anti rust painting

[samsarani]

Dears
please send me some information about following question

how does anti rust paint apply on rusted iron?
is metal cleaned at first or could apply anti rust painting on rusted metal?
please consider i can't see any laminated or pitting area on base metal( we buy new produced metal two week ago and in this duration we had rain for 3 days we see only Orange color in base metal)

thanks all

 

[dik]

There are some coatings meant to be applied over rusted surfaces. My preference is to start with a pristine surface and use a proper coating for the environment.

Best to check with various manufacturers to see what they would recommend for the end use.

Dik

 

[MikeHalloran]

The various waterborne rust conversion coatings sold under the Duro name and others actually work pretty well, with certain conditions:
- You must remove loose rust and scale, e.g. by wirebrushing.
- You must remove any organic contaminants, e.g. by solvent wipe.
- You must allow the cleaned and degreased iron to rust a little.

The really odd thing about them is they don't adhere particularly well to bright metal; you MUST let it rust, in order for there to be something to convert to ... whatever it is that they convert the iron oxide to.

The stuff usually goes on white, and dries black. The dried film is moderately corrosion-resistant by itself, but is really intended as a primer for a traditional paint system.

Things get complicated if parts of the workpiece don't rust; e.g. weld beads with a high nickel content, etc. The coating may not adhere as well as you would like to such things, and conventional blasting to white metal and regular primer would then be a better choice.



Mike Halloran
Pembroke Pines, FL, USA

 

[TomDOT]

Mike, I've never been impressed with those tannic acid "rust converters."