I see trucks and cars all the time (my old F100 included) driving around with varying shades of primer coats. Does a primer coat protect against rust? I was wondering if I could attack some rusty parts of the sheet metal in stages and yet still be able to use the truck.

Thanks.

 

NO by it self primer will not protect in fact it can speed up rust as it is porous. Most "hot rod" painter that wish to leave the primer look add 50% top coat paint to primer or just use flat paint.

If you want to patch up your truck use primer then top coat it with a rattle can paint it will keep the repair good. if you need to work more on the same spot scuff off the top coat.

Remember proper ventilation and where a respirator!

44Dwarf

 

there are some primers that are a epoxy sealer that do block out moisture. the used a sherwin williams epoxy sealer on mine to get me through the winter that is designed for just that

 

Not really designed for it but it will work the main reason for epoxy primer / sealers is to seal in any spots where to much hardener was mixed in with the bondo thus it can lead to bleaching of the top coat and many of the new paints are not compatible with the older paints they'll wrinkle so you have to used a sealer keep the two layer apart but the top layer is still porous to allow for adhesion.

44

 

I don't like to disagree with 44dwarf, but I must about the reason for Epoxy primer/ Sealer. It was originally developed for use over fiberglass, but has been adopted for use over bare metals, and with good reason too. I have a grip on refinishing!

It's main reason for existance is to provide a stable and impervious substrate covering on which a finish can be built. It is truly a sealer. the difference being there are primer surfacers then there are primer sealers. They serve 2 distinct functions. He's correct about "blocking" over filler coats such as the polyesters, like Bondo or Tigerhair etc. It also seals or barrier coats bleedable finishes, such as reds and oranges etc.

Primer surfacers are virtually porous and designed to provide an adhereable substrate for finish coats to "stick" to., But their porousity makes them "non-sealing". In fact primer surfacers because ot their microscopic structure, act like a spongs and not only allow moisture (aka water, salt, dew, roadwash, etc) to reach the metal below, they actually retain moisture increasing the probability of corrosive action. Epoxy Primer/ Sealer stops that from happening. Tints can be added to Epox' P/S to create what has lately become known as "Suede Paint Jobs" [a colloquialism for primer surfaces used as a finish coat] popular during 40's/ 50' and recurring now in some of the finer "Rat Rods" of today. Technology has brought us the Epox' P/S chemistry of today, as well as the multi stage BC/CC or BC/IC/CC Polyurethane Straight, Metallic, Flipflop, & Pearl finishes used today. In closing, there is another multifold factor about the Epox' P/S.

Not only is it primer/sealer, it is (IMHO) the best way to apply fillers from polyesters I mentioned above, to high build primer surfacers, feather fill and so forth. . . . All of these are best applied over the Epoxy Primer Sealer. Again IMO they bond better to the Epox P/S than they bond to bare metal or fiberglass (which is what Epoxy P/S was actually originally formulated for.

So with Epox' P/S one can repair one spot or one panel or one side at a time over a several year period without fear of rust starting and coming through as it does with all non sealing primers.

The epox's will sustain up to 5 years or so in the elements when properly applied. Their worst enemy is Uv A & B which attacks their "benzine ring structure" over time. It should be pointed out that most paint jobs are past their peak in 5 years anyway.

Last point. Epoxy primer sealers are really tough to sand out after a long cure period, so there is a "window" of opportunity after which they require a "Dusting" before more other finishes should be applied, in order to preserve best adhesion to them. I suggest any imperfection be worked within 24-48 hour window & area be blocked before long term curing happens. That way, up to a few years, a freshening coat can be "dusted"
over it and the final color coats(s) applied.

FBp

 

FBp, You are "The Man"!

 

Thanx for the flowers William! I appreciate the good words.
Some of my finishes have appeared in ISCA and other National Auto Shows over the years. I do not do any "outside" painting for others anymore. Although I have been known to "squirt" a few of my own vehicles now & then.
FBp

 

fBp... Quick question about painting fiberglass. You mentioned painting fiberglass with the Epoxy Primer, I was planning to paint epoxy primer on my 1980 flairside rear fenders and fiberglass Morris Minor bumpers this week. My flairside fenders have always had small cracks in the paint, I guess from flexing and all the dirt roads it's traveled. Is there a flexible coating I can spray on between primer and paint to prevent the cracking?? What do they do for high end fiberglass cars ie: vettes etc.
Thanks Pete.

 

Was going to suggest going to 'paint and body forum' but FBp explained about as best as anyone can. First time painter and had heck of a time getting a finish on truck w/out getting blisters, bubbles, what have you, surfacing within short period of time. Same results on second attempt then decided to re-sand and use epoxy p/s. This was about 6months ago, so far paint job looks good.

dave

 

M M,
I'd suggest using Epox' P/S as your substrate on the prepped "FG", then add flex agent to your final color coat. It's how they get away with polyurethane bumper covers & other "rubbermaid" like trim parts they're using these days.

However, stay with a single stage color/finish coat as IMHO, flex agent does not work with BC/CC and/or other multiple stage finishes. A quality acrylic or synthetic finish should work fine. You should get 6-8 years out of it.

Flex Agent is available at any good Auto Body Paint & Supply Jobber, make sure what they give you is compatible with which ever finish you decide to use. . . . Follow the label instructions.

Vettes are shot with BC/CC and they do crack over time. Even Gel Coats used in FG Street Rod Bod's & Marine apps crack eventually. Ever see older Imron Finish? Had a 55 Blow Tie to re-do a while back that was shot with Imron when it 1st came out. It looked like Gator Hide and would not come off or sand out either. I've never seen a finish so hard. It was like trying to work with window glass! Last one I'll ever do!

FBp

 

Thanks pete, that's just what I needed.

 

Wow Pete you should be an instructor. My son is in a street rod building training class and some of the instructor's words have caused me problems because they didn't follow "real life" experiences. I'm a guy who started as an apprentice with hot enamels, no-clear lacquers and lead. I remember a Dupont salesman coming into the shop with a paint that would "change auto body refinishing forever" Centari he called it. LOL

 

Glad to be of assistance. . . .
I was a college instructor after I was an Adult Ed Vocational Habilitation Specialist. I also taught EMR and TMR mentally challenged people skills they could use to get jobs instead of collecting on the "dole" In fact I got 12 of my 36 students paying jobs in the 2 years I taught the retarded folks.

It was a really great rewarding experience. I could not believe how much it meant to them to be able to be self supporting, independent and to live in a group home with others like themselves. They actually became people with pride & purpose. They still thank me if they see me around and it's been 15 years now.

I guess y'all figured out I'm not really a Boy, but I am! I'm 19 years old, I just have 46 years experience at it. . . . Heh heh heh. . . .

FBp