So I have a buddy, he's a painter, and a pretty good one.. He heard from a couple guys in the industry that REALLY REALLY talk down about leaving a car, or any part for that matter in bare metal for any time at all. Not even running the car bare, but building it and keeping it bare while under construction. He says it causes adhesion problems with the paint or something?? Can anyone elaborate on this for me? I figure with so many immensely talented builders, who clearly know what they are doing, building cars that stay bare metal all the way until the end, that it can't be THAT big of a deal?? This guy is talking like it's a serious sin, and I'd like more of a perspective.. Thanks fellas!
I'm no expert but I don't think the metal cares how long it's been bare as long as it's prepped before paint. Look at all these rusty cars that have been that way for years and then prepped and painted.
its better to let the metal sit bare than let it sit in primer for too long. Primer CAN absorb moisture and result in paint failure down the track. At least if the metal is bare you can see whats happening to it. I have kept my 57 Chev in bare metal for quite a few years (too many!! ) and just wipe it over with a rust inhibitor from time to time. I'll just run over it with a DA sander or such...prime it..and paint it. Ultimately only paint will seal and protect the surface ,but leaving it in bare metal is no problem and I been doin this for 20+ years. thats my .02 PB
Why do you want it in bare metal just to have to DA it again to put down a wash primer and epoxy sealer such as DP 40? I would do what you have to do when you are ready to do body and paint then do it. My 2 cents, did it 25 years!
I would suggest wiping it down with an acid metal cleaner and then spraying it with a good epoxy primer. Any epoxy or uerathane primer won't absorb moisture but laquer primer will
Hey, Steel + oxygen + water = iron oxide ( rust)! Rust, or iron oxide is not a very good foundation to build a good paint job, to say nothing 'bout a plastic filler repair upon. If the fine grains of the surface of the steel contain iron oxide, and are not treated/removed, and they come in contact with moisture via from thru the top coat or from behind the repair/paint job, you have more iron oxide.
Phosphoric acid/ferrous metal conditioner. http://www.42gpw.com/acid.html After the metal is treated or phosphated, clean it and it's ready for primer (but not etching primer).
I use Genolite phosphoric acid to keep surface rust at bay for a while.works great. just Festo it back and your good to go
I've painted cars for almost 50 years. Metal don't care and paint don't care. When you're ready for paint,clean and prep the metal properly as for any job. As long as there are no contaminants on the metal, the paint will stick. If not prepared properly, it will not stick well...
Hmm.. I'm just getting sick of hearing him bitch about the bare metal spots on this motorcycle I'm working on.. The way I figure it, before this sheet metal looked like a sportster tank, or a quarter panel or whatever, it looked like a big big piece of bare metal.. Right??
Steel begins to oxidize immediately so he is somewhat right but only if you were to leave the metal bare for a long time and then painted over it without doing any sanding to clean the steel. Many builders will have the car in bare metal through the build because there is a lot of welding going on through the build and in terms of welding you need clean bare steel in order to get a perfect weld but when it is time for paint the whole body of the car will be sanded again just before paint, leaving steel bare for extended times will affect the adhesion but that is why a car SHOULD be prepped just before paint but your buddy shouldn't be giving you grief just for having some bare steel exposed while you are working on it.
Even a painted surface that is sanded and allowed to sit will start oxidizing in a few hours. It's not even good to sand a painted item and leave it for day,weeks,or months without re prepping it. All surfaces oxidize over time. Some quicker than others...
What part of the country you're painting in obviously dictates how much humidity you have to deal with on a normal basis. I've painted in Fort Worth where Ditzler is formulated for high humidity in mind, and in drier parts of the country. The hidden cracks and crevasses are what 'gets you;' after blasting or 'dipping' you'd normally want to add some relative protection to bare metal but, as has been implied here already, priming does attract moisture and can be worse than leaving the metal bare. My rule of thumb, if my job is going to be sitting for any length of time, is to prep it immediately after blasting and lay on Lac Primer thinned 200%; it tightens up and acts as a great sealer. Every painter finds what works for him or her, and always tries something different down the line. This works for me after 1000 plus high end paint jobs, . . . .that is, until I try something different!
I don't see a problem if you don't rub your hands all over it all the time. Lynn wouldn't even let me in the shop if he had one bare, I'm a mechanic and that is not a good thing to be around a car that wants to be painted. We even had separate tool boxes, mine was the one for mechanical work and his for anything to do with body work.
x2! Where I live in there very high humidity the metal will flash rust in minutes..somtimes you can't see the rust with your naked eye..but it's there!
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