Causes for this can be an imbalance in stabilizers or accelerators in an electroless nickel bath.

Rust of steel or attack of the base material due to improper storage of parts prior to plating or during the plating cycle can create these issues.

Excessive stabilizer levels in an electroless nickel bath can cause edge pull back which is low plating thickness on an or no plating at all on an edge.

Accelerator levels outside of the optimum level can cause variation in the appearance of the plate.

Maintaining the electroless nickel chemistry within the optimal operating parameters prevents these problems from occurring.Proper control of the electroless nickel bath and choosing the proper pre-treatment prevent this from occuring.