Low Phosphate Coating Weight
We are getting a low coating weight with an immersion zinc phosphate coating. Could pH be a factor in this issue?
Q. We are getting a low coating weight with an immersion zinc phosphate coating. I cannot locate the recommended pH operating range for this product, even on the Technical Data Sheet. My coating weights are about 300 mg/sq ft, and the free acid is higher than normal at about 6. With a bath temperature of 170ºF, the pH is currently at 2.08. Could pH be a factor in this low-coating-weight issue? D.K.
A. Without the data sheet it is difficult for me to give you a specific answer to your question. However, I can tell you that there are a number of other parameters, including chemical concentration, bath temperature, dwell time, etc., that can affect coating weight. If you are not satisfied with the achieved coating weight, I suggest you contact your local product salesman for guidance.
RELATED CONTENT
-
Paint Application Methods
An overview of spraying, dipping, flow coating, and everything in between.
-
Improving Transfer Efficiencies in Coating Operations
There are many methods for addressing electrostatic grounding in metal painting processes, and Tim Ulshafer from Mueller Electric says the best method for your process is a simple and worthwhile exercise.
-
A Current Affair: Examining the "No Amperage" Phenomenon
If you are performing a coating process that requires the use of a rectifier, you may have experienced the "no amperage" problem. Here's a look at the phenomenon and some solutions…