Buon Giorno, Davide!
(that's pretty much the extent of my Italian other than "ciao!" and
"grazie" and "no capisco")
You ask a good (and logical) question. Perhaps the best way to
answer it is to ensure that you understand what the patination
process is doing.
Patination is the process of creating an oxidation layer in the
metal that changes the refraction of light hitting the metal. That
oxidation layer can form in many different ways and at many different
When you expose copper to the sawdust patina, you wait until the
oxides form to the level you wish, then wash the piece thoroughly in
soap and water. This removes any residual traces of the ammonia or
ammonium salts, but leaves the oxide layer to provide the color.
You can also do fume patinas, where the metal is in a sealed
environment (like a lidded jar or zip-loc bag) suspended over the
ammonia for a period of time. The fumes cause a layer of oxidation to
build very evenly over the surface of the metal. In this case, you
still wash the metal afterward, but there's never been any contact
with the liquid ammonia.
Patinas can be delicate and can scratch or abrade. Many can be
sealed with lacquer (I'm really liking Rio's "Midas" finish lacquer
for this currently) or a mixture of turpentine and beeswax. The
darker patinas, as well as the golden/chocolate colors work very well
this way. The iridescent patinas (on silver) don't seal as well,
because they depend on the refraction of interference colors; I'm
working on researching some options for sealing them, but have
nothing definitive to report yet.
Your best bet when working with patinas, though, is to design around
the fact that you're using them. Create recessed or protected areas
where they can be worn without abrading or contacting the skin (which
will darken them via skin oils and help them wear away and dull
Hope this helps!
No Limitations Designs
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