Chemistry types - Will this work?

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Chemistry types - Will this work?

12 posts & 9 voices | Started 1 year ago by bedmaker | Latest reply from bassspine

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bedmaker - Member

I have an old but nice reynolds road frame which I have built as a fixed. Thinking of giving it a paint but I quite fancy a trying a distressed rusty look as seen on old hot rods in California.

I'm thinking, sandblast it, spray with vinegar and allow to surface rust for a while then put in a warm cupboard with a dehumidifier on.
Take from said toasty cupboard then immediately laquer with 2 pack.

Will

A) the rust be trapped there, oxygen and moisture free and stay like that indefinately?
B)something else bad happen?

Posted 1 year ago #
PaulD - Member

Bedmaker,

This will be a disaster with a slow fuse.

The water (and other oxygen) will be trapped and will continue to oxidise the iron at a rate of approx 0.2mm/year until you get a perforation or fatigue failure from the reduced cross section of metal.
Ferrous oxide is not protective or passive, but actually occupies a larger volume than the metal (unlike magnesium oxide), thereby bursting the lacquer and letting more oxygen and moisture reach the metal.
In addition, any coating that dries by solvent evaporation is leaving a porous layer that allows moisture and oxygen to reach the metal, hence low-baking or powder coating to provide a seal.
Your process is not recommended.

Posted 1 year ago #
Frankenstein - Member

Is it possible to spray decent primer, then spray top caot as close as to metal colour and mix in some iron granules.

Let that rust instead and lac that instead.

Try on a small test piece and see what happens.

Posted 1 year ago #
thisisnotaspoon - Member

IIRC those hot rods are either done in California, i.e. there's no moisture so you can cafrefylly regulate the rust, and its only on cosmetic pannels. or done with rust paint, which is actualy not too disimilar to zinc primer so protects the metal underneath whilst looking completely rusted.

Posted 1 year ago #
Nicknoxx - Member

If you get the frame dry then manage to seal it with lacquer, no more rust can form. Any water that was used to make the rust will be tied up chemically and not available to make more rust. It's a reagent not a catalyst.

Posted 1 year ago #
thisisnotaspoon - Member

If you just clearcoat it with a solvent based laquer it will 'rust' through it over time as paulD says, like the 456 summer season did/does. I wouldnt let it rust then spray it though, the rust isnt strongly bonded to the metal, so the paint wont stick properly and will peel off.

Not quite sure where he gets 0.2mm/year from though, bear in mind bike frames are not much thicker than that and will quite happily live unpainted for years?

Posted 1 year ago #
bedmaker - Member

thanks guys

It wasnt something I really had my heart set on and it is a quality frame so I think Ill give it a miss.

Might try it on a scrap tube though and leave it outside, just to see.

Posted 1 year ago #
bedmaker - Member

also can't believe this hasn't attracted more mockery and derision, why haven't the forum arseholes picked on me

Posted 1 year ago #
crazy-legs - Member

Rob Hayles (top UK road/track rider) did something very similar on one of his old steel frames, it looks really good.

He left his in the garden for a year but your method should work (I'd use water insead of vinegar though).
Rubbed it down to get rid of the surface flakiness then laquered it.
You'll probably need to re-tap the threads and maybe ream out the seat-tube as well depending on how much it's rusted.

Posted 1 year ago #
Quirrel - Member

I've seen the rat look on cars sealed with engine oil. - just found this one in my emails

• No paintwork to polish, 100% genuine rust finish (Sealed with old engine oil for environmentally friendliness)

Posted 1 year ago #
jonb - Member

Have a play you may not need vinega to get it to rust. Acetic acid is suprisingly corrosive. Water and about 48hours is normally enough to get surface rust for my tests in the lab.

As above really once it has started to rust it will continue under the lacquer. Also the lacquer may not stick very well to the rust or the rust to the steel meaning the paint will come off quicky. Id suggest you'd have more luck with a rust coloured paint.

Posted 1 year ago #
bassspine - Member

can you get clear powdercoat?

Posted 1 year ago #

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