Our Patinas

3 oz. (85 grams) Cupric chloride
½ oz. (15 grams) Ammonium chloride
1 pint (approx. ½ liter) Water

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Add the chemicals to the water and stir with a nonreactive implement. Brush or sponge the patina all over the metal's surface, leaving it puddled all over the piece. Allow to dry several hours or overnight. Reapply gently, so as not to disturb the first layer, which will be powdery. Reapply at least one more time. Rinse surface gently.

Ronald D. Young gives this patina in his book, Contemporary Patination (pp 69-70), where he recommends different application techniques than ours, and suggests ways of getting many different color variations.

approx. 50 grams Sulphurated potash (Liver of sulphur)
1 liter water

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The amount of potash can be varied in a very wide range to produce different densities of black. Grind the potash in a mortar, add it to the water, and stir with a nonreactive rod until the chemical is totally dissolved. This patina is much-used on bronze sculpture, but we currently use this patina only over a layer of blue-green. In good ventilation, and wearing a face-mask, heat the metal with a torch until the solution—brushed on with a soft brush—steams off instantly. Take care not to burn the surface of the blue-green while applying the second layer.

Our Dark Green patina, from which this formula comes, is Hughes and Rowe's number 5.117 (p 296). It is a traditional patina, and is found many other places as well.

200 grams Cupric nitrate
1 liter water

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Grind the cupric nitrate in a mortar, add it to the water, and stir with a nonreactive rod until the chemical is totally dissolved. In good ventilation, and wearing a face-mask, heat the metal with a torch until the solution—brushed on with a soft brush—steams off instantly, and leaves the color solid and dry on the surface. If the metal is overheated, the brush will stick and burn. If the color on the surface is accidentally burnt black with the torch, the patina may be simply reapplied to that area with good results.

This is patina 5.116 in Hughes and Rowe (p 296). It is the least toxic, and one of the easiest to use, of the many patinas which produce similar colors.

30 grams Ferric nitrate
1 liter water

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Add the ferric nitrate to the water and stir with a nonreactive rod until the chemical is totally dissolved. In good ventilation, and wearing a face-mask, heat the metal with a torch until the solution—brushed on with a soft brush—steams off instantly. The patina is very transparent, and must be built up slowly.

This is based on patina 5.51 in Hughes and Rowe (p 280), but our formula (above) is three times the strength given there, for quicker application.

50g Ammonium Chloride
50g Sodium Chloride (salt)
150ml Ammonia
3 liters water

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Add the ammonia and other ingredients to the water and stir until dissolved. Out of doors and out of reach of children, soak sawdust or wood chips with the liquid and bury the piece to be patinaed in the wood chips, and wet it down with more of the patina. Cover to slow evaporation. Check once or twice a day to see how the patina is developing; keep putting on more wood chips and/or patina liquid to fill gaps. We find that the patina only develops well on the upper surface where the chips and liquid are resting, so you will need to rotate the piece once its top is done to get each side in turn. Usually it takes two to three days to develop a good patina on brass, if you are assiduous in tending it and filling gaps.

Once the color has achieved good coverage, let the piece dry out in the sun for a few hours, then wearing a mask and gloves brush off the wood chips, back into the pile for reuse. You may then go over the surface lightly with a scouring pad to take away some of the powdery residue, if you wish. Either before or after brushing it, you can burn the patina with a torch. This should be done under a fume hood and with eye and breathing protection.

This is based on patina 5.164 in Hughes and Rowe (p 280), but our formula is a stronger variant we adopted based on a mistaken formulation of the patina by our friend, the sculptor Martin Metal.

approx. 1 Tbsp borax
approx. ½ cup water

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· borax is available in supermarkets and hardware stores, near the laundry detergent
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For use on Copper only. Extra safety precautions are necessary because of the high heat involved: you must place your copper on real firebricks, and keep flammables well away from the flames and the hot metal. Note that in air it will take copper, even thin copper, a long time to cool from 800°F or higher to the point where it can be handled. For any but very small pieces of copper, you will need a strong heat source such as oxyacetylene. You should also be able to do this in a kiln.

Amounts are extremely approximate. Mix some borax into water to make a thin solution. Brush onto surface of copper. Heat copper until it glows anywhere from a dull red to bright orange. Let cool or quench in water.

