What are the precautions for using black zinc sealant?

When using black zinc sealant, it is essential to strictly control process parameters and operating procedures to ensure a uniform coating appearance, consistent blackness, and stable corrosion resistance, while also safeguarding production safety.
Workpiece Pre‑treatment: The workpiece must first undergo galvanizing, degreasing, descaling, activation, and black passivation, ensuring a clean surface free of oil, water stains, and adhering scale. After passivation, the part must be thoroughly rinsed with clean water to prevent residual acid or alkaline solutions from entering the sealing bath, which could cause the sealing solution to age and develop discoloration or spotting.
The bath solution must be prepared according to the specified concentration ratios in the manual; do not arbitrarily increase or decrease the concentration. Maintain proper temperature, processing time, and agitation/spraying conditions—excessively high temperatures can cause peeling and bluing, while excessively low temperatures result in insufficient blackness and poor corrosion resistance. Regularly monitor bath‑solution parameters and replenish the sealing agent as needed.
During the impregnation, spraying, or ultrasonic sealing processes, ensure complete wetting of the workpiece surface and eliminate air bubbles in crevices and holes. After removal, allow excess bath liquid to drain thoroughly to prevent streaks and watermarks. Adhere to the specified curing temperature and time to achieve a dense, well‑adhered coating.
Post‑processing requires enclosed drying and curing according to the specified process; avoid air‑drying, as this can lead to blooming, dust adhesion, and reduced corrosion resistance. After drying, allow the parts to cool to room temperature before packaging and stacking to prevent scratching and sticking.
Safety and storage: Sealants are typically chemical products; wear acid- and alkali-resistant gloves and safety goggles during handling to avoid contact with skin and eyes. Do not allow the bath solution to come into contact with other chemicals. Store the product in a sealed container in a cool, well-ventilated area, away from sources of ignition, high temperatures, and strong acids or bases, to prevent degradation and potential safety hazards.