Here is a list of the problems that can occur during the galvanizing of objects and the corresponding solutions.
Zinc galvanizing – problems and solutions
| Problem | Solution |
|---|---|
| General dullness: | |
| 1. Too much or too little brightener | Perform a Hull-cell test (1 ampere – 15 min) to determine the correct amount. |
| 2. Bad ingredients out of balance | Perform a Hull cell test (1 ampere – 15 min) to determine the correct amount. |
| 3. Poor cleaning | Check the cleaning agents. |
| 4. High Temperature | Reduce the temperature to 27°C or add brightener to compensate (if no cooling is available). |
| 5. Insufficient agitation | Adjust the agitation. |
| 6. High pH | Lower the pH with hydrochloric acid. |
| 7. Low level ammonium chloride for the glazing agent | Perform an analysis to determine the correct addition (rapid increase in pH indicates low concentration of ammonium chloride agent). |
| 8. Organic Contamination or Metal Contamination | Treat with carbon: 0.5 to 1 gram per liter, or carbon together with 1 gram of hydrogen peroxide per liter. Treat the bath with 0.5 to 1 gram of potassium permanganate per liter. Treat with zinc dust. |
| 9. Low Chloride Content | Perform an analysis to determine the appropriate addition. |
| High current density combustion: | |
| 1. Excessive current | Reduce the amperage in the bath. |
| 2. Bad ingredients out of balance | Perform a Hull cell test (1 ampere – 15 min) to determine the correct amount. |
| 3. Low zinc concentration | Maintain the zinc metal concentration in an optimal range by adding zinc chloride. |
| 4. Low temperature | Increase the temperature to 29°C. |
| 5. Low level ammonium chloride for the brightener | Perform an analysis to determine the correct addition (rapid increase in pH indicates low concentration of buffering agent). |
| 6. High pH | Lower the pH with hydrochloric acid to 5.3 |
| 7. Low pH | Increase pH with ammonia to 5.3 |
| 8. Anode and cathode too close | Increase the distance between anode and cathode. |
| 9. Iron Contamination | Perform high current density dummy galvanization. |
| 10. Current is too high in the electrocleaner | Reduce the current in the cleaning bath. |
| 11. Insufficient agitation | Adjust the agitation. |
| 12. High chloride content | Perform an analysis and decant the solution. |
| 13. High Cl/Zn ratio | Reduce chloride additives. |
| High current density dullness: | |
| 1. High Temperature | Reduce the temperature to 27°C or add brightening agent to compensate (if no cooler is available). |
| 2. Low chloride content | Perform an analysis to determine the appropriate addition. |
| 3. Too much or too little brightener | Perform a Hull-cell test (1 ampere – 15 min) to determine the correct amount. |
| 4. Bad ingredients out of balance | Perform a Hull cell test (1 ampere – 15 min) to determine the correct amount. |
| 5. Low amperage | Increase the amperage. |
| 6. Metal contamination (Pb, Cd, Cu) | Isolate the source of the contamination from the electroplating solution. Perform an HCD dummy galvanization. Treat with zinc dust. |
| 7. High zinc metal concentration | Maintain zinc metal concentration in an optimal range by lowering chloride content, increasing pH, or decanting solution. |
| 8. High pH | Lower the pH with hydrochloric acid. |
| 9. Poor cleaning | Check the cleaning agents. |
| 10. Organic Contamination | Treat with carbon: 0.5 to 1 gram per liter, or carbon together with 1 gram of hydrogen peroxide per liter. Or treat the bath with 0.5 to 1 gram of potassium permanganate per liter. |
| LCD Dustiness: | |
| 1. Too much or too little brightener | Perform a Hull-cell test (1 ampere – 15 min) to determine the correct amount. |
| 2. Current too low | Increase the amperage. |
| 3. Low chloride content | Perform an analysis to determine the appropriate addition. |
| 4. Bad ingredients out of balance | Perform a Hull cell test (1 ampere – 15 min) to determine the correct amount. |
| 5. Metal contamination | Isolate the source of the contamination from the electroplating solution. Perform an LCD dummy electroplating. Treat bath with zinc dust. |
