Auto spray paint failure?

[JHZR2]

I replaced a hinge on my 96 Ram, and had painted it to match.

I fully degreased, used HF (USA made) self etching primer, Then single stage automotive paint in a match color. I just looked at the hinge today has been opened maybe 10 times and there was nothing that ever rubbed on it and I see this:

It has been fairly dry since I did it, and the hinge had a few days of cure time before the install.

Is it because I tried to paint galvanized?

 

[Rand]

before I read your last line.. I was already thinking galvanized issue.

From the title I thought maybe this would be talking about the model Y terrible paint issues.

 

[Warstud]

I fully degreased, used HF (USA made) self etching primer,

Looks like an adhesion problem for sure. Bad primer. What is HF primer ?

 

[97prizm]

I would have tried a zinc self etching primer used for aircraft.

 

[JohnnyG]

Yeah, you can't paint galvanized metal without a self etching primer. It just won't stick. scrape the paint off and it will look just fine.

 

[Gimpy1]

Looks like an adhesion problem for sure. Bad primer. What is HF primer ?

Yea it looks like paint incompatability. Car refinishing is a system designed to work together. The best thing to do is use primer and paint from the same company and same model numer. 3M makes a good sytem or you can go to Www.touchupdirect.com and get a complete kit with your car color.

 

[Silverado12]

Way back when I was in school in the service we used zinc chromate primer. It looks yellow/greenish. That's been 40 years ago, so maybe they have something more modern now.

 

[JC1]

If that was my vehicle, I would have those parts of the door fluid filmed, so I wouldn't worry about it. I would scrape off the loose paint first and reapply FF or whatever rust proofing you choose.

 

[JHZR2]

Looks like an adhesion problem for sure. Bad primer. What is HF primer ?

Yeah, you can't paint galvanized metal without a self etching primer. It just won't stick. scrape the paint off and it will look just fine.

HF Self etching primer is just that - self etching primer sold by Harbor Freight.

It is made in USA, and HF doesn’t make their own chemicals, so I figured it was relabeled rust oleum or krylon or duplicolor.

 

[JHZR2]

If that was my vehicle, I would have those parts of the door fluid filmed, so I wouldn't worry about it. I would scrape off the loose paint first and reapply FF or whatever rust proofing you choose.

That is in the cards. FF lasts pretty well in no wash exterior areas like door jambs IME.

 

[JohnnyG]

HF Self etching primer is just that - self etching primer sold by Harbor Freight.

It was obviously an inferior product, or at least not designed for galvanized metal. Since these parts are galvanized, why are you worried about them rusting? Keep a light coat of oil on them whenever you lubbricate the hinges and they should be fine.

 

[doitmyself]

I'm no expert on this topic, but do know that alkyd paint will have a negative reaction on galvanized (saponification) after a period of time.

I've read that it is best to use water based mild acid wash as the final rinse vs. a solvent rinse. Maybe the primer was incompatible for adhesion. Maybe there was an interaction between the primer and top coat. That's all I can think of.

 

[JHZR2]

It was obviously an inferior product, or at least not designed for galvanized metal. Since these parts are galvanized, why are you worried about them rusting? Keep a light coat of oil on them whenever you lubbricate the hinges and they should be fine.

I was more interested in roughly matching the paint color like OE.

I didn’t find much info at all on the HF paint. Rust oleum has a use guide and says to not use it on galvsnized.

Im surprised and a little annoyed.

A few years back, I built a playground for my kids, including a ladder and fire pole. I used all galvanized electrical conduit, and we painted it all red. The ladder I even used some grit to get a better grip.

On the conduit all I did was wipe with ospho, then paint with Case Tractor Red Ace Rust Stop paint. It still looks and adheres well hears of use later.

I guess the secret is ospho vs self etching primer?