Nickel Plating and Blistering Defect Reduction

Really need to know the substrate to properly determine cause of blistering. I do not know what you mean by sulphurless nickle plating.

Blistering and poor adhesion typically result from improper cleaning. If the pH of the bath is out of range, too much brightener, or contamination from chrome or nitrates these can also contribute. Parts should have been acidified/activated before putting into nickel bath.

If the 'blisters' are really laminations of nickel deposits, this can result from interrupted current (power interruptions) incompletely stripping before replating, or too much iron in the bath.

If you are doing nickel plate over copper, if the copper got stained or tarnished during rinse before plating that could also be a cause.

Streaky deposits or dark streaks are signs of chrome or nitrate contamination in the bath; evidence of which I mentioned in para #2 above.

milo