SuttaCentral
I have a Buddha and Samantabhadra statue in an altar space at my home.
For years I have struggled to keep these from tarnishing. I assume the material is some kind of bronze alloy as they are quite heavy. One tarnishes more easily and with a darker tone than the other.
Is there an acceptable technique for cleaning and polishing them?
Thank you.
I’m going to go on a limp from handling instruments extensively, I assume most basics should apply.
Assuming it is indeed bronze, a little bit of water should be fine (ideally, distilled or at least boiled & cooled water). Basic kitchen soap should be more than fine to clean any real dirt. Assuming you don’t want them to get scratched, wiping with soft cotton towels ot cotton pads should do the trick
If you want to give it a polish, something natural like beeswax should do wonders. Applying a thin layer, then buffing it with a soft cloth.
To remove the tarnish, a simple lemon juice & baking soda mix should do the trick. But doing this too often or letting bronze exposed to the solution too long might be damaging in the long term. I’d suggest first cleaning it with soap anyways, to see if you think it still needs a proper clean up. If you do go with this, save the waxing for after this clean up.
There’s abrasive cleaners and/or more sophisticated polishing materials, but they can remove the natural patina, which you may or may not want to keep. I personally liked my instruments with their natural patina so I can’t give a too detailed ideas on such chemicals. 
I’m not sure about bronze / alloy, … but I worked p/t in a jewellery store in my uni days, and always found it fairly shady that we were selling commercial jewellery cleaner to people out front and meanwhile, out the back, we were using tap water with a squirt of dishwashing liquid and a few drops of ammonia. Brought things up beautifully.
Whatever u try, I suggest maybe do a tiny test patch under the base before going at any of the visible parts.