part epoxy stuff.

[hilltop170]

I saw a C-195 that had black paint-on truck bed liner stuff on the leading edges of the landing gear to prevent chips and nicks. It looked good but don't know how hard it is to deal with.

[lowNslow]

I'm thinking of the flexing which the landing gear does under normal useage. If the stuff cracked...it'd be difficult to remove/repair if I read Bruce's comments correctly.

There's another warning about these landing gear legs. According to Cessna, paint strippers cause hydrogen embrittlement in them which makes them crack and fail. If you strip your gear legs using paint stripper, you might want to bake them. (350-F for four hours should do it.) Then prime and paint them.

Thanks George, now I need to find a oven big enough. By the way, do you know when ball peening is required? Would this be required after heat treating?

[lowNslow]

And another thing is no aviation people ever heard of it and while I like to be a renegade I decided I didn't need to be a paint tester on my airplane parts. It is just to easy to use the proven 2 part epoxy stuff.

I guess my only problem with the 2-part epoxy is that is what is on the gear now and it is rusting through. I was hoping to find something a little TUFFer.

[GAHorn]

...By the way, do you know when ball peening is required? Would this be required after heat treating?

I'll bet you mean "shot-peening". The leading edges/lower surfaces of the landing gear legs were shot-peened to harden them against FOD/rocks/etc. damaging the gear legs, which might set up stress-risers. Unless your gearlegs have been annealed (and the baking at 350-F would not be sufficiently hot to affect that) or unless your gearlegs have been damaged and subsequently re-bent/re-shaped and need hardening after annealing, then it's unlikely they'll need shot-peening. (I've got that process/specification somewhere... I need to find it and post it so that the info will be saved for posterity. When I do I'll post it in the MX Library.)

[lowNslow]

Thanks George. Yes, shot-peening is what i was thinking.

[GAHorn]

...By the way, do you know when ball peening is required? Would this be required after heat treating?

I'll bet you mean "shot-peening". The leading edges/lower surfaces of the landing gear legs were shot-peened to harden them against FOD/rocks/etc. damaging the gear legs, which might set up stress-risers. Unless your gearlegs have been annealed (and the baking at 350-F would not be sufficiently hot to affect that) or unless your gearlegs have been damaged and subsequently re-bent/re-shaped and need hardening after annealing, then it's unlikely they'll need shot-peening. (I've got that process/specification somewhere... I need to find it and post it so that the info will be saved for posterity. When I do I'll post it in the MX Library.)

By the way.... I had already posted the process. It is under paragraph 1(a) in the MX Library, http://www.cessna170.org/phpBB2/viewtopic.php?t=4973

The specification for shot peening is to be: Almen intensity of 0.012 to 0.016 with 330 steel shot.

[lowNslow]

Thanks George. Would a shotgun with birdshot do the trick.

[GAHorn]

Only if it's intended for waterfowl. (steel shot)