POR-15 where to stop???

[JOeyKnapp]

So far I have stripped all of the under the hood metal and done the Marine Clean, Metal Ready and POR-15 paint on my sprite. I have just replaced the two lower a pillar metal pieces (hinge side, front side) and did the process to the inside of that box. I am starting on other areas of the car and was wondering what parts DON'T need that process?

I would be fine doing the whole car, but areas like the top of the cowl were completely rust free. I think I might be concerned about the buildup of POR-15, Primer, Paint and making clearances be an issue in some spots (although it doesn't seem like there are ultra tight clearances anywhere on the car that I have found yet..).

Any words of wisdom or advice? In the back of my mind I keep hearing the old adage about flossing your teeth "You only need to floss the ones you want to keep" and that gets translated to "You only need to POR-15 the pieces you want to keep"..

 

[dklawson]

In general, do not apply POR to smooth, intact metal surfaces. It doesn't adhere well to them. You would need to sandblast or heavily acid etch to get the POR to stick well.

Limit your use of POR to the places where there was rust and a rough surface was left behind after treatment.

 

[JOeyKnapp]

Any place I would POR-15 paint I would do the metal cleaning and metal ready (the acid that etches)..

I was thinking the whole underside of the car, the rockers, under hood, floor pans, boot..

 

[Gerard]

Before opening the can...

 

[JOeyKnapp]

Gerard, I am all ears if you have some insight on other alternatives... (or eyes as the case may be..)

 

[Gerard]

I do... will get back to you with more info.

 

[JPSmit]

I do... will get back to you with more info.

Gerard, if possible, please post this for all pf our benefit as opposed to a possible PM. Thanks!

 

[Gerard]

Sorry guys, was going out and didn't have time to elaborate.

First, let me say I personally don't believe in painting over rust. Anything I paint is cleaned to bare metal and metal prepped/etched.

I painted some suspension parts with POR product a few years ago. The parts were clean, fresh, bare metal. I wrapped and packed them in a box and put on them on my shelf in my garage. My garage is the lower floor of my home, so well protected from the environment. A year later, I pulled them off the shelf and discovered there was surface rust developing under the paint. I had to strip off all the paint (which wasn't that hard to do) and start over. I decided to try a product called Rust Bullet. The paint is much more durable and abrasion resistant. It comes in silver color only and is not UV sensitive. It can be painted over or left as is. They also make a chassis black that I also found very durable and it looks great. Both are rock hard when dry. In fact, if the product skins over in the can, you will need a hammer and chisel to break through it. The drawbacks are it's very heavy bodied and not readily sprayed. I find it is best applied with a foam brush. Forget cleanup, you will be trowing away anything you use with it. They claim it can be sprayed, but you'd need a large nozzle and I'm guessing fairly high PSI. They don't recommend thinning it. Their web site has side-by side comparisons for durability against similar paints. I find it's great for suspension parts and anywhere you want exceptional chip resistance. Good also in areas you don't necessarily want to topcoat. It can be used anywhere however. The biggest drawback is that it doesn't keep very long in the can once it's been opened. After 2-3 months, it'll develop a 1/4" or more skin, even if well sealed. The air in the can is enough to keep it curing. The only other drawback is if it's applied a little too thick, it tends for form little eruptions on the surface from the solvents trying to escape through the surface. (solvent popping)

Another product I like is called Zero Rust. It's also available in quart cans, but also in spray cans. I buy it by the quart and spray it with either a detail or HPLV gun. It comes in about 8 colors and is great for a primer coat before undercoating, but again, it can be sanded and top coated or left as is. It can be thinned slightly for spraying and cleans up with lacquer thinner.

Lastly, while not technically a rust preventive per se, I like Raptor bed liner. it's tint-able and because it's catalyzed, sets up very hard and durable. The texture gives a similar look original undercoating, but unlike rubberized undercoat products, it won't chip or dent and you can match it to the finish color you are painting the rest of the car.

Pix below show Zero Rust as a primer and Raptor bed liner over it, tinted Iris Blue. Some areas were masked off and painted with the finish color (no bed liner coating), so you can see how well the tinted bed liner matches the paint color.

 

[dklawson]

VERY nice and great information!

JoeyKnapp, the normal etch developed by the Metal Ready is marginal for preparation of bare metal when using POR. If you decide to use POR, use the metal ready several times to develop a deep etch. It is important to provide a good tooth for the POR to anchor to.

 

[apbos]

Gerard
I was going to use Raptor liner inside and under my car (where the original under coating was). However, I can not be sure as to what areas were originally undercoated. I believe all wheel arches and may be the area of the "shut panel"? Can you confirm this.

