Interpreting Zinc Plated Hull Cell Panels

This is one in a series of four videos on Hull Cell Testing. To view the complete series, click here.

Video Transcript:

Zinc Plated Hull Cell Panel

Zinc plating baths of all types, alkaline or acid demonstrate similar characteristics when evaluated using a hull cell. First, it is important to consider the reference hull cell which demonstrates the characteristics of the bath when operating at its full potential under stable conditions. All of the hull cell panels used in this presentation are 2 amp, 5 minute panels. Different types of plating baths may be run under different conditions. You should consult your supplier for specific instructions.

Notice the reference panel demonstrates full brightness across the range of current densities. There is no burning, there are no clouds, the deposit is fully bright. There is no roughness or other indication of impurities in the bath. Obtaining a hull cell panel similar to the reference panel is the goal of this analysis. It is always a good idea to compare the work coming off of the line to the reference panel. This provides a chance for a better understanding of the role of the hull cell analysis.

Running the Hull Cell Panel

Begin the analysis by taking a sample of the zinc plating bath. When taking the sample, is important to evaluate the quality of the work coming off of the line. Using the sample which has been taken, run a zinc hull panel at the correct amperage and time. It is important that the temperature is similar to that in the operating plating bath. After the panel is completed, it is appropriate to process the panel in a bright dip of very dilute nitric acid. Reference for assistance may be made by reviewing the first video in this series.


This panel indicates the presence of a condition known as “burning.” Notice the dull white deposit in the area of the burn.

The most common causes of burning are:

  • Low operating temperature
  • Low concentrations of the plating salts
  • Additive agent imbalance


This panel shows evidence of dullness or a cloud. Notice the dull hazy appearance.

The leading causes of dullness or cloudiness in a zinc plating bath solution are:

  • Imbalance of addition agents
  • Imbalance of plating salts
  • Buildup of organic impurities

Impurities Present in the Bath

This panel represents the presence of metallic impurities in the zinc plating bath. Notice the dark deposits. Metallic impurities typically appear only after the panel is dipped in the dilute nitric acid solution following plating in the hull cell. The dark area is typically present in the mid to low current density area.

This video is intended to provide guidance and is for illustrative purposes only. It is not intended as a comprehensive discussion of hull cell testing or interpretation of zinc plating bath hull cell panels. Nor is this presentation intended to substitute for the recommendations of a trained metal finishing professional. The conclusions of any hull cell testing are those of the operator and care should be taken prior to the making of any changes to a working plating bath solution.

For additional information, to obtain a copy of the Asterion Trouble Shooting Guide for Zinc Plating, or to arrange for a technical consultation, please contact Asterion at 1-800-428-0719, or visit our website.