artificially ageing objects?

Answer 1

The techniques will vary with the object to be "aged".

Some art work, including paintings use light.

Rubber and other organic materials are often subjected to heat and ozone gas.

Paper products have been treated with dilute acids to simulate "age."

Silver objects, including pewter, are subjected to sulfur containing compounds to blacken them.

Wood items can be beaten and buried.

Answer 2

I understand that some sellers of phoney antiques do a good job by just burying it in the back yard for a few weeks or months and let whatever is in the soil age the furniture/object/document. No personal experience. I, personally, would like to be a little less aged.