Cold Process Black Metal Oxide

[4156df]

I’m black oxiding a couple of parts for engine No. 3 and thought I’d pass on my method. This is a cold process and is very benign, particularly as compared to the industrial hot line black metal oxide process. Of course it’s not as durable or attractive either, but perfectly acceptable for my purposes.

I’m using Birchwood Casey’s (www.birchwoodcasey.com) Presto Black PC-9. I got mine from Industrial Metal Supply, a SoCal metal supplier, but it can be ordered directly from Birchwood Casey or one of their dealers.

Here’s what you need to get started.

Mixed solution. The product as supplied is diluted one-to-one with water. You just need enough to cover the part.

Part has to be clean. Use a good detergent and don’t touch the parts once you’ve cleaned them.

The part turns black as soon as it hits the solution. The manufacturer says to leave it for 1-3 minutes. I leave it for three. Time in solution doesn’t seem to be critical.

Once it’s pulled from the solution, rinse it with water to stop the reaction and let it dry. The part will have areas that look “smutty” and uneven…not to worry.

Burnish with 0000 steel wool. This will knock down the smutty areas and even the finish. The more you rub, the more oxide that comes off. I wasn’t looking for a dark color, so I rubbed quite a bit. If you want darker, just run it through the process again.

After steel wool, coat with a light machine oil and wipe down. This part is oiled, but if you want a glossier look, use wax instead of oil. I like black Kiwi Shoe Polish.

Here’s a part that’s had two runs through the process. The more times you run it through, the darker it gets.

Regards,
Dennis

 

[JohnS]

Hi Dennis

Does this product work on all materials including aluminium (or is that aluminum ?) and brass ? I have been looking out for a 'blackening' treatment for some time.

John S

 

[Hexbasher]

Go to a gunsmith shop or gun shop...they have (or should) have all different colors for all sorts of metals....i got a black for 6061, same idea.....but when i clear coated the parts, turned alil purple....but i blame the paint...ended up sending the parts off to be anodized

 

[4156df]

John,
The material shown is just for iron & steel. However, they do make something for blackening aluminum. I've never used it though.
Dennis

 

[Hexbasher]

Just noticed, is that your wife's nice bowl youre using for your mysterious alchemy?????

 

[Bogstandard]

John

Supposedly soaking brass in a paste of baking soda overnight turns it black.

Never tried it as I don't have anything to do with cooking, not my job.

I know you do a bit, let us know the results.


Bogs

 

[Circlip]

And if you're going to go down the black anodising of Aluminininum trail John S ( and it is the best long wearing route) check with the finisher which is the best SPEC of alloy to use, - some take better than others, and black is THE worst colour to pick according to the finishers I checked with, although it was some time ago.
Regards Ian.

 

[JohnS]

Thanks Guys

Some useful ideas there, I appreciate your input. My next project, which is still very much in the planning stage, is to build a single cylinder version of the Halo but adapted for the appearance of a 1930's 250cc Rudge motorcycle engine.

Whilst retaining the same basic operational dimensions I reckon I may be able to achieve the correct visual proportions by increasing the height of the cylinder head. Then its a matter of sculpture to achieve the 'look'. This is the reason I am interested in 'blackening' either aluminium or brass.

And John, you are absolutely right. I am chief cook and bottlewasher so have some experience in achieving a nice blackened appearance. Yorkshire pudding anyone ?

John S

 

[BobWarfield]

Lots of interesting metal coatings out there, and I really like experimenting with them. The liquids in a bowl are good for larger parts or larger runs of parts. For convenience on little "right away" projects, I like the creams.

Tatooed-Machinist is right about gunsmiths have all this stuff. For example, I tried a couple from Brownell's:

with this result:

The ones in the rear are the Oxpho-Blue while the one in front is Dicropan T-4. It's so hard to tell from a photo, but my conclusion was that the Dicropan looked darker, almost black, and seemed to go on more evenly. On the other hand, the Oxpho-Blue showed more blues and was a prettier finish despite it being less even. All things considered, I decided I preferred the Oxpho-Blue look.

These creams are so quick and easy. Degrease--I used rubbing alcohol and it worked great. Wear gloves or some other means of avoiding finger oil getting on the part. Wipe the cream on all over. Wait, rinse off. Done!

JohnS looks like neess some fine control to age a part. For that, I haven't experimented enough to say how the creams work.

Hot oil is another finish that looks great on this little machinist's jack:

It's not mine, but the fella said he put the part in his BBQ for 30 minutes and then plunged into 30W motor oil.

Cheers,

BW

 

[raym 11]

there are also some 'metal coloring' guides in Machiner's Handbook as well as Guy Lutard's Bedtime Readers

Ray M

 

[JohnS]

Thanks for the info and pictures Bob. This is really encouraging and I shall be researching equivalents at my local gunsmiths. A quick google on Brownells didn't bring up too much here in the UK but I am hopeful that there may be alternative options. I have come across a range of products under the name of 'Armatone' but I need to investigate further.

Thanks everyone for your replies. I shall report back when I have hopefully made further progress.

John S

 

[JohnS]

This looks promising, with products to treat brass and aluminium !
http://www.peterdyson.co.uk/acatalog/METALWORKING_PRODUCTS.html
John S

 

[Noitoen]

I know it's an old topic but still up to date. Came across an article on Popular Science that might come in handy http://books.google.com/books?id=oSkDAAAAMBAJ&printsec=frontcover&hl=pt-PT&source=gbs_atb#v=onepage&q&f=true Page 124. Those "old" chemicals might be hard to find nowadays but be worth while.