Painting

[jmh21586]

I like to refurbish things, sand them down and repaint.

My only option right now is rattle cans. No matter what I do I can't get a paint job to adhere one bit. I take off old paint. Clean with denatured alcohol, prime and paint and still I can scrape it off with a fingernail.

What am I doing wrong?? Is it the fact that I'm using spray paint??

Am I not priming correctly?? What primer should I use on bare metal?

 

[GregN]

When you apply your paint, do you put one cover coat on, or do you dust the part initially, and then put a few additional light coats on until the entire part is covered? I have always covered in the first coat, and finally tried just putting a really crappy thin coat on first followed by some heavier coats and it has made a world of difference. That first light coat helps to bond the paint to the substrate (or primer in this case).

I thought this was all BS until about a year ago, and am now a firm believer.

 

[jmh21586]

I've tried both ways. Usually do a thin coat first and then a final coat. I still have problems with adhesion. It's like the primer doesn't stick at all.

 

[yiranhu]

Probably the wrong primer for the application. Also I assume you are following the drying time for recoat and the temperature requirements right?

 

[GregN]

How old is the paint? Are you shaking the cans for more than a few seconds before starting? If you don't mix the paint enough it won't seem to dry all that hard. My friends boss made a rattle can paint mixer that attaches to the end of a drill. I will have to take some pictures of it when i get a chance.

 

[gorilla]

Paint will not adhere to iron oxide (bare steel), it needs to be converted to iron phosphate. This is accomplished with a product called metal prep it should be avalable at any automotive paint store. Also be sure that you clean the metal before you sand it if not you may force oils into the metal.

 

[jmh21586]

Also I assume you are following the drying time for recoat and the temperature requirements right?

Yep. Most is quick drying paint.

How old is the paint?

Some old, some brand new.

Are you shaking the cans for more than a few seconds before starting?

I shake them for a few minutes usually.

Paint will not adhere to iron oxide (bare steel), it needs to be converted to iron phosphate. This is accomplished with a product called metal prep it should be avalable at any automotive paint store. Also be sure that you clean the metal before you sand it if not you may force oils into the metal.

Ok. This metal prep.....is that the same thing as an acid etch primer or something along those lines?? What I mainly have been using is automotive primer. As far as cleaning I was using denatured alcohol before priming.

How about the diferent types, such as acrylic, enamel, etc??




I really appreciate the help fellas. I finally got my shop done to where I can do all the projects I've wanted to do for a long time. Just want the final product to turn out as nice as possible.

 

[ZRX61]

Paint will not adhere to iron oxide (bare steel), it needs to be converted to iron phosphate. This is accomplished with a product called metal prep it should be avalable at any automotive paint store.

Iron oxide is rust, not bare steel... & lots of paints will stick to bare steel.

 

[jmh21586]

Do most paints have a curing time beyond the dry to a touch time??

Maybe I'm asking too much of freshly painted things.

 

[jmh21586]

We use some primer at work for priming steel lentals before we brick in openings. This stuff is amazing. Can't hardly wash it off my hands let alone scratch it on the metal.

Does red oxide primer sound right?? I don't know. Maybe I should use that stuff and just brush it on and then spray paint over that. I'm guessing spray paint is probably not the way to go anyway if you want the paint to last.



I also tried using that krylon plastic paint. Says no primer needed. Painted a hopper I'm using for floor sweep. Cleaned it real good. Sprayed it. Next day I could scratch it right off.

 

[silver hair deere]

I like to refurbish things, sand them down and repaint.

My only option right now is rattle cans. No matter what I do I can't get a paint job to adhere one bit. I take off old paint. Clean with denatured alcohol, prime and paint and still I can scrape it off with a fingernail.

What am I doing wrong?? Is it the fact that I'm using spray paint??

Am I not priming correctly?? What primer should I use on bare metal?

i always scuff up the metal with 320 sandpaper then clean with metal prep

SHD

 

[LoneGunman]

Depending on what you are painting you may want to go with a brush. I restore a good amount of machinery if I'm not powder coating the parts, 98% of them are painted with a brush, most of the time I use rustoleum smoke gray, it will usually need to be thinned and don't even think about using a cheap brush, Purdy is the lowest quality I'll use. I have had better results WITHOUT primer on bare steel with the rustoleum, I have Iron Phosphate tanks in house for the powder coating. The paint will be soft for a week or so. The only parts I spray are large flat parts, I'm not good enough to paint them with a brush without getting brush marks. When I spray I use a HVLP touch up gun, an Iwata clone from horrible freight.

I think your problem is your prep work. I don't like denatured alcohol as a cleaner. I preclean with hot water and simple green, then I sandblast the parts. After sandblasting I do NOT touch the parts with my bare hands. I blow the parts off and then depending on the size I'll use a heated tank and let them soak awhile, they I'll scrub them with a nylon brush.

A good way to tell if a part is really clean is to do what's known in the plating industry as a water break test (you can google instructions) basically it just entails pouring water over the part, if the water beads up at all you have oil contaminates, if the water sheets off the part is clean enough for what you want to do.