Por15 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Paul Clark · 05-24-2002, 10:49 AM

Can you put Por15 over undercoating?
Want to do the bottom of the cab, but there is undercoating in some spots that I can't remove.
Por15 over everything?
Just on the bare spots?
Don't use it. Just get some more undercoating?
Thanks

johnnyp · 05-24-2002, 11:26 AM

Some will say that you don't know what's going on beneath the undercoating, but IMO if it's still stuck on good and there is no visible signs of rust on the inside floor of the cap, then it's probably OK. Putting POR15 over the undercoating probably won't help, but it won't hurt anything either, so I say, clean it as best you can and slap POR 15 over all of it. Of coarse, I don't have a clue how POR15 will affect the undercoating, but I don't think you'll hurt anything by experimenting.

------------------
72 Sierra Grande - "Maych"

If a man speaks in the middle of a forest and there is no woman around to hear him, is he still wrong?

Forget about "do it right the first time". Do it wrong the first time to learn how, then do it right the second time.

bigvinnie · 05-24-2002, 11:28 AM

I figure if it says you can paint over rust then you can paint over undercoating...

72chevyLWB · 05-24-2002, 03:08 PM

POR 15 is not as good as people say it is. Maybe I just screwed up. They say paint right over the rust just get it clean. Well I pressure washed the frame, then used their marine clean cleaner, then painted. Well, if you scrape the paint it will come off. and if it gets chipped bad enough it will peel right off. I would atleast sand everything with 180 grit before you paint it or else it won't be as strong.

------------------
72 Chevy C/10
87 Chevy Silverado 4X4
www.geocities.com/chevylwb/chevylwb.html
Aberdeen South Dakota
WANTED: Drop Spindles
F/S: rebuilt Turbo 400 & Aluminum wheels w/ tires

shadetree · 07-07-2002, 01:55 AM

I am having a lot of trouble with POR-15. After following the instructions, 100%, this stuff is flaking off, peeling, is sensitive to acids, it is NOT flexible, it is NOT anything else POR-15 claims it to be! I also tried POR-15's exhaust treatment, it comes off, after several months use. I cannot get POR-15 to answer my E-mails, either. I'm pissed!

mikep · 07-07-2002, 03:25 AM

Ive posted it on here before. The guy who owns the NAPA store in Poulsbo Washington also owns the POR-15 company. All of it. He's in the store most days of the week as he also manages it. Give him a call. I'm sure he'd love the feedback.

To be honest I used to use the stuff all the time to paint guns with back when I ran a gunsmithing outfit. Went through a gallon or more of POR-15 a month easy. I used the chassis black and painted assault rifles that had been properly prepped as in rough sandblasted with ground glass, thouroughly washed and acid etched with a phosphoric acid solution, baked to 400F then painted 3 coats and baked at 400F for an hour or two. The stuff would NEVER come off after that and it looked great and was way tougher than any commercially available gun paint. Gun barrels get a LOT hotter than exhaust manifolds. Its the way I do pulleys, accesories and headers for cars now. I even have an oven in my garage. Painting over rust is just stupid no matter what the label says. Its cyanoacrylic paint . Its not magic.

05-24-2002, 10:49 AM	#1
Paul Clark Registered User Join Date: Apr 2002 Location: Center Point, IA Posts: 502	Por15 Can you put Por15 over undercoating? Want to do the bottom of the cab, but there is undercoating in some spots that I can't remove. Por15 over everything? Just on the bare spots? Don't use it. Just get some more undercoating? Thanks

05-24-2002, 11:26 AM	#2
johnnyp Keepin' It Stock Join Date: Aug 2001 Location: Grand Island, Nebraska, USA Posts: 554	Some will say that you don't know what's going on beneath the undercoating, but IMO if it's still stuck on good and there is no visible signs of rust on the inside floor of the cap, then it's probably OK. Putting POR15 over the undercoating probably won't help, but it won't hurt anything either, so I say, clean it as best you can and slap POR 15 over all of it. Of coarse, I don't have a clue how POR15 will affect the undercoating, but I don't think you'll hurt anything by experimenting. ------------------ 72 Sierra Grande - "Maych" If a man speaks in the middle of a forest and there is no woman around to hear him, is he still wrong? Forget about "do it right the first time". Do it wrong the first time to learn how, then do it right the second time. __________________ 72 Sierra Grande - Maych Forget about "do it right the first time". Do it wrong the first time to learn how, then do it right the second time.

05-24-2002, 11:28 AM	#3
bigvinnie Registered User Join Date: Aug 2001 Location: escondido, ca 92026 Posts: 1,222	I figure if it says you can paint over rust then you can paint over undercoating... __________________ '72 short step, 350, 700R4, tilt, ps, pdb, a/c, lowered coils, etc., other work in progress... San Diego, CA 72 Stepside Project

05-24-2002, 03:08 PM	#4
72chevyLWB Got 20's???? Join Date: Oct 2001 Location: Aberdeen SD Posts: 1,451	POR 15 is not as good as people say it is. Maybe I just screwed up. They say paint right over the rust just get it clean. Well I pressure washed the frame, then used their marine clean cleaner, then painted. Well, if you scrape the paint it will come off. and if it gets chipped bad enough it will peel right off. I would atleast sand everything with 180 grit before you paint it or else it won't be as strong. ------------------ 72 Chevy C/10 87 Chevy Silverado 4X4 www.geocities.com/chevylwb/chevylwb.html Aberdeen South Dakota WANTED: Drop Spindles F/S: rebuilt Turbo 400 & Aluminum wheels w/ tires __________________ 99 Silverado Ex-Cab 2wd, Bagged&WhippleCharged 02 Sierra Ex-Cab 4wd 2500 HD The 72 went down the road.

07-07-2002, 01:55 AM	#5
shadetree Senior Member Join Date: Dec 1999 Location: Knightstown, in, usa Posts: 2,525	back to top I am having a lot of trouble with POR-15. After following the instructions, 100%, this stuff is flaking off, peeling, is sensitive to acids, it is NOT flexible, it is NOT anything else POR-15 claims it to be! I also tried POR-15's exhaust treatment, it comes off, after several months use. I cannot get POR-15 to answer my E-mails, either. I'm pissed! __________________ 1970 long fleet, 355 4 speed, primer, walnut goodies

07-07-2002, 03:25 AM	#6
mikep Used to have a truck Join Date: May 2002 Location: port orchard WA Posts: 1,552	Ive posted it on here before. The guy who owns the NAPA store in Poulsbo Washington also owns the POR-15 company. All of it. He's in the store most days of the week as he also manages it. Give him a call. I'm sure he'd love the feedback. To be honest I used to use the stuff all the time to paint guns with back when I ran a gunsmithing outfit. Went through a gallon or more of POR-15 a month easy. I used the chassis black and painted assault rifles that had been properly prepped as in rough sandblasted with ground glass, thouroughly washed and acid etched with a phosphoric acid solution, baked to 400F then painted 3 coats and baked at 400F for an hour or two. The stuff would NEVER come off after that and it looked great and was way tougher than any commercially available gun paint. Gun barrels get a LOT hotter than exhaust manifolds. Its the way I do pulleys, accesories and headers for cars now. I even have an oven in my garage. Painting over rust is just stupid no matter what the label says. Its cyanoacrylic paint . Its not magic. __________________ No truck :-(



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