This is a classic heat effect patina. Copper which is heated to glowing with no surface treatement, and allowed to cool in air, will develop beautiful, intricate brown colors. Often the back side of a sheet will develop some reds and blacks, sometimes quite beautiful ones. The borax fuses to an exceedingly thin layer of glass on the surface, and keeps the air off it while it cools, allowing more of the red and orange colors to remain. You will find that this is not very controllable, but the results range from interesting, to striking and beautiful. If you don't like the results the first time, try reheating. You can add more borax solution if you like. It is also possible to brush the borax on once the metal is slightly warm (not hot or you will burn your brush bristles) - this allows slightly more control of the brushstrokes since the water will evaporate as you brush, and therefore will not start travelling about as you bring up the heat.

This is a very widely known patina, which many people use. You can get similar effects with related liquid fluxes, such as Cupronil, but you want to make sure you're not using a toxic one. Liquid fluxes like this let you get a more even coating, especially if you spray it on, and especially if you spray it onto warm metal. (Do not use modern 'self-pickling' flux liquids, as these defeat the purpose.) Be sure as always to wear breathing protection if you spray chemicals.

approx. ½ tsp. silver nitrate
approx. 1 cup water (250ml)

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This is a very easy patina to use - it sticks and reacts well on brass. You should wear long sleeves and gloves in addition to ordinary eye and face protection when applying it, since splatters from the the hot patina actively and semi-permanently discolor skin and fingernails.

Stir flakes or powder of silver nitrate into water. It should dissolve easily. Apply while heating the metal till the water steams off as the patina is brushed on. Patterns can be made with brushstrokes and puddling, but note that much of the effect of these patterns comes from a powdery surface layer, which can be smeared or rinsed away. If you wish to keep the grey and white effects as they stand when the surface is first cooled, use a spray fixative. Otherwise, rinse the surface, wearing rubber gloves to keep the residue off your hands. Once it is rinsed and completely dry, it can be waxed. Once the wax is dry, the surface can be buffed to produce a shiny silver or silver-grey color, sometimes dramatically different from the unbuffed look.

Our silver patina was suggested by a fellow craftsperson, but similar formulas can be found many places, including Ron Young's book on page 54.

Part 1:
125g Cupric Nitrate
85g Cobalt Nitrate
4 litres water

Part 2:
250g Cupric Nitrate
4 litres water

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Many sculptors spray most or all of their torch-technique patinas, but this is the only one we normally spray instead of brushing, because of the particular effects and patterns possible with spray in this case.

Mix the two parts equally in a spray bottle. The instructions in the Bryant Lab handout stipulate that parts 1 and 2 of this be mixed separately and only combined when ready for use. We follow this advice, but given how long we have left the parts mixed together in our spray bottle with no perceptible effect, it may be perfectly okay to store them mixed into one container. (Part 1 is worth mixing on its own, though, because of its beautiful amethyst color!)

The techinque for application is similar to brushed torch technique patinas: heat the surface to the point where the liquid will steam off instantly as the patina hits it. Given the extra splashing of the spray as it hits hot metal, it is essential not only to protect the eyes, but also to take precautions to protect face, arms, and hands from the splash of hot, reactive patina. In addition, a heavy, chemical-resistant rubber glove is important on the hand holding the spray bottle, since all spray bottles leak.

We make three different patinas based on this one. If you use a wide, gentle spray of fine droplets from you spray bottle, you can produce a very even color we call Robin's Egg Blue. If you use a jet which splashes into one spot, you will get interesting patterning in the color.

The trick to getting the extreme patterning we call Turkish Stone is to spray an even coat (with torch technique), then go over that finished patina with the torch alone to burn it black, being careful not to burn it so severely that the patina begins to peel from the surface, then crank the spray bottle to a jet and go over the black surface again with the torch technique, creating a pattern of overlapping spots and rings. Our Stone Grey patina takes this one step farther by adding silver patina (above) over the top of the Turkish Stone. We discovered the Stone Grey effect ourselves, though others have done it before, and there seems to be a version of it done with Gold Nitrate as well.

1 heaping tbsp bismuth nitrate
1 heaping tbsp titanium dioxide
1 heaping tbsp stannic oxide
approx. 1 liter water
(optional: several drops of sodium silicate)

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In the concentration we mix this patina, it is mostly useful only for a transparent layer on top of other patinas. In any case, it does not stick and react strongly with bare brass. If you add the sodium silicate, the patina will stick much better, and very little if any will rinse off, at least when applied over other patinas. If you do not include the sodium silicate, rinse the patinaed object well under running water and rub it with a cloth or a rubber-gloved hand to remove the excess, or it will smear badly when you seal the patina with wax. Experiment with different concentrations, keeping the main three ingredients in equal proportions.

This formula was given to us by a fellow sculptor, Cheryl Barnett, but it closely follows a recipe given by Ron Young on page 55.