This is normally caused by the solution in the etching machine losing it acidity. This can be checked from time to
time by taking 5‐10ml of solution and adding it to 50 times the amount of water in a clear jug or beaker.
The ferric should look a clear to green colour, however if it appears to be cloudy with
particles floating in it then add 1% by volume 36% Hydrochloric Acid. When carrying out this test always allow the Spray Etching machine to run for 3-4 minutes before carrying out the test.