http://davidmbowman.com/patinas/patinas.htm

Looking Forward Looking Backhttp://vintajia.blogspot.com.br/2012_01_01_archive.html

It has been really hot here for the last 2 weeks and creativity tends to wilt in proportion to the rise in temperature. So most afternoon we have taken our deckchairs down to our rainforest lined creek, and sat in the shade with our legs in the cool water waiting for a breeze. The time was also used to review the passed year and the direction of the future.My year was one of endurance and frustration as events beyond my control moved at glacial pace. These events have finally been resolved. One more hurdle to get over and onwards.The silver lining of this cloud has been the time I have been able to devote to being creative - just playing.Most of the playing involved enamel so thought I'd share some of my enamel tests and the direction my inner 'mad professor'

wanted to take.I have flirted with pretty enamel, but I was looking for rustic, grungy, raw and edgy. So began the journey.

This is a series using liquid white enamel and liquid copper. Was hoping to get copper nitrate, but the local pharmacist's eyes glazed over when I tried to order some.  Lateral thinking and a trip to the hardware store yielded cupric hydroxide a gardener's fungal treatment.(Note: copper nitrate and copper hydroxide can be a hazard, so sensible precautions to limit exposure are required)Tile one was wet on wet. Tile 2 is wet on dry liquid enamel. Tile 3 is strong copper

solution on wet white liquid enamel and the last is the same as 3 but high fired. The wet on wet yields a rather nice dotted halo effect. Best results are using a weak solution.Put this one in the useful file.

This is a test using borax which is a flux. Like the pink effect where the flux has thinned the enamel and let the copper show.2nd panel was fluxed and high fired.The third one is the craters left when the borax is quickly heated. Might be more effective on paler colours. (Note: borax is also hazardous) 

Next was a test of white liquid enamel with a reduced atmosphere flame. The 2nd one had flux added and the last one was fired from the front deep in the flame. Really like speckled carbon deposits and the colour variation where the flux ran

 Next some more of my faves - toxic chemicals! This time in the form of salt glazing. Salt glazing in pottery gives a textured satin finish so thought I'd try. (Note: heating the salt results in the release of chlorine gas soooo beware)Love love LOVE the result on this tile.Satin finish, great colours, fine texture and detail,but could I duplicate it?

 Nope, nope, nope, and nope! More time and testing needed on this one. 

These two are a combination of liquid enamel, cupric hydroxide and borax. The bottom one is high fired. Really complex textures and colours. Put this one in the useful file.

Copper Red Patinas – More  IdeasA red patina can be developed on copper with a torch and any number of fluxes. The heat is

applied to the copper from below. When the copper glows red hot sprinkle on the flux for a speckled look. Alternately, apply the flux first, then apply heat, for a smoother color. (Generally, both techniques happen at the same time because the salt bounces around.)(If you don’t apply the flux you can get lovely tans and browns to blacks, depending on how hot you heat the metal: red hot gives the darkest colors.)

Rosebud TipBe careful with this technique, especially with thin copper. It is very easy to blow a hole through the red hot metal.Note that a black crust forms as you work the metal. You can’t see what is happening underneath! Thus every patina is different and a surprise. You can’t see what it looks like until you cool the metal down and wash off the crust.Also, if you reheat an area that you’ve previously salted, the colors change, often going to oranges.I use a rosebud tip on my oxy-acetylene setup (see image right). You can buy one of these at your welding supply store, or on-line, for about $55. This create a very hot wide flame and helps get the job done faster. Be careful not to touch the gas controls while using the redbud tip – I hold it behind the control knobs.

Copper Red Patina with Sodium Chloride (table salt)Note: you have to turn the oxygen and acetylene dials way up to the 5-10 range. Start with the acetylene plus a little bit of oxygen to minimize the soot floating around the room. Get the torch going, then dial in the oxygen until the yellow flame is about an inch long. Don’t go to a flat blue flame! Heating the copper releases bonded oxygen. This oxygen super-ignites the flame, creating a very loud pop and blowing out your flame. Startling! When you turn the torch off, turn off the acetylene first to avoid the loud pop. The pop sounds like a gun blast heard from a distance.Other aspects of this technique -  I support the copper on bricks (on concrete blocks standing on a board laid over sawhorses) at a height a few inches above my elbow height to avoid arm strain. The copper invariably warps and bends with the heat. I wear the thickest & longest welding gloves I can find and touch the metal as little as possible when moving it. A large spatula-like tool can help with the repositioning. I do this procedure in the garage door: not actually outside to avoid wind gusts; not inside to avoid fumes and heat and soot. Carefully sweep up the spilled salt afterwards. All salts are deliquescent (moisture attracting) and corrode concrete.

