While screwing around I decided to try something I've seen someplace. This is a piece of sandblasted bronze sprue sitting on top of a cup in a sealed container. In the bottom, is good old household ammonia. Pretty interesting and this is less than 24hrs! I'm curious to see how tough this coating is after a few days. Any thoughts from you expert patineurs?
I use it sometimes. It will come off at a touch. Don't try to wash it. To keep it intact it will have to be sprayed with a fixative of some kind. Richard
This is 1/3 the recipe for what known as "the kitchen cupboard" patina in some foundries (cos you can find the ingredients in the average kitchen cupboard). The other ingredients are white vinegar and salt. You can spray a fine mist of alternating ammonia and a mix of salt and vinegar. Or you can fume as you did. The ammonia gives you blues as you can see in your test and the salt and vinegar solution gives greens. Combined it can be a really beautiful patina but the final outcome is in the lap of the gods. Ive had really great results very fast but also had to rinse and scrub the piece over and over to get an effect im happy with. As rasper said, it needs to be fixed with a laquer (applying wax will rub it away) to keep it from turning to dust.
Yep, cupric is a lot more stable and you can get more consistent results than ammonia. If you combine it with ferric and liver (not in the same mix but as a layered patina) you can get a wide variety of finishes that are fixed. You may need some more advanced chemicals if you want that bright blue finish tho.
Does cupric nitrate have a shelf life? I keep my chunks of LoS in a glass jar and they have kept well over a year.
I have cupric nitrate I bought twenty years ago. It still works fine. I have used a cold process patina of cupric sulfate and ammonium chloride (if I remember correctly) to get a blue patina. It's very opaque though. Richard
I've been curious about patinas recently and after some googling came across this site ... https://www.sciencecompany.com/Patina-Formulas-for-Brass-Bronze-and-Copper.aspx It's now residing in my bookmarks. Thought you may be interested too.
