More POR15 Q's...

[mudman]

I am refinishing my tandem axle trailer this week and have decided to use that magical POR stuff on all of the metal stuff. I have sandblasted all of the crevices an DA'ed all of the surfaces down to metal/light rust/thin paint. I am about to wire cup a couple of spots I couldn't DA and the sandblaster didn't remove enough crap. SO..... in about 15 minutes I'll be ready for metal ready.... but:
1) What kind of temps do I need to put the POR on?

2) How long can I leave the metal readied surface bare before PORing?

3) What if it is expected to rain tonight? Will the POR have set up properly in low 50F temps?

4) I've read about spaying primer while the POR is tacky, and plan to do this, but all I have is self-etching primer in a rattle can, is this cool?

5) This is a work trailer (it gets beat to hell), is top coating with rattle can gloss black regularly going to take care of UV issues?

I need to use this trailer this week so this project may wait until next weekend (also, hopefully sunny and warmer days). Thanks in advance for all advice!
-Jeremy

[joefrantz]

Jeremy:
I can help on a couple of your questions.

The idea behind the metal prep is light etching, and cleanliness -- especially grease. I would think that you could let it sit in prepped mode for several days as long as it was protected from water, oil, and not handled with bare hands. I would blow it off with compressed air to remove dust prior to application of the POR-15.

I can also tell you that POR -15 is very slow to set up even at ambient temps around 80 degrees. Its my main problem with the stuff. It stays tacky so long that it is a virtual dust magnet. Strictly from my own experience, I would not use it at anything less than 70 degrees.

Good luck.
Joe


ssand not haneao

[Gumba11]

Hey Jeremy,

I would have to disagree about the temp issue with POR15. I am in the final stages of a complete interior exterior restoration and I have used a ton of POR15 while doing it. Most of this work has been done in the dead of winter here in Portland Oregon where the temperature is regularly in the 40s and 50s. These were the very temps present when I applied most of this product. I have not had any problems with cure time. I found that in the coldest temps you would have a set product in around 3 to 4 hours.

I do not recommend you leave metal bare for more than a few hours. I have found that when I left parts of my project undone that were bare metal that they would be rusty by morning. Of course it is a little humid here in the winter time. If you leave it for too long then you will find yourself repeating steps you have already done. Never much fun to do things twice when they could have been done right the first time.

Just my .02, Hope this helps you out.

.................................................. .......C

[JohnJL]

I have only applied it in 70+ weather, it set up quickly.

Letting it sit after etching isn't a problem, just blast it with air before you paint. It likes a little rust, so if the parts add a little surface rust over a few days, all the better. But make absolutely sure it is completely free of oil and grease.

Hint: do the first coat in silver POR, then follow with black. That way you'll know you got EVERYTHING.

good luck. and wear tyvek and glasses. It gets on EVERYTHING and stick for weeks. Believe me, you'll be wearing it for a long time and it WILL blind you.

[mudman]

Thanks guys, that is what I wanted to hear. I wasn't to worried about grease because I was removing so much material, it is (was) really the rain that worried me. It looks as though today will be perfect if not a little cold (60F).

What about priming and top coating? Is the self etching primer ok to use? Is the rustoleum going to give UV protection?

I managed to cut and sand all of the wooden parts yesterday, this morning I'll be painting the wood stuff in the garage. Hopefully it stays sunny and gets a little warmer so I can post some finished project pics.
Thanks again!
-Jeremy

[mudman]

SOOOOoooo, I just checked weather forecast: 41F ! WTF, MI sucks.

What do you guys think about that kind of temp? I don't care if I get dust in the finish unless it will affect the strength/rust protection.

[Evans, Marv]

After you treat the metal with metal prep, I wouldn't bother with primer. POR-15 will adhere directly to the metal & that's probably the best. Painting it with an alternate color is a good idea to tell if you have painted over all of it afterwards. You can paint over it while its still a bit tacky. Getting a little dust on it won't affect the strength or rust protection. Getting good coverage is the important thing for rust protection. After it hardens, it will be like powder coating.

[mudman]

No no no, not primer before POR15 application, after POR15 application. The issue is that nothing bonds to POR after it is cured except their stuff, but others have mentioned priming while the 2nd coat of POR is tacky. My big question is:

***can I use SELF ETCHING PRIMER while POR is tacky?***

or should I use plain jane primer in a can. Self etching has stuff to help it bond to clean metal. Is the bonding stuff going to interfere with anything (since I believe it is meant to bond to metals and not POR coatings)? I know I'm being a bit picky but I like doing things correctly (everything except spelling and math).
-Jeremy

[Tim Hancock]

Just paint it after applying the POR, Rustoleum should stick to the POR just as good as the primer you were going to use. If it were mine I would brush or spray the rustoleum on as the rattle can Rustoleum stuff will probably not give you a very durable lasting finish. You did say this was a utility trailer right?

FWIW I blasted, then painted (no primer) (with a spray gun) a motorcycle trailer with Rustoleum 5 years ago and other than the black paint dulling a bit, it still looks great even though it sits out all the time in here in Ohio.

[mudman]

Awesome, that is what I wanted to hear, Tim. My local HD and ACO are out of rustoleum in nonaerosol so rattlecan it is (going to be covered mostly by wood so durabilty not really too much an issue.

Thanks a lot for sharing your experience with me, I don't like guessing...
-Jeremy