Chemical blacking

[Chipper]

Is DIY blacking any good? Wondering where it's worth doing on some fasteners on my bike.

Don't want shiney ones i.e. stainless replacements. Black is the new black. And some aren't ones you can buy from a fastener shop.

It seems to depend on the dewatering oil which doesn't sound great for rust resistance, bearing in mind it'll be ridden in all weathers so will face road salt etc?

 

[drivewasher]

You can get a metal blacking solution its intended for blackening the hob elements on electric cookers. Try electrical appliance spares shop

 

[gordon stephenson]

Why not try the oil blackening method, I have used this many times, simple,quick and CHEAP. fix a wire to your parts, heat with a torch and dip into a container of old engine oil.keep repeating this until you have a nice satin black finish to your fasteners.You don't need to get the metal too hot just dip and keep reheating, etc, try it on a piece of scrap first to get the feel for it,
Just got to add for "H&S" be carefull, torch flames + oil etc.

 

[shenion]

I use the oil blackening and it works well. I recently made some wheel axles out of mild steel (basically a bolt with a shoulder on it.) Heated with propane torch and dipped in oil.

No rust and still looks good.

 

[astro_al]

I'm making something out of stainless (combo of 304 and 316) at the mo, and it could use being 'blackened' - does the old oil trick work on s/s does anyone know? Cheers, Al.

 

[gordon stephenson]

Hi Astro Al
Never ever tried it in stainlees, but cant see why not, It's only the burning oil carbonising on the heated surface, give it a try won't take long and nothing to lose,
First time I used it was in the school metal work class when I was about 13 to protect a centre square I had made, square hanging up in my garage now still rust free and I'll be 65 in december,
Cheers Gordon.

 

[AndyP]

Don't waste your time on cold blacking it is truly rubbish. Take your part to a metal finisher and get it done for peanuts.

All cold blacking solutions do is coat the steel with a thin layer of copper and the chemicals black that. Then in a few weeks it all goes rusty unless you also purchase one of the sealing kits they will also sell you which is just overpriced thin varnish that puts off the inevitable for a bit longer.

Sorry!

 

[Chipper]

Thanks Andy, no, thats just what I needed - good/bad etc. I've got quite a few to do hence wondering about the dip. The heat/oil thing would take a while plus some I wouldn't want to heat (brakes). Will look into to the farming out bit. Cheers all.

 

[Ratty]

Why not try the oil blackening method, I have used this many times, simple,quick and CHEAP. fix a wire to your parts, heat with a torch and dip into a container of old engine oil.keep repeating this until you have a nice satin black finish to your fasteners.You don't need to get the metal too hot just dip and keep reheating, etc, try it on a piece of scrap first to get the feel for it,
Just got to add for "H&S" be carefull, torch flames + oil etc.

That's a great tip Gordon, I shall try it on my next sculpture that has to withstand the elements. Have you tried spraying the oil on? just thinking about treating a piece that's too large to dip..

 

[Paul.]

Be carefull spraying oil onto hot metal, it's more likely to burn, dipping into a pot of oil quenches, although if you're doing a few pieces and the oil gets hot it may still catch fire, if the oils contained in a pot is easily put out with by covering with a lid. for very large areas brushing might be better.

 

[gordon stephenson]

Sorry Ratty, only ever made small enough item to be dipped completely.

 

[Ratty]

Be carefull spraying oil onto hot metal, it's more likely to burn, dipping into a pot of oil quenches, although if you're doing a few pieces and the oil gets hot it may still catch fire, if the oils contained in a pot is easily put out with by covering with a lid. for very large areas brushing might be better.

Good point..I was thinking of how patina is applied on bronzes but you're more likely to choke on the fumes then cause a fire. Brushing would probably wreck bristles pretty quick but maybe sitting the piece in a metal container and pouring the oil over would work. If I get around to trying I'll report back

 

[hareng]

Theres a bit of an art to oil blacking, you dont want any runs else it will leave a burnt bubble.

Nicest and easy to do is the colour hardening method, you can choose the colour. Works on stainless G303, 304, 316S11 as well.

Cold blacking waste of time, its only for touching up very small screws and dont last long at all. Its a rusting process same as hot blacking salts to get the colour as well.

 

[gordon stephenson]

Hi Hareng,
I have oil blackened things numerous times and never yet had any hint of trouble with oil "runs" etc. its just a gradual process of heat-dip,heat-dip until the surface reaches the finish you are looking for, satin black smooth and rust resistant.
Cheers Gordon.

 

[Ratty]

Nicest and easy to do is the colour hardening method, you can choose the colour. Works on stainless G303, 304, 316S11 as well.

Can you enlighten me on what this involves? I did google but couldn't find much of use (something about bone meal and burnt leather which sounded very complicated!) any links to useful sites would be appreciated. Thanks

 

[brightspark]

why dont u get them black chrome plated its hard as hell and doesnt rust

 

[hareng]

Now you are talking black chrome plated, not many places that do that and could be over 300 degrees required so if thats the case will be too soft.
Normal chrome platings far less and used on plastics ie Rover and Ford at two places in UK.

Depends upon looks if you want a shabby finish dip in oil, it hides 2nd cut file marks. We only do it on cheap products to hide above and show its been hardened and blazed off. Oil we use for that purpose whale oil burns at 200+ degrees. Sure bearing oil for hardening burns at 150 degrees, this can leave a decent finish but flakes off.

 

[hareng]

Technically its not colour hardening as bone meal can be used sure this gives off arsenic so wouldnt advise. Only tried it once and did a runner quick plus it was no good. Careful dont breathe and wash hands rigorously.
All of this work is kept a closely guarded secret and only a few worldwide have perfected and know how to charge.
Search for Smith and Wesson in the US though they did alter the process after one of the workers died.

An easy way to get a good quality colour is by heating the metal up evenly. As you know when welding to the side of the weld laid it will have coloured the metal. Mild steels start at 230 degrees will be translucent brown, whilst colour goes out at 285 degrees light blue.
If you get it 250 probably purple to 275 dark blue, guessing. Its good enough for the screws on £45k products after a service, that should give you some idea, other than that they would be hot blacked.
Screws and small items very easy, long items take some doing but often settle for going through the colour spectrum over the length. Even then may take a few attempts.

 

[Shox Dr]

I posted a similar question sometime ago. Have a look a the thread, after some rooting about I found some good links

 

[English Steve]

I have also used oil-blueing a number of times with good results. First did it while at school in metalwork class - we made a set of tyre levers and blued them. I still have the levers and they have never rusted.
Like Gordon, I have never had any problems with blisters on the surface or anything like that. The only problem these days is that the modern oils don't lend themselves to the process as readily as the older oils did because the carbon content is much lower now.
It's a very easy and reliable surface finishing method which will stand up to considerable abuse.