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Cured Finish Appearance Problems

 

8. Coating Finish-Cured Films Appearances

What is the problem you are facing?

Dust, precured or other coarse material.

Possible Causes Possible Solutions
1a. Dust or other coarse parts on the metal surface.
1b. Dust or other coarse parts in powder.
1a. Check pre-treatment. High sludge level in phosphate bath.
1b. Check powder and locate the cause of this contamination;if necessary clean up the installation and use fresh or sieved powder.

 

Matting of powder surface.

Possible Causes Possible Solutions
1. Contamination with other powder (based on other raw materials). 1. Clean up the installation, if necessary contact your powder supplier.

 

Orange-peel.

Possible Causes Possible Solutions
1. Warming-up of the coated material is too slow or too fast. 1. Check curing-cycle and curing oven; if necessary contact your powder supplier.
2. Powder type too fast or too coarse particle size distribution. 2. Contact your powder supplier.
3. Moisture contamination. 3. Replace the powder.

 

Cratering.

Possible Causes Possible Solutions
1. Contamination with other powder (based on other raw materials). 1. Clean up the installation; if necessary contact your powder supplier.
2. Bad pre-treatment. 2. Check pre-treatment and if necessary contact pre-treatment supplier.
3. Contamination with incompatible materials from the spraying areas.
e.g. silicones.
3. Check the presence of incompatible materials : if necessary clean up the installation and contact your powder supplier.

 

Pinholing.

Possible Causes Possible Solutions
1. Humidity of the powder too high. 1. Check storage facilities. Powder shall be stocked at room temperature in closed packing (maximum humidity 75%).
2. Air entrapment with casting. 2. Preheat objects over 320 F (160ºC) and cool down before applications ( only galvanized), or contact your powder supplier, who can advise you a special developed powder.
3. Gas entrapment and escaping due to chemical reaction. 3. Keep coating thickness below 100 microns; if necessary contact your powder supplier.