While searching the web for larger quantities of blacken-it I found this little tid-bit on ageing brass. Very interesting.

Ammonia Fuming
When brass is exposed to an atmosphere of ammonia vapor it develops a green brown oxide finish. This oxide layer is as close as you can come to a natural patina.

The following instructions will allow you to patina smaller items with relative ease, the same principals can be adapted for larger pieces.

You will need a plastic container with a tight lid. We use the white buckets sometimes called "Pickle buckets" that can easily be obtained from hardware stores, breweries and many other sources, any other well sealed plastic container will work. Cut a piece of plywood to make a shelf that will sit a few inches off the bottom. This shelf can sit on three blocks of wood to ensure it remains level. Pour a cup of full strength or "Clear Ammonia" into the bottom of the bucket, place the items for antiquing on the plywood and snap the lid in place. Full strength ammonia can be obtained from architecture offices or print shops with "blueline" facilities, "Clear Ammonia" from the grocery store. It is an extremely unpleasant fluid and should only be handled by competent adults in well ventilated areas or outside.

Depending on the temperature, humidity and freshness of your ammonia the antiquing will take minutes or hours so take the occasional look to see how it is progressing. The color will darken a little and inclusions of verdi-gris will form when the items are removed from the container. You can either leave the finish as is or wax it for a burnished effect.

If you are seriously attempting to fool anyone as to the age of the hardware and furniture you will need to mount the antiqued fitting, then wax and polish it in place. If done with some general understanding of the effects of care and aging on actual antiques the results can be very convincing.

Because the ammonia evaporates fairly quickly leaving only water you will need to replenish or replace it every so often.

Great Tip!!!!!!!

OT.... OOOOHHHHHHH Blueprint Ammonia haven't had that Pleasnt smell in awhile....... Thank You large format Digital scanners!!!!!!