# Calculate Electro-Etching Parameters

Disclaimer: The following calculations are based on Faraday's Laws and apply to perfect conditions. However, these calculations are still very useful for estimating parameters such as Average Depth and amount of Material Removed.

These parameters are:

Metal
These calculations are based on the pure metal. However, the numbers for alloys, such as sterling silver, brass, etc., should not be significantly different from the pure metals for small samples such as jewelry.
Area
The actual area being etched, not the size of the whole piece.
Amps
These calculations depend on a constant current power source being used
Time
An accurate time is required.
Current Density
The current density (amps / area) is a very useful number for repeating the texture of an etched area. Commonly the texture of the etched area is smoother with a low current density and becomes rougher with a high current density.
Average Depth
The key work here is average. It is nearly impossible to get a perfectly even etch.
Material Removed
The weight of material removed from the anode and either deposited on the cathode, precipitated out into the tank, or remaining in solution.

## Calculate Current Density and Depth from a Previous Etching

• Metal - The metal that was etched.
Copper  Silver  Iron  Aluminum
• Area - The size of the actual area to be etched, not the size of the whole anode.
square inches        (or square cm)
• Amps - The amperage setting on the constant current power supply.

• Time - The length of the active etching in minutes.
minutes

## Calculate Amps and Time for a Proposed Etching

• Metal - The metal to be electro-etched.
Copper  Silver  Iron
• Area - The size of the actual area to be etched, not the size of the whole anode.
square inches        (or square cm)
• Current Density - The amps divided by the actual area of the etch.
amps per square inch        (or square cm)
• Average Depth - The average depth of the etched area in millimeters.
mm 