How to Spray Zinc Coatings
Zinc coatings are a wicked coating to apply. They are harsh on equipment and often a challenge to apply well. In this article will cover the common problems that are encountered with spraying zinc, how best to overcome them, and things to consider when spraying Zinc coatings including equipment setup considerations.
The typical challenges that occur when spraying Zinc involve its tendency to settle out during application, its high viscosity, as well as its short pot life. Zinc is a heavy bodied material and distinctly separates into the heavy bodied metallics and thinner liquids, if left at rest for a period of time. To compensate for this issue you have to include agitation on your pressure pot. For 2.8 gallon pots direct drive propeller agitators are sufficient but with pots of 5 or 10 gallon you often need a gear reduced agitator to allow for increased power delivered to the agitator to stir the material you also need paddles instead of a propeller on the end of the agitator. If using an airless paint sprayer Zinc can be kept in suspension by using a unit with a recirculating feature or by including an agitator on your bucket. If you will take breaks and have long fluid lines it can be important to keep the zinc circulating but with standard 50 feet of airless line the recirculating feature is usually not needed. Another important consideration is that you should mix the zinc before placing it in the pressure pot, the agitator itself will not sufficiently mix the material, it only helps keep the material in suspension. Pot life is a challenge as it will limit application time before it hardens in your pump or pressure pot. To overcome this challenge it is important to be aware of your pot life and avoid spraying close to the maximum pot life described. This can be accomplished by mixing smaller batches if it is to difficult to apply larger batches of coating. It is also important to remember that their will be time needed to clean out a pressure pot as well as airless hose so be sure to leave time for that when considering how long to spray with zinc before cleaning your equipment. Due to the heavy bodied nature of Zinc your application methods are typically limited to conventional air spray and airless paint sprayers. The important thing to remember about the airless paint sprayer is that the ratio cannot be higher than 40:1. If you use more than 4,000 PSI of pressure to drive an airless paint sprayer with Zinc you will pack the zinc out causing an inability to spray. The final thing to be aware of when spraying Zinc is whether it is water or solvent based. With water based coatings galvanized pressure tanks are sufficient but with water based Zinc or any water based coating you should be using stainless steel pressure tanks to prevent corrosion. By following these simple rules about spraying Zinc you can ensure a headache free zinc application experience. How about you what challenges have you had spraying Zinc?