[78w72]

Originally Posted by tstroud

I’ve had both results with POR15 manifold paint.
Twice I did a set of SBC rams horn manifolds. They were sandblasted, handled with rubber gloves, washed with lacquer thinner and painted with a brush. Then left to dry for a couple days. Both times they flaked off and rusted in less than a year.
I also did a set of RARE ram air manifolds with the same procedure except I baked them in an old electric oven. They are holding up great so far 4 years later. They only have about 1000 miles on them now so time will tell.

POR and most other high temp paints require a baking procedure to cure properly... cant just let them dry for a few days then expose to full temps. Probably why the SBC manifolds didnt work out compared to the RARE manifolds.

[Formulajones]

Yeah I'm not sure how you guys are having poor results with POR15 manifold paints or what went wrong but I've used that stuff for decades and just as B-man reports the results have been excellent.

In fact I have that stuff on the RA manifolds on my 70 bird that I daily drive. I don't know how many years it's been now but it's been a bunch with I'm sure thousands and thousands of heat cycles and they still look like the day I installed them.

All I did was glass bead them in the cabinet, blew them off with compressed air and applied POR-15 with a brush. Installed them on the car and run it. In fact that's all I've ever done when using this stuff and never had a bad result.

I also have access to ceramic powder coating and a giant oven that I'm doing on headers which works fantastic and I have a wide variety of colors to choose from. Could technically use it on manifolds as well but the POR15 is so easy to do I haven't found a need. The rough texture of the manifolds allows me to get away with just brushing the stuff on, where the headers really need a nice finish, so they get blasted and sprayed.

[gtospieg]

My manifolds were brand new and prepped the way POR said to do it, including baking them in the oven. I'm pretty sure the silver stuff was called POR 20. This was in 2013.

[Formulajones]

Originally Posted by gtospieg

My manifolds were brand new and prepped the way POR said to do it, including baking them in the oven. I'm pretty sure the silver stuff was called POR 20. This was in 2013.

Yeah that's just really strange and honestly unheard of around the car circles I'm involved with. Maybe a bad batch of POR, or maybe prep issues?

I've never done anything special to the manifolds when I use it. Just glass bead, brush on, install on car, that's it. Even on old used manifolds the stuff has held up perfectly.

[78w72]

Ive used the POR20 slver header paint too, used a brush and it lays out to look like it was sprayed. did some lower temp heat cycles to cure as per instructions. It looked awesome & held up for about 7-8 years but the car is stored outside in a dry lean-to shed off the back of my garage for winters so its exposed to lots of condensation as the temps get warmer in the spring, the engine & all metal parts will look like a ice cold soda or beer bottle in humid summer temps, so im sure that shortened its life quite a bit. heres a pic of what it looked like a few years after use.

I also mixed some POR manifold grey with the POR20 silver about 50/50 to make a silverish/grey color and used on the up/down pipes on my turbo 301, that looks like the day it was applied 10+ years ago with no signs of failure.

[tjs72lemans]

I don't remember the POR 15 instructions saying anything about baking. I just bead blasted, cleaned with lacquer thinner and painted. Just as others have done with great results. My poor experience with VHT paints forced me to try this.

[78w72]

Originally Posted by tjs72lemans

I don't remember the POR 15 instructions saying anything about baking. I just bead blasted, cleaned with lacquer thinner and painted. Just as others have done with great results. My poor experience with VHT paints forced me to try this.

Read all safety warnings and precautions on label before use.

APPLICATION:
Liquid paint directions:

On previously painted surfaces blistered and loose paint must be removed. Sandblasting is the optimum surface preparation. Clean painted and bare metal surfaces with POR-15 Cleaner Degreaser to ensure that the surface is clean, dry, and free from oil, grease, dirt, salts, and any other contaminants. Paint all bare areas with two coats of POR-15 High Temp Coating. Glossy surfaces should be roughened with 320 grit sand paper before recoating. Allow POR-15 High Temp Coating to cure for 24 hours on the surface before temperature is raised above 300°F for full cure.

Dry time: Cures to touch in 4 hours. Second coat can be applied in 24 hours, depending on ambient temperature and humidity. POR-15 High Temp reaches maximum hardness after heat exposure above 300°F (150°C) for 15 minutes and then allowed to cool down.

Clean up: Do not put left-over paint back into can. Clean all equipment immediately after use. At the same time, flush out all fluid lines and carefully clean pressure pots. Use clean POR-15 Solvent only. It is also good practice to periodically clean the spray tip or the fluid tip/air cap combination during the course of the working day or shift.

Aerosol spray directions:

Surface must be clean, dry an free of all oil and other contaminants before painting. Sandblasting is the optimum surface preparation. Protect surrounding areas from spray mist. Must be heat cured at a minimum temperature of 400°F (205°C) for two hours. More than one coat may be required for full hide.

Shake can at least one minute before and occasionally during use.
Spray surface with steady, even strokes at a distance of 8 to 10 inches. Several light coats give a better finish than one heavy coat. For best results, recoat within 1 hour or after 24.
Cleanup: To prevent clogs in spray nozzle, hold can upside down and spray until clear gas appears. Completely empty cans may be recycled or disposed of with regular trash. Dispose of partially empty cans responsibly. DO NOT puncture, incinerate or compact.


https://por15.com/products/high-temp

[Formulajones]

Are you guys spraying it? Maybe taking the pint can and thinning it down to spray?

Im just trying to find the difference.

I don't do that, I use it straight out of the pint can with a throw away brush. I was never remotely interested in running that stuff through my $800 gun.

[tjs72lemans]

Brush on, not spray. I guess since I wasn't using aerosol, that's why my can never mentioned baking it on. It doesn't require that.

[78w72]

Originally Posted by tjs72lemans

Brush on, not spray. I guess since I wasn't using aerosol, that's why my can never mentioned baking it on. It doesn't require that.

I posted the instructions for both brush on & spray aerosol... both say that a curing process is recommended for maximum hardness. The brush on does require that for best results.