| 6. High pH value | Lower the pH with hydrochloric acid. |
| Reduced cover: | |
| 1. Low chloride content | Perform an analysis to determine the appropriate addition. |
| 2. High zinc metal concentration | Maintain the zinc metal concentration in an optimal range by lowering chloride or raising pH. Or decant the solution. |
| 3. Low pH | Increase the pH with ammonia. |
| 4. High pH | Lower the pH with hydrochloric acid. |
| 5. Too much brightener | Increase the temperature. |
| 6. Bad ingredients out of balance | Perform a Hull cell test (1 ampere – 15 min) to determine the correct amount. |
| 7. Low current Increase | the amperage. |
| 8. Low temperature | Increase the temperature to 29°C. |
| 9. Metal Contamination (Pb) | Isolate the source of the contamination from the electroplating solution. Perform dummy electroplating. Treat bath with zinc dust. |
| 10. Chromium contamination (above 10 ppm) | Treat bath with 0.25 g of sodium bisulphite per 1 litre. |
| 11. Organic Contamination | Treat with carbon: 0.5 to 1 gram per liter, or carbon together with 1 gram of hydrogen peroxide per liter. Or treat the bath with 0.5 to 1 gram of potassium permanganate per liter. |
| 12. Anode surface area | too smallAdd anodes. |
| 13. Too much peroxide added | Solution was treated too aggressively with peroxide. Perform Hull-cell test (1 ampere – 15 min) to determine the correct amount of brightener. |
| Blistering: | |
| 1. Poor cleaning | Check the cleaning agents. |
| 2. Too much brightener | Dummy plate. Treat the bath with 0.5 to 1 gram of potassium permanganate per liter. Increase the temperature of the bath to 43°C. Treat with carbon: 0.5 to 1 gram per liter, or carbon together with 1 gram of hydrogen peroxide per liter. |
| 3. High pH | Lower the pH with hydrochloric acid. |
| 4. Quality of the substrate | Find a suitable cleaning process for this substrate. |
| 5. Low chloride content for glazing agent | Perform an analysis to determine the appropriate addition (rapid increase in pH indicates low concentration of buffering agent). |
| 6. Organic or metal contamination | Treat with carbon: 0.5 to 1 gram per liter, or carbon along with 1 gram of hydrogen peroxide per liter. Or treat the bath with 0.5 to 1 gram of potassium permanganate per liter. |
| 7. Chromium contamination (above 10 ppm) | Treat bath with 0.25 g of sodium bisulphite per 1 litre. |
| 8. Copper in the acid | Change the acid solution. |
| 9. Electrical problems | Check the electrical contacts. |
| 10. Bath ingredients out of balance | Perform a Hull cell test (1 amp – 15 min) to determine the correct amount. |
| Roughness: | |
| 1. Poor filtration | Use a filter of 1 to 5 microns. |
| 2. High pH | Lower the pH with hydrochloric acid. |
| 3. Anode surface area | too smallAdd anodes. |
| 4. Bad ingredients out of balance | Perform a Hull cell test (1 ampere – 15 min) to determine the correct amount. |
| 5. Poor cleaning | Check the cleaning agents. |
| 6. Magnetized particles | Collect them with a magnet and filter the solution. |
| 7. Copper in the acid | Change the acid solution. |
| Brittle deposit: | |
| 1. Too much brightener | Dummy plate. Treat the bath with 0.5 to 1 gram of potassium permanganate per liter. Increase the bath temperature to 43°C. Or treat with carbon: 0.5 to 1 gram per liter, or carbon together with 1 gram of hydrogen peroxide per liter. |
| 2. Excess thickness of the zinc deposit | Reduce the electroplating time. |
| 3. Too little carrier agent | Perform a Hull cell test (1 ampere – 15 min) to determine the correct amount. |
| 4. High pH | Lower the pH with hydrochloric acid. |
| Pits and pinholes: | |
| 1. Too much brightener | Dummy plate. Treat the bath with 0.5 to 1 gram of potassium permanganate per liter. Increase the bath temperature to 43°C. Treat with carbon: 0.5 to 1 gram per liter, or carbon together with 1 gram of hydrogen peroxide per liter. |
| 2. High Temperature | Reduce the temperature to 27°C or add brightener to compensate (if no cooler is available). |
| 3. Organic Contamination | Treat with carbon: 0.5 to 1 gram per liter, or carbon together with 1 gram of hydrogen peroxide per liter. Or treat the bath with 0.5 to 1 gram of potassium permanganate per liter. |
