Following characteristics are required for electrolytes for electrolytic machining.

There are electrolytes that generate precipitation while others do not. The former includes neutral salt solution such as NaCL, and the latter includes solutions of various acids and alkali.

(1) Neutral salt solutions

Neutral salt solutions are in common use since they are less corrosive than others, though have lower electrical conductivity. As anode reaction, compounds of metal and negative ions are formed, and as cathode reaction, hydrogen gas and hydroxyl ions are formed. These byproducts make chemical bounds with each other in the solution to form insoluble hydroxides.

The hydroxides will float in a colloid-like form in the electrolyte, and do not largely affect the electrolyte's conductivity, process speed, finish roughness, and accuracy up to 2wt% (weight percentage) of concentration. If the concentration value exceeds the above, the liquid's viscosity will sharply rise and inhibit the electrolyte from flowing freely. The concentration must be kept below 2wt%.

Typically, removal of precipitated byproducts is performed by combinations of filtration, centrifugal separation, and sedimentation. It is more economical to clean and reclaim even the lowest cost electrolytes (such as NaCL) rather than disposing and replacing.

Most popular neutral salt based electrolyte is the NaCL solution. It is used for almost all metals including steel alloys and nickel-chrome alloys.

This solution contains chloride ions that inhibit passivation of anodes, and since Na ions are the positive ions that do not electro-deposit on cathodes. These characters make for excellent as electrolyte solution but it is somewhat corrosive and has low machining accuracy as shortcomings also.

The reason for the low machining accuracy of the NaCL solution is because of the solution's high throwing power. The "throwing power" is the ability of an electroplating solution to deposit metal uniformly. Since "high throwing power" means good metal elution even when the gap is large, the machining accuracy would be lower as the result.

Electrolytes such as NaCLO3 and NaNO3 are used as low throwing power types. These are non-corrosive and have good machining accuracies, but with low electrical current efficiencies.