DIY Painting Tips

[stopintime]

DP: thoughts about a steel SportClassic swingarm painted or powdercoated clear?

Probably a flat clear because the point is to leave it as 'steel' as possible.
Suggestions on how to prep it for an old 'non-pretty' look?
Polish and then sand a little? Leave it in the rain? Sprinkle with salt water?

(not mine)

[ducpainter]

I think I know the effect you're looking for. Not really sure the best way to achieve it. It isn't what I do.

The problem is neither process will stick to rust long term.

That said...

I'd avoid salt.

One method would be to spray it with phosphoric acid, rinse with water, and let it flash rust. Don't handle with bare hands afterwards.

Another method would be to sand it and then handle it and let it sit until the skin oils start the rusting. Then wash with solvent to remove the oils.

Since neither process, powder or paint, will last in the really long term so I'd go with whatever is cheaper.

[Langanobob]

Finally something I know something about; rusty steel.  Here is what I'd try, but first test in on a piece of clean scrap steel to see if it's anything close to what you're looking for.  Clean the swingarm with a hot water detergent solution to remove all oil residue that might be on it.  Then spray it down with water and leave it somewhere it will rust.  After it's got a coating of surface rust, soak it overnight in a plastic tub or something similar full of a dilute solution of phosphoric acid.  The stuff is sold here as a metal prep for painting and I usually dilute it about 50% or more with water when I'm soaking a rusty part.

Pull it out of your cauldron and dry it with a rag.  It "should" now have sort of a grey gun metal patina that may or may not be what you're looking for.

You mentioned it isn't your bike and my opinion on this kind of finish is that a good bike is an elemental machine in its own right and doesn't need any artificial elementalness in the form of fake patinas.  But, to each their own.

[stopintime]

Thanks guys,

gun metal patina sounds about right (in my mind) - I'll discuss it with the owner.

Thoughts about clear paint/powder adhesion on that type of finish?
Leave it without paint?
Anodize?

[ducpainter]

You can't anodize steel.

Either process works well with a phosphate coating.

In the automotive trade we always neutralize the acid with water, but that can cause flash rusting.

[Langanobob]

Nate,

I have a question about respirators.  What do you use?  A positive air system?  I'm normally not much of a handwringer when it comes to health and safety issues, but since I don't understand lungs, I worry about them.

Thanks,

Bob

[ducpainter]

Nate,

I have a question about respirators.  What do you use?  A positive air system?  I'm normally not much of a handwringer when it comes to health and safety issues, but since I don't understand lungs, I worry about them.

Thanks,

Bob

Bob,

The safety experts will disagree...

but it really depends on ventilation IMO.

I use 3M part # 7192, and have for a lot of years in booths with good ventilation.

Nate

[Langanobob]

Thanks.  The effect of good ventilation is something I never considered, not having a spray booth.

[stopintime]

Is it possible, with a good result, to paint on top of powder?

[ducpainter]

You'll need to abrade/sand every square millimeter.

Powder has no 'pores' like liquid paint does when it dries. If you can't sand everywhere I wouldn't paint over it. Adhesion promoters won't help for the same reason.

[stopintime]

You'll need to abrade/sand every square millimeter.

Powder has no 'pores' like liquid paint does when it dries. If you can't sand everywhere I wouldn't paint over it. Adhesion promoters won't help for the same reason.

Ok - will do it properly or not at all 

[Dirty Duc]

I just used to coat some copper I didn't want to tarnish.  They have a satin that apparently will seal in the patina...  I have no information on longevity, but it went on pretty easily.

[MonsterMadMarty]

Hi DP,

I spray painted my 95 M900 engine the other day using VHT Engine enamel I then left it to bake in the sun (two days of 30 degrees C or about 90 in F).  Once it was back in the garage and under very close inspection i've notice an area where the paint is a little thinner than other areas.  If I wish to give another coat after three days of drying should I give it a little sand first or will just a quick rub over with pre-paint prep be ok?

Secondly, should I clear coat or will that make it look too glossy? (I'm trying to get a factory look finish).

Cheers,

Marty

[ducpainter]

I'd follow the manufacturers recommendation for re-coating. Re-coating spray can enamels can be tricky before a one week dry, and sometimes longer depending on drying conditions. If the manufacturer says a week, they mean a week at 70 F and 50% RH. What happens is the solvents in the subsequent coats attack the semi dry material on the surface and cause it to wrinkle and lift. Trust me...you don't want that to happen.

If you are the impatient type use very light coats and let them partially dry. You don't want an abundance of fresh product on top of the already applied paint. Be prepared to say....Faaaaack.

I also don't recommend clearing that product as it will get pretty glossy.

[MonsterMadMarty]

I'd follow the manufacturers recommendation for re-coating. Re-coating spray can enamels can be tricky before a one week dry, and sometimes longer depending on drying conditions. If the manufacturer says a week, they mean a week at 70 F and 50% RH. What happens is the solvents in the subsequent coats attack the semi dry material on the surface and cause it to wrinkle and lift. Trust me...you don't want that to happen.

If you are the impatient type use very light coats and let them partially dry. You don't want an abundance of fresh product on top of the already applied paint. Be prepared to say....Faaaaack.

I also don't recommend clearing that product as it will get pretty glossy.

Cheers, I'll leave it two weeks then. I still have to reassemble the heads and that may take awhile.