Here is a bit of physics that I am struggling with:

I am using an electro-etching process which produces hydrogen gas. It
is produced on the cathode and comes out of the electrolyte as copious
bubbles. There is *no* gas produced on the anode. Yet the bubbles seem
to punch holes in the resist on the anode. I have done this enough
times to convince myself that these bubbles are the cause of
"foul-biting".

I understand about cavitation in general but always thought about it
as a process associated with changes of pressure within the liquid.
Bubbles develop in the low pressure areas of flow e.g. on propellers
and foils that collapse with considerable forces being generated in a
form of small water jets. Similar situation exists when the liquid is
boiling. I am wondering if introduction of gas into the liquid by
electrolysis makes the gas bubbles behave in the same way.

In practical terms I suspect the solution will be repositioning the
electrodes (I have the anode suspended above the cathode which means
that the bubbles pass over the surface of the anode before being
expelled from the electrolyte) but I would like to know if cavitation
is a reasonable explanation in this case.

Michael Koblic,
Campbell River, BC