Raw steel.

[Science]

I'm contemplating stripping my fixxie down to bare metal, putting it in the back yard and letting it rust for a bit, then rebuilding it with tonnes of chrome and billet. But im wondering if there is a way to limit the amount of rust I get to prevent it becoming structural.
Once it's built, I will be keeping it indoors, but i plan to ride it regardless of weather.

Also the bike is an SE Lager

 

[Larryscustomcycles]

You can just let it rust and then clear coat it...but you probably wont get the finish you are after.

Try this:
http://www.haymespaint.com.au/haymes/main.php?c=170

then...

http://www.haymespaint.com.au/haymes/main.php?c=165

You will get a better, more consistent finish.

If its good quality steel (like 4130 or better) everywhere, not just the main triangle & hi ten for the rest then you could strip it, rust proof the inside then build it and ride it, that way you will get all sorts of unique stains (from crap on the road, sweat, beer etc). Just give it a wipe every now and then with a light oil.

 

[muvro]

You can actually buy rust effect paint. The Film industry use it on cars for TV/movies etc. Where to get it I wouldn't have a clue... But it's a start point.

 

[brendonj]

Even rust effect

If the fake rust paint effect mentioned above is not an option....

Haven't thought this through heaps, but the basic principle is moisture plus oxygen... So, you should probably do it outside but under cover, but artificially regularly apply an even amount of moisture - ie with a hose or a wet towel, taking care not to get puddle on any parts. If areas are going faster than others than you could adjust your moisture application appropriately. This should assist in achieving a reasonably even outcome. Note I have never done this before my self.

Because it is probably a reasaonably high alloy steel, the corrosion rate will be slower than normal steel. This should help after the event to prevent your frame falling apart.

But you must also be aware that the fatigue strength of the frame will be comprimised significantly by the presence of corrosion. So keep this in mind if you go down this path.

 

[davemchenry]

Rust it and Ride it

I have ridden old Schwinn Cruiser bikes from the 50's and 60's for a long time and while I have a few show bikes my daily driver is a rat rod rusted to the bone, I let it rust and put bees wax over it and i'll rider her forever. Steel is real!

 

[Nerf Herder]

Fake rust paint coupled with some sticker action

 

[PJS]

I wanted a rusty finish to a golf club head of mine (designed to rust overtime and give better back spin rah rah....)

I sped the process up by having it in a salt bath for a few hours with a current speeding up the process. Think I used a couple of AA batteries and alfoil as the wires. Taped it up with making tape.
I'd imagine if you had a tank big enough you could do the same. The advantage is its completely even in finish because the whole thing will be in the same concentration and the same current. You also have complete control of when to stop.

(You'd set this up by having one wire stuck to the frame which is completely submerged, and the other end just secured beneath the solution below the water line. Doesn't have to be extremely salty - just enough to have the current from the power source flow)

 

[redbruce]

I wanted a rusty finish to a golf club head of mine (designed to rust overtime and give better back spin rah rah....)

I sped the process up by having it in a salt bath for a few hours with a current speeding up the process. Think I used a couple of AA batteries and alfoil as the wires. Taped it up with making tape.
I'd imagine if you had a tank big enough you could do the same. The advantage is its completely even in finish because the whole thing will be in the same concentration and the same current. You also have complete control of when to stop.

(You'd set this up by having one wire stuck to the frame which is completely submerged, and the other end just secured beneath the solution below the water line. Doesn't have to be extremely salty - just enough to have the current from the power source flow)

Industrial designers use Hydrochloric (aka muriatic) acid to create rusted architectural finishes. There is plenty of info on the web on how to do it.

 

[whoateallthepies]

I know someone who did this to a singlespeed roadbike (Lee Cooper custom frame).

He basically just let it sit outside for a few weeks until it looked the way he wanted it, then had it clear coated to preserve it.

Here is the finished bike:

Cooper 8 by Singlespeed Pimp, on Flickr


The look is hard to capture on camera, here is a close up

Cooper 3 by Singlespeed Pimp, on Flickr
The rust is superficial and should have absolutely zero impact on strength or durability. It would not surprise me if your frame already looks like this from the inside, unless it was filled with a frame preserver when new.

Word of warning - the clear coat will not last as long as on a properly primed frame, so expect to re-paint it after a few years.

Another option is to not paint the frame at all, and use a protective oil to preserve it. This has to be reapplied every so often.