Sciencemadness Discussion Board

Garden Sulfur for Oxidizing Copper?

Bane - 8-11-2011 at 10:03

Hey all,

I'm making copper jewelry, and I would like to oxidize some of my pieces. I know about "liver of sulfur", which I understand is Potassium Polysulfide, or sulfurated potash. You dissolve it in hot water, then soak the metal. However, I can't find a local supplier, and I have a show in a few days, and I'd rather not have to pay for overnight shipping to get the liver of sulfur.

So I was looking around online, and found this stuff called Garden Sulfur (or lime sulfur? not sure if they're synonyms) that's available at Home Depot and Lowes garden centers.

What I'm wondering is if this stuff might work to oxidize copper instead of using liver of sulfur if I dissolve it in water.

I don't know a whole lot about chemistry, so can somebody help me out?

Thanks!

Polverone - 8-11-2011 at 10:08

Lime sulfur is worth a try. It too contains polysulfides. Garden sulfur is likely to be elemental sulfur mixed with conditioning materials -- not at all the same thing. Be careful working with lime sulfur indoors: it will emit some hydrogen sulfide, and hydrogen sulfide is both very poisonous and capable of disabling your olfactory warnings with high or prolonged exposure. You may want to do your work in an open garage or other place where air circulation is abundant.

Bane - 8-11-2011 at 10:22

Thanks for the speedy reply :)

I plan on doing any oxidizing outdoors on the balcony, so I'm not too worried about fumes building up.

I just looked up the msds on the garden sulfur, and it looks indeed as though it's 90% sulfur, and the last 10% is "inert diluent and anti-caking agent".

I'm not sure that Home depot or lowes carry lime sulfur though, so I may be forced to pay exhorbitant overnight fees anyway, haha.

Thanks again.

Sedit - 8-11-2011 at 18:48

http://www.mailleartisans.org/articles/articledisplay.cgi?ke...

Ammonia chloride is everywhere and will get you your results in minutes from the looks of it.

Twospoons - 8-11-2011 at 18:56

Yes Lime Sulphur definitely works - I've used it for that purpose myself. I usually add a bit of potassium sulphate (also available at the garden shop) to create some potassium sulphide in the solution, makes it work a bit better. You will have to play with the dilution to get it to work well.
Don't get confused with the powdered sulphur (flowers of sulphur) - it is not the same thing. Lime sulphur is usually sold as a liquid, and is a solution of calcium polysulphides - it has that characteristic rotten egg / farty smell.

Bane - 9-11-2011 at 07:55
Quote: Originally posted by Sedit  
http://www.mailleartisans.org/articles/articledisplay.cgi?ke...

Ammonia chloride is everywhere and will get you your results in minutes from the looks of it.


Thanks for the link :)

I actually frequent mailleartisans.org and was not aware of that page. That being said, I'm afraid that ammonia chloride produces too "green" of an oxide for my purposes. Potassium polysulfide somehow produces a blackening of the copper, while still allowing the metal to shine. The effect is really quite nice-looking.
Quote: Originally posted by Twospoons  
Yes Lime Sulphur definitely works - I've used it for that purpose myself. I usually add a bit of potassium sulphate (also available at the garden shop) to create some potassium sulphide in the solution, makes it work a bit better. You will have to play with the dilution to get it to work well.
Don't get confused with the powdered sulphur (flowers of sulphur) - it is not the same thing. Lime sulphur is usually sold as a liquid, and is a solution of calcium polysulphides - it has that characteristic rotten egg / farty smell.


It's good to hear that someone has already successfully used lime sulfur for this purpose. Which color of oxide does it produce? I'm looking for the blackened effect, as opposed to the green powdery stuff. Did you get these chemicals at Home Depot/Lowes garden centers or where? A search for "Lime Sulfur" on their respective websites returned no results. Is it a seasonal product? How about the potassium sulphate?

Thanks :)

ScienceSquirrel - 9-11-2011 at 08:03

I suspect that you could make a make a polysulphide solution suitable for your purposes by boiling sodium hydroxide ( lye, caustic soda ) solution with garden sulphur.
I would be careful as it will be toxic and corrosive.

watson.fawkes - 9-11-2011 at 09:33

I pulled out my copy of The Colouring, Bronzing and Patination of Metals, which is a compendium of recipes for exactly what you're looking for. In the chapter for copper and copper-plate, in the section for the color black, most of the recipes involve sulfur of one kind or another. There's one involving sodium thiosulfate and copper sulfate, both over-the-counter chemicals. Dissolve 125 g of sodium thiosulfate in 500 cc water. Dissolve 50 g copper sulfate in 500 cc water. After separate dissolution, mix these solutions together. Immerse in cold (unheated) solution for two hours. Copper sulfate is available as root killer. Sodium thiosulfate is available as a chlorine scavenger for swimming pools and aquaria.