What is the life span of the chemical bath?

As with working with any chemical, it’s important to dispose of any used chemical safely and in compliance with all local laws and regulations. The life span of the chemical bath for etching is ultimately dependent on the amount of etching you do. Over time as metal is deposited into the solution, it will gradually lose its strength. Fresh chemical can be added to compensate for this. Typically, you can expect to have to change the solution entirely every six to 12 months. As a good rule of thumb, you can expect to pay roughly the same to get your used chemical taken away as it cost to buy initially. 

   —Masteretch Services