Regards
Paul

 

[Gerard]

Gerard
I believe all wheel arches and may be the area of the "shut panel"? Can you confirm this.

Regards
Paul

Hi Paul,

Yes, the complete wheel arch in the rear with some overlap around the edges, but if I remember correctly, I think only the rear portion of the front inner fender with some overlap on the side and upper inner fender. The underside was not undercoated. I shot the complete inner fenders all around and the complete underside, I masked of the front and rear spring mounts/perches, and frame legs forward of the floor pans.

Make sure when you shoot the stuff, you either cover your floor for a wide area or have some large sheets of cardboard to stand up an the edges of perimeter. That shutz gun will send stuff everywhere! You can't aim the gun real close or you'll get too much in one place. It can also be thinned if you want less texture.

 

[JOeyKnapp]

I will have almost no rust in any of the areas I am working in. I am cutting out anything bad I find and replacing it. Surface rust I am sanding.

I replace the metal at the bottom of the A pillars and would like to do something in that area to protect it. I am almost out of POR-15 (used it on the metal around the engine compartment.

What would be best to treat and/or protect it with?

I plan on using an epoxy primer as my base/sealer..

 

[Gerard]

I think either product is fine. Both need to be sanded or scuffed well before spraying epoxy primer and neither will make a difference if you have any moisture ingress through or under the paint. The Rust Bullet, being harder, is more difficult to get prepped for a good bite for the paint, but I have used both under painted areas. Both have good adhesion on well prepared surfaces. I think Zero Rust is better for large areas you want to spray, the Rust Bullet for spot applications or if you have the patience to apply it with a foam brush. The process is more of smearing it on the keep the thickness down, rather than actually brushing it in the conventions sense. A foam roller can be used as well, but again, keep the application thin. Two think coats are better than one. Drying time is several hours to cure. My tendency would be to use Rust Bullet on areas like the lower A-post.

I can't see any harm in using both in situations where you will be doing body work, i.e. filler; Rust Bullet first and Zero Rust for when you end up sanding through to bare metal. The Zero Rust dries faster and smoother and will be better for build up/touch ups.

On my Morris, I did the entire chassis with Rust Bullet Silver, then scuffed and top coated with chassis black.

 

[apbos]

Thanks for the report. I was wondering if the stuff could be rolled on? I know some bed liners can be. This would make it a lot cleaner to apply.

 

[Guest]

Bed liner under the car, now there is a great idea!

 

[Gerard]

Thanks for the report. I was wondering if the stuff could be rolled on? I know some bed liners can be. This would make it a lot cleaner to apply.

Paul,

I was referring to the Rust Bullet, but yes, the bed liner can be applied with a roller as well. You may not get as good of coverage and you'll probably want to pour it out in small quantities once you've added the activator. The working time in a spray situation I think is like 30-40 minutes, but exposed to air probably much less. I'd check with your paint supplier or their web site.

Gerard

 

[apbos]

Gerard
I thought the Raptor liner would be ideal to roll on since it comes in tintable 1 liter kits (750 ml base + hardner). I figure 4 liters will do the area I want to cover. What amount did you use? Pot life for a liter bottle rolling out should not be a problem I figure. I should be doing this in the next few weeks, so I will post pics while I do it.

Thanks

Paul

 

[JOeyKnapp]

Gerard, is "Blackshell" what you are referring to that you topcoated the Rust Bullet Silver with?

If I have clean metal do I need to worry with any prep other than good primer?

Also, it seems that your PM box is full. Is pixelsmith@gerardsgarage.com still a good contact email address for you? I need to find out about your Master Cylinder rebuild/resleeving.

thanks.

 

[Timmy1959]

I like the Raptor from u-pol. I've used their products before and they work great. I'm wondering if it's transparent and the paint I add will get it red enough. I went to the U-pol site and they say you can add up to 10% of your paint to tint it. If it's black and you add only 10% percent, I'd expect a dirty red at best. Also here in southern California we're restricted to waterborne base coats. I wonder if that type of paint is will mix with the Raptor product. I doubt it. Any one know?

 

[Timmy1959]

On the same topic, has anyone used Raptor liner over the factory tar based undercoat? The factory installed a tar based undercoat and it's still in nice condition on the rear wheel wells. yes, I could spend hours removing it but if it is stable enough for the Raptor to go over it, I'd leave it in place. I've removed it from all the other surfaces on the underside. It liquefies to some extent when solvents are applied. I wonder of the solvents in the Raptor would make a cookie dough sandwich?