How "porous" is red primer?

[dibbons]

Sometimes I like the look of RustOleum red primer (usually the rusty metal primer) and don't use a top/color coat. The first time I did this was back in the '70's when I painted an 8 3/4 rear end before swapping it into my '65 Valiant. I also used the same paint for the interior cast surfaces of my bracket race motors. For the five years I kept the car after that, the primed parts held up almost the same as the day they were painted. I am still doing this on certain parts because I prefer the red oxide look or because the parts are hidden from view.

Last night, I was reading an article on the internet that mentioned how primers are porous, and now I wonder exactly what that means and what the long-term effects might be. Maybe this "porosity" was aimed more at normal body undercoatings and not the high pigment content of the RustOleum I use. Comments?

 

[ChrisPerry]

I'm not a body guy , but I'm pretty sure they are talking about a non epoxy type primer. You can still get rust forming unless it is a "sealer" primer.

I know guys that have cars that are just in primer that have been that way for 5+ years with no issues. They all use an epoxy primer.

 

[adriver]

While I've read and heard the same things you have about primers, I've had very good results with the Rusty Metal Primer. I prefer it to "coatings".
I've been doing this long enough to say my results are time tested.
I overcoat it with other primer before topcoating because of the fish oil base.
I just sprayed it inside some rocker panels to preserve them.
Other than Dinotrol, it's the best thing I know of.
I wouldn't worry about top coating it,
Read the Amazon reviews.

 

[buckshotbishop]

non activated primers are very porous. Generally the ingredient that gives primer body is talc which absorbs water easily. I have found that even activated primers dont prevent rust if they have been scratched.

I guess if your red primer went on thick enough it could help prevent rust, but its also likely hiding it.

 

[barbee6043]

I was looking up primers under TCP GLOBAL on the puter, I use their stuff mainly because I have problems with paints even with good respirator ( I know I need a fresh air suit), and I can get some low VOC from them. I ud=se thei primers, urethane paints, papers etc..... yes they are and ship SLOW!!!!!

they do offer a red oxide color in their epoxy DTM. I have gotten great results with their DTM primer over bare metal, the stuff like ugly on an ape to any GOOD surface. with activator $140/ gal or so., more or less. add reducer for it to be used a sealer, which I do.

like mentioned the old red oxide laquer primers are totally old school and not in the league of modern materials, I think. you can get this primer in red oxoide, grey, black, white. I admit i'm no expert, but have messed with auto primers and paints since the 60's BUT i'm NO bodyman!!!!!
hhhha

i'm sure like anything the more $$ ya pay for any paint materials the better quality, and life it offers. but I don't build mega show cars just try ot have NBO rust, decently straight DRIVERS! if the chemical didn't bother me,, a nd the cost bust my budget, I personally would use PPG products. I have had good results with DuPont, but I have nothing to complain about TCP products.....

 

[ir3333]

regular primer over bare metal will rust if exposed to moisture.
if you want it for cosmetics paint with regular paint as you normally would..
sand w/400 and top coat with primer as your "finish"
.. or primer and clear coat "satin"