ok so i am doing my first total bike resto...

I have some really really rusterd pieces (clamps, skewers, etc) that i cleaned by soaking in an acid bath (white vinegar). came out awesome, super stoked. Dried them off and bagged them.

Looked at them 5-6 hours later and a surface layer of rust had re-formed?

So... did i not let them dry long enough before bagging or should i be treating the pieces with something afterward?

Ummmmm I think it may have been operator error, you don't mention rinsing them down if you left the cleaner on and wiped it down I'd think it would leave a surface film of the rust... originally when I read the title I thought maybe you'd cleaned out pitted rust and down the road it rerusted (quite common). My brother in law has a chrome polish it's kind've waxy and you have to recoat it every so often to just like waxing a car, but it protects your parts from rust build up. If you want a quick simple way to remove the surface rust, just grab some windex and aluminum foil, it'll even remove rust from inside pits.

Some steel parts freshly cleaned by chemicals or even sandblasting can flash rust very quickly, just from the humidity in the air. Treat them with the rust preventative of your choice right after they have been cleaned. I use different coatings depending on the final use of the part, anything from light oil, to spray wax, to clear coat paint . . . .

ok just to clarify. they sat in a bath, i rinsed them with running water, patted dry, bagged.

i have since re-removed the surface rust and am trying a more thorough drying process... largely because i dont have any rust preventer on hand. will have to make a trip to the store later...

oh and believe me they needed the bath, this bike had been sitting abandoned outside in the dirt for over 10 years.

Probably like he said then, just a flash surface rust. Time to get some rust preventer

+1. in the right (by which I mean wrong) environment, bare metal can start re-rusting in minutes. At the very least, once they're dry, spray some oil or rub some wax on them. That'll keep them pristine until you're ready for a more thorough coating.

Not that you asked, but one unusual coating that can look sharp is blueing, like they use on guns. The cold process is pretty easy, and if done right the end product looks like liquid night.

You have to put something on them or they will flash rust again.Vegetable oil,butter,bacon fat,WD-40,wax,something.

With your vinegar bath complete and the rust apparently gone, dry the pieces off. Now take one of the pieced and rub it with a crumpled up piece of aluminum foil. Before rubbing, run your hand or fingers over the piece and feel how rough it is. After rubbing, feel again. You will be amazed how much smoother the piece feels.

Now,wax the piece with a decent wax. I use Mothers Cleaning Wax and it works great.

That should take care of the rapid rust return and you will have removed even more of the rust with the rubbing action.

Hope this is a help.

Mother's cleaning wax, got it...

one more question... if i intend to use metal polish on the pieces, would that act as its own sealant/rust prohibitor?

I don't think so but give it a try. Personally, I never bother with metal cleaner. I use soap and water, a soft brass wire brush, a nylon scouring pad and the mentioned wax. And, of course, I swear by the aluminum foil thing. Honestly, try a small spot and you will see/feel the difference in moments.

I concur on the aluminum foil. I was shocked that it works, but it does.

Some polishes will leave a coating, but it's VERY thin. Simichrome polish and the Flitz polish I use in my vibratory tumbler both seem to leave a coating on the parts. If the parts are to remain unpainted just a shot of spray silicone or WD-40 will work for a while.

What exactly are the parts made of, and/or coated with, to begin with? If they are bare steel, they are going to rust no matter what, unless you put some sort of protective coating on them. Paint, chrome, clear coat, etc. If the pieces are what looks like bare steel, chances are they had some sort of clear coating on them to start out that is gone now. If they are chrome plated and were rusty, the rust will keep coming back from the pits in the chrome surface that go down to bare steel. You can slow that down, but it is hard to stop it. Steel and moisture don't go well together, so you need to somehow separate the two.

The parts didn't get as dry as you thought. When bagged, they had a moist environment to flash rust.
I usually air dry with a blow gun/compressor, or spray it with WD40. (Water Displacement formula 40).
Bagging them afterwards usually results in no rusting.
Silicone is a good spray to use to prevent rust later.