Many people beleive that you need special chemicals to black brass or that you need to tin it with solder first!
NOT SO!!
In the picture on the right ordinary blacking solution as you would use on solder has stained a brass vase cap.
If you try hard enough you might get it black but chances are it will be blotchy.
The secret is to use a Scotchbrite green scourer (or similar as here!) and give the vase cap a good going over first to remove any oxides or varnish.
Then apply the blacking whilst rubbing with the same scourer. It's a doddle!
Exhibit one on the right! (By a miracle of modern science it appears blue here!)
Getting a uniform colour is just an easily aquired knack. You can apply wax (if you must) and buff it up for a really finished look!
Some people add salt to blacking solution but I always find it tends to fall off.
I find that this is a far more durable finish.
I have no idea about the chemistry involved but I use exactly the same solution and technique for zinc as well!
