How to patina copper (darken it)

A. Hi. We other readers don't know your artistic ability and craft experience; but kitchen ingredients are probably either for highly experienced artists or for very general work -- not for meticulous work and carefully examined articles like lamps.

The problem is that there are different copper grades, brass grades, manufacturing methods, heat treatment histories, etc., and it is difficult to predict exactly how the copper and other metal components will react with the vinegar & salt to produce various copper salts like copper acetate. It is usually better to buy a commercial patinating solution that sort of 'paints' on and which already contains the necessary copper and reaction ingredients to offer the finish you want.

One thing to recognize about the difference between the green and brown patinas is that the green is less abrasion resistant and durable. For example, you never see green pennies in circulation, only brown ones ... but if you find an old penny in the slats of a boardwalk where nothing has been rubbing it, it will be green. I also see green copper roofs where rubbing tree branches or a constant drip from the floor above generate brown areas. Luck & Regards,


Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

A. DOG URINE, AND I ASSUME, HUMAN URINE, MAKES IT A NICE LIGHT BLUEGREEN COLOR. MY DOG TAUGHT ME THAT.

A. 'Bunch of years since this inquiry left the gate, but here goes for current newbies like me: hydrochloric acid (as demonstrated on a design show).

A. I think the best product to use is Birchwood Casey antique black finishing gel.
It can be used at room temperature. Being a gel, you can use it on a flat surface or 3 dimensional shape,(no drips), and easy wash-off.
Nim

A. I find that Jax patina solutions →
work very well. They are available at many art stores as well. Liver of Sulphur works very well, you may want to use a fine scotch-brite pad to even out the surface. I use liver of sulphur daily and the method of application is mixing the solution, a thumbnail size to a pint of warm water. Let it dissolve and sit for about 30 minutes. Use the scotch-brite pad and rob the patina in in circular motions, blending the solution onto the copper panel. It will be easier to work with the pieces flat on a table. Liver of sulphur has a short reaction time and once it has reacted, the effects tend to die off quickly.

A. Hi, Tim. Probably the easiest source is Amazon.

Regards,

A. Hi, on a number of occasions I have had to turn large copper sculpture black and varying shades of brown as well. I use Birchwood Casey M-24 liquid solution. I will usually strip the original patina with Muriatic Acid or Soda blast it off. Both do a good job of etching the metal and providing a superior surface to reapply an even, adherent patina. I mix the solution with distilled water, 50/50 for browns, 100% for blacks. I spray it on with a HVLP sprayer at 20 psi and a 1.4-1.7 nozzle on the gun.

Heat the surface to an even temperature if possible using a patina torch 200 degrees TOPS! the more evenly heated the piece is the better patina you will get, trust me, take your time on this one it has been my experience that if you don't get the results you are looking for on the first 3-4 tries you will start to see areas of the finish peeling off. with a good even heat, spray, and proper prep work the finish will be a tough one to beat. If you get it too hot or reapply more than 4 times you will start to see a steely blue gray. That means it's time to strip it and start over, it only gets worse from there. Let each application stay on for 20 min or until the metal cools then rinse with plenty of water, if the metal is still hot the water will streak the finish.

Rinsing from the bottom up helps eliminate any chance of streaking. While rinsing I GENTLY run my hand over the surface to remove any powdery residue the water doesn't. If I like it, I thoroughly spray it with acetone and top coat it with Permalac (outdoor) or Butchers/Renaissance wax (indoor); if not, I dry it with compressed air and reheat/reapply. Hope this helps!

A. Hi guys!
Now everyone on this thread seems to be asking a similar question about getting copper to a darker patina. There are two that seem to be in vogue here, and while you can make something that approximates what you want with a patina, nothing really is going to look as good as time will give you. If you want it now, here are two methods to do green and brown patinas on copper.

1. Green patina.
Mix darkening solution of 2 parts white vinegar, 0.50 part non-iodized salt, and 1.5 parts of clear, detergent-free ammonia. Spray on the area you want to patina and reapply every 1-2 hours until you get the color you want. The patina will look powdery, leave it alone, it will eventually work in the copper and get to that more 'glazed' look. 72 hours or so from when you apply it you should have a better idea of what the final look is.


2. Brown patina.
You need to dissolve baking soda in boiling water until it won't dissolve any more. Spray on to the area to be patinated after the solution has cooled, and reapply every 2 hours or so. This one will reach more towards the color of an old penny.