Need advice for applying POR-15, especially in a cold garage.

Hi everyone,

I'm getting ready to start reassembling my suspension and fuel system on my car, and there are areas that could use a bit of paint to slow down some rust.

I've never used POR-15 or similar products before so I could use some advice on it.

For the most part I want to do some "spot application". Things like the brackets for my brake line junctions, some smaller rust spots on the chassis, etc. I don't intend to take strip the undercoating down to bare metal in large areas or paint complete parts, etc.

So I'm wondering how well POR-15 will work on this.

Will this stuff stick to old undercoating?

It is very liberally slathered all over the bottom of my rabbit and I don't want to strip it off clean to apply POR-15. I would consider a small area bordering the rust spot if it's necessary, but that's about it.

I'm also working in a cold garage in the Midwest. It's been an average high of about 20 degrees lately. I have a bullet heater, but I'm not expecting it to heat the garage up to an optimal temp for this stuff curing. I'll definitely get the garage warm beforehand and keep it running for 2-3 hours after I apply it, but I'm not going to run a bullet heater for 7 or 8 hours in my garage!

So with that said has anyone had experience with applying this stuff in cold conditions?

Would a heat gun on a low setting, blow drier, or heat lamp help it cure and expedite it drying? If so is any particular one better and less likely to cause paint wrinkling, etc?

I thought about warming the surface up with it before applying the POR-15, but I'm wondering if using it will it's drying would help too.

Assuming I won't really get the garage up to an "ideal temp", will this stuff still dry okay over a longer time period?

Will applying a smaller amount (i.e. just to cover a bracket or a surface rust spot) help?

If POR-15 is too tempermental for applying in cold weather, is there another rust converter that anyone would recommend?

What I did with Chassis Saver last winter:

Wire wheel until the surface is pretty clean of crud. Hit it with Pre and let it dry on its own. I left the can inside, painted everything, and then put it in a garage closet, which was way closer to inside-house temperatures to cure.

I think a cold-cure would be a bad thing, but I have no data or evidence to back that up. Everything I did this way stood up so far.

I painted my entire trailer wiht it, in a cold ish (30-40's outside with heater going, 50 maybe inside?) garage. It takes a couple days to get to a good hard cure, but gets there eventually.

My technique was wire brush the loose stuff off, and paint wiht brush. Worked great. Covers and sticks to more crap than it should. I don't know if it will really stick to undercoating, but I think if it flakes off that, the stuff stuck to the metal next to it will likely be fine.

Before

After

That was just brushing the loose stuff off.

Dont get it on your face, or hootus.

Thanks Java, glad to know that it still managed to cure. And it seems to have held up well for you since?

In reply to Contradiction:

Yes its great! I find it sticks to rusty/old metal much better than clean new stuff however. Ceran wrap under the lid, or it never comes back off.

java230 wrote: In reply to Contradiction: Yes its great! I find it sticks to rusty/old metal much better than clean new stuff however. Ceran wrap under the lid, or it never comes back off.

Awesome, glad to know it didn't give you any issues afterward.

A few non por15 specific cold weather tips, that might be worth testing out if you have the opportunity.

It helps with some paints (evaporative type) to bring the paint (and if possible part) inside and let them get warm. Then take them out in the cold and paint. Also just blowing a heat gun or hair dryer on the wet paint (or cold part) for a few minutes helps. Just move the air around, staying in one place can push the paint around. Generally thinner coats are better for faster drying.

jere wrote: A few non por15 specific cold weather tips, that might be worth testing out if you have the opportunity. It helps with some paints (evaporative type) to bring the paint (and if possible part) inside and let them get warm. Then take them out in the cold and paint. Also just blowing a heat gun or hair dryer on the wet paint (or cold part) for a few minutes helps. Just move the air around, staying in one place can push the paint around. Generally thinner coats are better for faster drying.

Unfortunately I'm pretty much trying to "spot treat" some visible rust on the chassis and the car is in an unheated garage so I can't bring it inside to warm up but I do plan on running the bullet heater in the garage for about 3 hours so the ambient temperature is at least better before and while I am painting.

I also plan on hitting the metal with a heat gun to warm up the temp before I do apply the paint.

I'm kind of curious to see if anyone has had experience with blow drying or heat lamps on it after painting it on. I could see setting up a heat lamp towards it to help it cure as long as it doesn't make it wrinkle, etc.

I'll probably try one small spot first to see how it does.

Bumping again since I might be testing this out this weekend. It's supposed to hit 40+ degrees on Sunday.

I've covered my car with a blue tarp that went to the ground and then covered that with a few moving blankets. Car was on jack stands and I had a little heater under the cover. Had the temp under there up to 60 plus with outside garage at a nice 28. Takes a day to get it good and warm. Even the cement was comfortable crawling around under the car. Like said above that stuff get's everywhere even places that you didn't paint. I've found it's best to remove all the flaky rust. Then clean back the paint and undercoating just enough to get to clean metal. Then once it's flashed paint it with something to cover it. Once it hardens it is about impossible to get paint of any kind to stick to it and not want to flake off after it's dry.

Just don't get it on your houtus...

NoBrakesRacing wrote: Just don't get it on your houtus...

Pirate4x4.com?

In reply to obrut:

Oldie but a funny.

I have a '79 BMW coupe that had a number of rust spots on the bottom. I "spot treated" with POR in a 50-degree garage, and it has held up just fine for two years now. That being said, I followed the prep instructions. A wire wheel to get off loose stuff. A careful degrease WITH a water rinse. Then their "activator" spray WITH a water rinse. For the water rinses, a good spray bottle is enough, but it takes a while. And then let it get bone dry before you paint it.

brad131a4 wrote: I've covered my car with a blue tarp that went to the ground and then covered that with a few moving blankets. Car was on jack stands and I had a little heater under the cover. Had the temp under there up to 60 plus with outside garage at a nice 28. Takes a day to get it good and warm. Even the cement was comfortable crawling around under the car. Like said above that stuff get's everywhere even places that you didn't paint. I've found it's best to remove all the flaky rust. Then clean back the paint and undercoating just enough to get to clean metal. Then once it's flashed paint it with something to cover it. Once it hardens it is about impossible to get paint of any kind to stick to it and not want to flake off after it's dry.

That's a great idea! I take it you just used a little electric space heater?