TO PATINA OR NOT TO PATINA
Why won't the black patina go black? Why is the copper all blotchy and dirty looking? Why does the glass have a halo or etched look next to the foil lines? Why are my fingers all smelly and brown? (Well, maybe we'll get a hygienist in for that one)
Black, copper or silver? Choices that need to be made, and often prior to beginning the foiling process (so that the suitable coloured foil can be used on transparent glass, but that's a topic for another day). Often the look of unsullied shiny solder lines looks impressive to beginners, but silver lines overcome the glass and distract the eye. Try it yourself- take a small piece without patina and place it alongside a similar one with patina, and see the difference it can make. One draws attention to the solder line, the other more appropriately, to the glass
The only way patina will work is if the piece is absolutely clean. This doesn't just mean cleaning the flux off, it also means removing any oxidation (corrosion, rust, etc) that might have built up, which is apt to happen if flux stays on metal for any length of time.
Fluxes have become increasingly exotic over the years and for this reason, special cleaners have been developed to cut through these liquids. Detergents such as Neutra 5000 from Gauthier and Neutraline from Legend are such cleaners that not only remove all residues, but because they are alkaline also help neutralize the acidity of the flux. Other adequate cleaners are dish soap, ammonia, and whiting which is an absorbent, abrasive powder also used in cleaning leaded panels.
After the piece has been washed, rinse with lots of clean water to flush away all residues.
The effectiveness of black patina can vary greatly according to manufacturer, so it is wise to experiment here. They all contain acid, and are corrosive (that's why they work) and for this reason it's a good idea to wear some gloves. The trick to black patina is speed. Because of its higher acidity, to avoid your glass from being acid- etched, you want to get it on and off as quickly as possible.
Pour some patina into a nonmetallic cup, and using a rag or paper towel dip into the patina and wipe all over the lamp, solder, glass, cap and all. Once the entire piece's solder has turned colour, rinse it well under clean water, to dilute and remove any remaining patina.
Copper is much more problematic than black. The same basic principles apply. Namely, the piece must be absolutely clean and dry and free of any oxidation.
Again, pour off some patina into a nonmetallic cup, which will then be discarded after, not repoured into the original bottle (impurities and electrolytes are added and lost, reducing their effectiveness). This patina is then applied as black patina, covering all the solder. You can go over the piece several times increasing the depth of the copper colouring. Once finished, do not rinse with water. Impurities, etc in the tap water will react with the still active patina, staining it, creating dull and grey spots ruining the copper finish. The secret here is to wipe the piece dry with clean paper/cloth towels (Holiday Inn pool towels work quite well).
As with all good things, oxidation (rust, aging, etc) will always set in. The trick is in not stopping it, but in slowing it down (sorta like why we eat our spinach). The application of a good wax, be it furniture or car wax, or our favourite, Kempro Finishing Compound, will add a shine to black patina, a bright and even finish to copper patina, and enhance the beauty of your work. As for those brown fingers, sorry, we've run outta space...