Blackening nuts and bolts?

Don't know if I have posted this in the right place...

Is there a way (or a product) for blackening steel nuts and bolts etc to give them a 'newish' look?

I know you can chemically blacken brass (at some expense!) but not sure about steel???

Michael

Heat them to cherry red then dunk in waste oil.

I soak in old dirty gearbox oil for a few minutes and then bake in a hot oven. Repeat to get them darker. Beware if you use the wife's oven, it smells.

Stu (sorry, wasn't Stu who said it at all, it was Villiers. I just saw a little red engine in the avatar pic) has already said the correct way to "oil black" things. In engineering it is called "Oil Blueing" & is used with a special, clean oil which has a high flashpoint, but I don't know where you'd get that from. Oil Blacking is more of a blacksmiths practise & is always done with waste engine oil, as it gives a darker finish. They are both a recognised engineering practise to protect new metal & were often used by tool makers etc. I was taught how to do it when I studied engineering at college.

Personally though, I use some stuff called "Hammerite Kurust" (other rust converters are available, & are probably better). As it doesn't involve heating stuff up & dipping it in oil, risking a fire. But for this stuff to work properly the nut or bolt needs to have some rust on it & it needs to be completely de-greased. I use it a lot on my engine projects, I also use it on cast iron barrels to blacken the fins on air cooled engines & on exhausts as well. Right now I have a load of Lister A nuts, bolts, bits & bobs sitting outside, which I have cleaned in parts wash, rinsed in brake & clutch cleaner then washed again in a water based de-greaser & left to get a coating of surface rust ready to treat. (usually just a clean off with brake & clutch cleaner is sufficient).

Kurust is water based & won't take if there is any oil or grease. Also it converts rust on ferrous metals & turns black, so if there's no rust, it won't go black & doesn't look right.

I would advise anyone to get a bottle of rust converter (not necessarily Kurust, I believe ToolStation do a very good one) anyway as it's very handy stuff. Give it a try.

I also used it on some cast iron carb parts. Once sprayed with a petrol proof lacquer it has a lovely finish. It's probably petrol proof anyway, but everything was getting sprayed & that just happened to be there. It looked really good.

Here's an exhaust treated with it (it does lose it's shine quite quickly, it's not really a shiny finish, more a dull finish)....



& here's that carb I was on about (but before it got it's coat of petrol proof lacquer. All the lacquer did was give it a lasting gloss shine)....



Hope this helps a bit, now you've got 3 sure fire ways of blackening your nuts (& bolts). I've never used the oven method, but it sounds good to me. I'm unlikely to use it though as my life would not be worth living!

Oh yes, I forgot to mention, you can also use vinegar for this. My brother knows all about it, apparently it helps to temper the metal as well.

just ordinary Sarsons (other vinegars are available) malt vinegar, like you put on your chips, put straight on the cold metal (I think). 

I'm told it works a treat.

There's probably other ways as well.

That stuff looks like the stuff Abs uses on his engines. You know the stuff for the fires. (If I'm correct)

No, it's not the same stuff, but you could use that. I have used it to make things go black before (like a Tarpen exhaust which had patches of old chrome on it).

The stuff you mean is "Black Grate Polish", or "Stove Black". It's a type of polish. What Abes does (I think) is paint the engine first in blackboard paint (matt black), then, once dry, polishes it with the Stove-Black. It gives a lovely finish, I painted one of my engines like that once....

Here's some bits I did for the Lister a couple of evenings ago....





Best to wear gloves when using Kurust thogh, it takes days to get off your hands, even with proper commercial hand cleaner.

For blacking smaller components, there is a product available from model railway suppliers, it's by a company called Carrs, check out www.finescale.org.uk for more info.

Thanks for that. I had a look round & found they have a few different metal black treatments in their chemicals category. Here (hopefully) is a page with them on it....

http://www.finescale.org.uk/index.php?route=product/category&path=440

Yes, I have used this when rebuilding cameras but only ever tried it on brass. very nice finish on small components.

