I'm planning on building a table which will use copper plumbing pipe as one of its parts. I want to patina this to a green shade like copper gets when exposed to the elements. Searching I see there are recipes for solutions to do this, as well as some pre-made products. I'm wondering if anyone here has any experiece with this, and can suggest particular products/procedures.
TIA
Dan
I am interested in this, too. IIRC, from previous discussions, the green color is from exposure to acid. Weak sulfuric, I believe. Common name, muriatic acid. Other colors are obtained from different solutions. One of the solutions called for in one of the recipes is acetic acid, common name, vinegar. Another ingredient is copper nitrate.
BE CAREFUL. Working with acid is very dangerous. About the most important thing you need to know is:
ALWAYS ADD ACID TO WATER, NEVER WATER TO ACID.
Adding water to acid produces heat. I have seen chemical demonstrations where a 4" diameter two foot high glass vessel shaped like a tube was filled half full of acid. A small amount of water was added. The glass shattered at the liquid line.
So, if you are going to use the really nasty stuff, like muriatic, always add the acid to water.
I was considering making a rack that would sit in one of the big plastic tubs. The rack would be plastic. Full strength muriatic acid would be added to the tub, until about 1/2" deep. The copper workment would be placed on the rack. The cover would be placed on top, and left. The idea being that the vapor from the acid would float up and patinate the copper. A wading pool could also be used, and perhaps instead of using so much acid in the bottom of the pool, one could place several shallow plastic dishes of it instead.
I have seen real copper that was left out in the elements. Old chimney pieces, rain gutters, old house trim pieces. It all had lovely green patination, indicating that it was something in the weather that did it. I suspect acid rain.
Try some vinegar. Try some acid, but just be careful. Wear safety glasses, and have a hose or water bath ready in case you do get some on you. (I guarantee you will.) Read some of the thousands of ads on Google, or search newsgroups for arts and crafts.
I'll be following this thread, as I intend to use copper on some projects.
Sorry I can't be more help right now, but I'm learning, too. There's just so much to be learned.
Steve
Google verdigris.
You're spreading hearsay, not something you've actually experimented with, right? What you say is not true. You can pour water into full strenth pool acid (31.5 percent hydrochloric) without a problem.
Now sulfuric acid, that will blow up in your face if you try that.
Read the warning label on a bottle of Muriatic acid. It will say to add the acid to water to avoid splashing.
I think you can do this by placing the copper in water with some salt added.
Attach a jumper cable from the positive side of a car battery to the copper and the negative side to something made of galvanized metal that is also in the water.
The flow of electrons from the copper to the zinc should put a patina on the copper rather quickly.
Note: this should be done with DC current AC will not have the same effect.
And the container for the water needs to be non conductive.
I've never tried this but I've always wanted to.
If you do please let me know how well it works.
Muriatic acid is hydrochloric, not sulfuric. They'll produce different colors. Copper chloride is green, copper sulfate is blue.
Speaking of spreading hearsay...
You go right ahead and do that if you want, but advising others of the (supposed) safety of a practice that every chemistry instructor and laboratory safety guide warns against, is stupid and irresponsible.
Hi Dan,
If you're doing just a small area you can get the patina product from a Hobby & Craft store. I want to say it runs around $7.00 a bottle.
I think it would be safer to use than just buying and mixing your own acid.
I have in my cupboard right now a bottle called "Patina Blue" it's made by Modern Options Inc.
2325 Third St. San Francisco CA 415-252-5580 It works on copper, brass and bronze.When you're doing this, be sure that the surface is completely clean and free of oils and fingerprints. I prefer to use a cotton ball to apply it or something like a bit of cheese cloth. If you kind of rub it into the surface then wet it well, it gives a GREAT looking finish.
It will take a day or two to achieve the rich patina of age and it can be reapplied over the initial finish if you miss a spot.
I believe it comes in other colors as well.
FYI it will rust nails and screws made of anything other than copper, brass or bronze. Even the plated ones.
Hope this helped!
Kate I posted a photo for you on the binary group, my server rejected it... go figure.
TIA
Dan
The advice is sound for sulfuric acid. For hydrochloric, it is just superstition spread by repetition. To their credit, not "every chemistry instructor" or guide is quite so credulous, although generally they do spout this "conventional wisdom." But it is just wrong in being overgeneralized to all acids.
I don't expect you to believe me. Just try it yourself, if you have the courage. Otherwise, you just compound the ignorance. Come to my place, and you can experiment at my expense with the gallons of HCl I pour into my pool.
The truth is never stupid or irresponsible. Your feelings are hurt that you didn't know this little fact, and were gullible enough to believe the overgeneralization you'd been taught.
Neither of the two brands I use (Smart, Allied Universal) say that on the bottles. Lots of warnings about corrosiveness and burns, but nothing about diluting being hazardous, because IT ISN'T.
Kate-Thanks for the info. I think I'd prefer to use a pre-mixed product, unless the cost is really high. I'll look into the brand you suggest.
Dan
Richard-Thanks for the link, interesting thread. If I can find a pre-mixed solution of reasonable cost I think I'd prefer it though.
Dan
"Dan" wrote
Kate-Thanks for the info. I think I'd prefer to use a pre-mixed product, unless the cost is really high. I'll look into the brand you suggest.
Dan
Best of luck to you Dan, would LOVE to see the results :)
Kate O||||||O
It's a generalized rule for mixing water and any acid. It may not be neccessary in the case of HCl, but since being consistant doesn't cost you anything and does reduce the chance of getting it wrong with other acids, most people just tell you to do it that way always. There is simply no value in itemizing the exceptions. Especially when you're trying to half-train a classfull of ignorant savages like HS/college students who don't want to be there and don't care, anyway.
So you simply do not value telling the truth? Or what jurists call the "whole" truth, not just the generalities?
Making false statements about hazards is itself a hazard. Aka, "crying wolf". Exaggerating and lying about physical facts is not virtuous.
The essence of scientific truth is diagnosis. Dia=two, gnosis=know, to detect and distinguish critically. You convict the guilty and acquit the innocent. Acquitting the guilty or convicting the innocent are both wrong. Type I and Type II errors. "Erring on the side of caution" evidences intellectual weakness. The knife is dull, so we'll use it as a hammer instead.
Here I will agree wholeheartedly. Tell the little darlings whatever they need to hear to survive their government fantasyland education. When they have been utterly evacuated of any fondness for learning and academics, they will be awarded a diploma purporting achievements. But by the name of Dewey, they will not have a drop of acid in their hands, much less roiling in their begoggled faces.
What, just because you insist it's safe to drink gasoline and breathe carbon monoxide, you don't expect me to believe you about this either?
I'm shocked.
Ummmm... that *is* the recommended practice: adding acid to water.
*My* feelings aren't hurt a bit. I'm just sitting here laughing at you continuing to pretend you know anything at all about chemistry and expecting people to take you seriously after some of the howlers you've posted -- and laughing even more watching you get your panties in a wad when someone catches you.
Your insults are just foolishness, because you're wrong. Physically, testably, and with scientific certainty, wrong. That you are smugly self- entertained by your own ignorant mocking of my prowess in this trivial tidbit of information shows your shriveled, boorish character for what it is.
It's as easy as pouring some water into hydrochloric acid. I'll happily stake my intellectual reputation on it. Be a hero and perform the experiment: this is your chance to earn your bragging rights instead of clutching the skirt of conventional wisdom, and forever after you can rightly kick me down the Usenet alley. Or are you the coward it seems?
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