Blackening copper

I need to turn a bit of copper foil black. I have less than 1 square foot to treat. Paint isn't an option. Anyone know of a good way to do this? Google search wasn't real productive. I am wondering if any of the Birchwood gun stuff would work?? I tried using a sulphur paste, it tarnished it, but not black...

Thanks,

rog

Reply to
Roger Jensen
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I researched how to patina cast bronze black recently, didn't come up with anything. I wound up using a dark brown instead, looks OK. - GWE

Reply to
Grant Erwin

This is a VERY old memory going back to 8th grade art class, so don't take it as gospel, but as I recall it was sulfuric acid that would put a nearly black patina on copper. Then use vinegar do stop it and neutralize the acid.

As I said, please just use this a starting point...it might be the right stuff, but then again, it might not.

Mike

Reply to
The Davenport's

I don't see how vinegar would neutralize an acid since vinegar is an acid, isn't it?

Reply to
User Example

Try a Froogle search for " black patina on copper " , many choices.

Bruce

Reply to
Bruce Johnstone

Liver of Sulphur, from a craft shop.

Steve R.

Reply to
Steve R.

Did you miss this part of his post?

But yeah, you're right that vinegar (acetic acid) won't neutralize sulphuric acid worth diddly. Lye, baking soda, crushed limestone or gypsum (or all of the above, if you like) would do a good job of it, but one would want to be *REAL* careful, particularly with the lye, to avoid getting it flung back in one's face by the reaction.

And sulphur figures into the equation, but I can't recall how. All I remember is that the stuff we used when we did copper impresssions (I think mine was about 6th grade - Not sure. I remember that I did a motorcycle, though :) ) stunk to hell and gone of sulphur. Had to do that part outside on the benches around the courtyard, the stench was so bad. It ws safe enough to give to youngsters our age, so it couldn't have been *TOO* toxic beyond the smell.

Hmmm... on second thought, that *WAS* 25 years ago... When kids routinely did things like "chickenfights" on the monkey bars, shooting off model rockets, swimmming in The River, shooting the bejeezus out of the blackbird and crow population for miles around, and similar things that we now know are life-threatening activities sure to lead to the extinction of the human race. Who is it with the .sig that mentions "Used to be we made things a boy could lose a couple fingers on"? :)

Reply to
Don Bruder

What?.... No Marines in the group? Ask any jarhead about brass black~ I truely believe it would do the trick...

And Semper Fi, guys....

Bill

Reply to
BillP

Try liver of sulphur, but don't leave it on long or the oxide will get too thick and flake off.

Richard

Roger Jensen wrote:

Reply to
Richard Ferguson

I have "THE BOOK" on that - and have lots of blacks. How black - Which black? !

Semi-matte/matte Variegated black Semi-matte Dark slate with purplish tint Purplish-black black dark reddish brown black dark slate black semi-gloss dark slate/blue-black Blue-black Gloss Black semi-matte Black semi matte (2) Dark brown/black Black / dark slate

and several more pages..

Give me an idea of what black - is it for ? and I'll give out one. This book "The Colouring, Bronzing and Patination of Metals" Richard Hughes $53.55 Amazon.com lcccn 90-498660

Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH, NRA Life NRA Second Amendment Task Force Charter Founder

Roger Jensen wrote:

Reply to
Martin H. Eastburn

Mix and heat the sulphur into 10 parts turpentine until it is dissolved completely.

Brush lightly onto clean copper.

Heat the copper SLOWLY until black.

Reply to
bw

Gypsum is just calcium sulfate isn't it? If so, it's already a salt and won't act as a neutralizer.

Reply to
Mike Henry

D'OH!!! Where the heck did I get that? You are indeed correct.

Yep, absolutely true. My brain-fart.

Thanks fer "keepin' me honest". :)

Reply to
Don Bruder

Sulfuric acid will clean the oxide off the copper and it will be bright and probably frosty. If I remember correctly it's liver of sulfur your talking about and yes it stinks. Don't remember it's chemical name and don't remember if it turns copper black. Karl

whitelist,

"PopperAndShadow"

info

Reply to
Karl Vorwerk

Martin,

Semi gloss...

thanks,

rog

Reply to
Roger Jensen

I believe it is hydrogen sulfide

Reply to
Don Stauffer

THAT'S IT!!!

Thanks, Karl...I just KNEW that sulfur was in there somewhere!

I guess it's been a LOT longer going back to 8th grade than I thought...I'll blame it on the drugs...yeah, that's the ticket...aspirin will do it every time. :>

Mike

Reply to
The Davenport's

One way to get these chemicals - if you know a druggist - or a chemical company... A druggist can order these in small liter sized bottles - or less. I say take this - as the real names are here - the real purpose is here and you might not have to worry with permission blank from the FBI or Homeland Security... The first is IIRC used in a photo lab - I want to say developer - not sure. Been a while since I taught that! Ferric Nitrate - just have to order. Not simple off the shelf stuff. I don't think a ranch and farm supply would have either. Here goes - and good luck. The book is expensive - in a way - but 360+ pages of data - most of it like this :

" Copper / Copper Plate Black

3.111 Black Semi-gloss Sodium Thiosulphate 50 gm Ferric Nitrate 12.5 gm Water 1 liter

HOT Immersion (Twenty Minutes) [ bad info first :-) If the temp is to high the color layer will be patchy and more fragile when removed from solution, revealing a tan color beneath the black. ]

Method : The article is immersed into the hot solution - 60-70C - and after about 1 minute the surface is colored with a purple-blue luster, which gradually recedes. After 5 minutes a brown color slowly appears which changes to a slate Grey with continued immersion. After about twenty minutes the article is removed, washed in hot water and allowed to dry in air. The surface may be fragile at this stage and should be handled as little as possible. When completely dry the article is wax finished. " quote from page 190 "The Coloring, Bronzing and Pagination of Metals" ========================================================================= (spelling changed from British English to American English )

Martin

Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH, NRA Life NRA Second Amendment Task Force Charter Founder

Roger Jensen wrote:

Reply to
Martin H. Eastburn

Odds are that you were using "Liver of Sulfur" (POTASH SULFURATED). It's been the standard stuff for darkening copper and bronze for donkey's ages now. I bought some a few years ago from a crafts supply shop. It came in powder form, to be mixed with water. And yes, it does have a very farty smell to it.

It does a good job of "antiquing" copper and brass stuff, and can't be too hazardous, as I've gotten it on my fingers plenty of times for a minute or so, and they didn't fall off or anything.

Jeff

Reply to
Jeff Wisnia

Reply to
David Billington

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