Copper Red Patina with Ammonium Chloride (sal ammoniac)In theory, you could heat the copper very uniformly with multiple gas jets while holding it flat on a grill. That might allow more control.For metal, I generally use 99.9% pure copper, such as roofing copper, .015 to .030 thickness. The .015 copper takes a gentle touch: don’t hold the flame too close. I used .015 copper scrap for these experiments.Note that all the colors formed are copper oxides: copper (I) oxide, Cu2O, a red color; copper (II) oxide, CuO, a black color. Thinner layers of Cu2O appear as orange to brighter red to pink to purples; thinner layers of CuO appear as tans to browns to dark browns.Copper Red Patinas – Experiments

The photo at the top shows the four experiments I conducted as a group. (Note that these samples are unlacquered. All colors appear stronger, deeper and more vibrant after being lacquered.)  In my previous article on creating a copper red patina, I stated I was using table salt

mixed with baking soda (sodium chloride with sodium bicarbonate) in a 5:1 ratio. I started doing this to get the red to adhere more to the copper. That was successful, but at the cost of the loss of many of the lighter oranges and browns. Some people liked it and some didn’t. It tended to give mostly reds and blacks, with just a few oranges. I felt like I needed to get back to basics.

Copper Red Patina with Calcium ChlorideExperiment 1: NaCl, sodium chloride, aka table salt. This was the flux I started off using, many years ago. Note that the hotter you get the metal, i.e. bright red hot, the less red patina that will adhere, because hot flux aggressively cleans the metal. Black areas are places that got red hot but did not get fluxed. If you can achieve a dull red color, then sprinkle on the salt, interesting effects can be achieved.Experiment 2: NH4Cl, ammonium chloride, aka sal ammoniac. This is a flux used by stained glass window artists. It also has some applications in cooking: see the Wikipedia article. This was an incredibly unpleasant flux to use. Fortunately I was working in the open garage door and could avoid most of the fumes: it took a day for my lungs to recover. Note the beautiful yellow-green patina that formed. Yellow-green patina is a clear indication of copper chloride. This patina could be left on or scrubbed off.

Copper Red Patina with Potassium ChlorideExperiment 3: CaCl2, calcium chloride, aka ice-melting salt. Not bad, interesting. Note the blue crystals that formed. Fairly straight forward application. Has promise.Experiment 4: KCl, potassium chloride, aka Salt Substitute. I used Morton’s Salt Substitute because it had the least amount of additives and no mineral oil. This gives a lighter patina than the table salt, with a lot more oranges. My favorite for this group. Also easy to use.Other possible fluxes: zinc chloride, widely used in fluxes for soldering; borax – gives a beautiful red but the borax forms a glossy glass-like covering that takes work to remove; baking soda – reds but hard to remove; phosphoric acid (haven’t tried it); here’s a list of many more.In general, fluxes do two things: clean the metal and block out oxygen.Copper Red Patinas – Afterwork

Copper Red Patina with Potassium Chloride1st, cool the metal. I spray the backside with water from the hose.2nd, rinse off the black crust and the flux from the front. You will lose some red at this point so don’t rinse for more than 10 seconds or so. You will do more rinsing later.3rd drip dry briefly as you carry it to a table4th, gently flatten the metal with a piece of wood. You don’t need it super-flat, you just want it flat enough to dry without having large puddles. Drip dry briefly again as you carry it to its drying table.5th, lay flat to finish completely drying (not in sun). If you dry it leaning, it will develop streaks. You might like that. The sunlight heats the metal to much, which dulls the colors.6th, when completely dry, lay several damp towels over the metal to soften any additional flux. After 4-6 hours or overnight, remove towels and rinse off any remaining flux or white powder.7th, Dry completely again.At this point you could hammer it flat, glue to a substrate, lacquer, make jewelry, etc. I have found these patinas to last for many years inside, but outside, without lacquer, they turn brown and lose their vitality.Favorite lacquers: Clear Guard (fast-drying, great adhesion, satin) or Incralac (slow drying, high gloss, excellent adhesion). I’ve heard good reports regarding Permalac and Nikolas #8321 lacquer. Avoid any nitrocellulose lacquers or water-based lacquers. Krylon clear works fine inside, degrades outside in a few years.Copper Red Patinas – Additional Ideas1. if you like most of the patina but not all, lay a wet towel around the area you want to keep and work on the area that needs work2. Use different fluxes on different areas of your metal3. Add some green acid patina to the red – the red and green patinas work well together4. Melt brass or bronze on the metal before doing the patina