| 4. Bad ingredients out of balance | Perform a Hull cell test (1 ampere – 15 min) to determine the correct amount. |
| 5. Low Chloride Content | Perform an analysis to determine the appropriate addition. |
| Uneven deposit: | |
| 1. Low temperature | Increase the temperature to 29°C. |
| 2. Too much brightener | Dummy plate. Treat the bath with 0.5 to 1 gram of potassium permanganate per liter. Increase the bath temperature to 43°C. Treat with carbon: 0.5 to 1 gram per liter, or carbon together with 1 gram of hydrogen peroxide per liter. |
| 3. Bad ingredients out of balance | Perform a Hull cell test (1 ampere – 15 min) to determine the correct amount. |
| 4. Chromium contamination | Treat bath with 0.25 g of sodium bisulphite per 1 litre. |
| 5. Quality of the substrate | Find a suitable cleaning process for this substrate. |
| 6. Too much peroxide added | Solution was treated too aggressively with peroxide. Perform Hull-cell test (1 ampere – 15 min) to determine the correct amount of brightener. |
| 7. Electrical problems | Check the electrical contacts. |
| 8. Metal contamination | Isolate the source of the contamination from the electroplating solution. Perform LCD dummy electroplating. Treat bath with zinc dust. |
| Poor efficiency: | |
| 1. Anode surface area | too smallAdd anodes. |
| 2. Low chloride content | Perform an analysis to determine the appropriate addition. |
| 3. Electrical problems | Check the electrical contacts. |
| 4. Low current Increase | the amperage. |
| 5. Low temperature | Increase the temperature to 29°C. |
| 6. Low zinc metal concentration | Maintain the zinc metal concentration in an optimal range by adding zinc chloride. |
| 7. Bad ingredients out of balance | Perform a Hull-cell test (1 ampere – 15 min) to determine the correct amount. |
| 8. Too much or too little brightener | Perform a Hull cell test (1 ampere – 15 min) to determine the correct amount. |
| 9. Low pH value | Increase the pH with ammonia. |
| Decreasing zinc metal concentration: | |
| 1. Anode surface out of balance | Adjust the anode surface. |
| 2. High pH | Lower the pH with hydrochloric acid. |
| 3. Electrical problems | Check the electrical contacts. |
| 4. High drag-in and drag-out | Overhaul rack and drum operations and equipment. |
| Increasing zinc metal concentration: | |
| 1. Low pH | Increase the pH with ammonia. |
| Inappropriate use of additives: | |
| 1. High Temperature | Reduce the temperature to 27°C or add brightener to compensate (if no cooler is available). |
| 2. High pH | Lower the pH with hydrochloric acid. |
| 3. Bad ingredients out of balance | Perform a Hull cell test (1 ampere – 15 min) to determine the correct amount. |
| 4. Organic Contamination | Treat with carbon: 0.5 to 1 gram per liter, or carbon together with 1 gram of hydrogen peroxide per liter. Or treat the bath with 0.5 to 1 gram of potassium permanganate per liter. |
| 5. Too much peroxide added | Solution was treated too aggressively with peroxide. Perform Hull-cell test (1 ampere – 15 min) to determine the correct amount of brightener. |
| 6. Drag-in of low pH rinse water | |
| Rising solution pH: | |
| 1. Bad ingredients out of balance | Perform an analysis to determine the appropriate addition (rapid increase in pH indicates low concentration of buffering agent). |
| Stains after electroplating: | |
| 1. Poor rinsing | Increase the water flow. |
| 2. Excess time between plating and | rinsingReduce the transfer time. |
| 3. Weak nitrogen dip | Change the nitrogen dip solution. |
| 4. Rinse water temperature is cold | Increase the temperature or rinse time. |
| 5. Contamination in rinse water | Turn the water into a rinse tank. |
| 6. Metal contamination | Isolate the source of the contamination from the electroplating solution. Perform LCD dummy electroplating. Treat bath with zinc dust. |
| Blackness in HCD after clear dip: | |
| 1. Iron contamination | Isolate the source of the contamination from the electroplating solution. Perform LCD dummy electroplating. Treat bath with zinc dust. |