I've just been reading an article in one of the classic motorbike magazines about this. Someone on there has been using the electrolysis method of rust removal on cast iron parts, then he dunked the part in a bucket of Coca-Cola (not the cheap supermarket stuff the real McCoy) & left it in there for a couple of days. It came out looking something between oil blacked & oil blued.

Might be worth a try, maybe just a can of coke & a jam jar. I expect the parts need to be thoroughly cleaned & de-greased before. I know Coke is quite corrosive to metals & can be used to un-seize pistons in bores (it used to be a sworn-by method of un-seizing old engines). I wouldn't recommend leaving parts in the stuff indefinitely though, I've known it to eat through cast iron (obviously after quite a long time). But I think I will try some experiments with it myself.

...and someone once said diet coke is even better.

I have certainly cleaned bits if rusty car back to metal with coke but never had a 'blackened' finish. Will give it a try

The guy in the article left the part in there for 2 days. Maybe that has something to do with it, maybe it's just something to do with the fact he'd just de-rusted it using electrolysis (12v battery charger, bucket full of washing-soda-in-water solution & a lump of old iron, it's quite an easy process although I haven't tried it myself I know at least one other forum member uses it regularly, there is a link somewhere on the forum explaining the process in greater detail). Maybe the de-rusting prepared the metal in some way, it is an alkaline process & I think Coca-Cola is an acidic substance, but that's about as far as my school-boy chemistry goes I'm afraid.

I've got to go to the shop in a moment & get some tobacco, maybe I'll pick up a can of coke while I'm there. I certainly wouldn't drink the stuff, can't say I'm a fan of it, to me it would be put to far better use in the workshop.

Perhaps a can of diet as well. Maybe the lack of sugar & those awful, toxic artificial sweeteners have a different effect.

Diet Coke test already underway. Went in at 4pm today, will check in 24hrs.

Beat me to it then. I went to the shop & they had a deal on coke, the bigger bottles, any 2 for £2.50, so I got one diet & one full-fat. Will give it a try when I've cleaned up a few of the Bamford nuts & bolts.

Diet Coke is working. After 24 hrs the rust has gone. I will leave them in another day and report back!

sorry I have held back long enough,
there is only really one way to propperly blacken nuts, with a hammer

coke contains phosphoric acid which is the ingredient in most rust killers.

Has anyone tried to clean up an engine using phosphoric acid?

http://www.ebay.co.uk/itm/SUPER-STRONG-42-PHOSPHORIC-ACID-BEST-RUST-REMOVER-DESCALER-/260884262016?pt=UK_BOI_Restaurant_RL&hash=item3cbde9ec80

Stu.

Not used it myself Stu, although I think it's the main ingredient in Kurust.

My Coca-Cola experiments have kind of gone on hold since I found a large glass & a load of ice cubes  

nutgone wrote:Not used it myself Stu, although I think it's the main ingredient in Kurust.

My Coca-Cola experiments have kind of gone on hold since I found a large glass & a load of ice cubes  

    Nuts. Just have to buy cheap coke that tastes sh1t    

Stu.

2 days are up. Diet coke job is done. They may not look brand new but they are a hell of a lot better. I will desist from drinking what's left.

Did you de-grease them first?

Has this just de-rusted or has it successfully changed colours.

I've got a load of bits & bobs off the Bamford which could do with soaking, but they are caked in old oil & grease.

(I haven't drunk much of it, maybe I'll get another couple of bottles in the next few days, as I'll have to go back down the shop for some filter tips (I do live the high life you know, if it wasn't for my smoking & various hospital appointments I would never get out of the house).

Things have to be degreased 100%. I know because fingermarks show. It has de-rusted and blackened things a bit which tidies them up but I have no idea how permanent the effect is. Just chuck a couple of clean bits in a jug and forget for a day or two.

To be honest, the result is not as satisfying as I had hoped...