Summary for powder coating smut Discussion
Smut on powder coated parts after curing is the issue raised here, with the poster describing a full pretreatment and coating sequence: degrease, chemical strip, DI rinse, air dry, sandblast, DI rinse, zirconium dip, 12+ hours drying, preheat at 120 °C for 15 minutes, cool, apply powder, and bake at 200 °C for 15 minutes. The excerpt does not include a diagnosis or final answer, so the page mainly documents the process and the symptom rather than a resolved cause. Based on the thread text alone, the likely value of the discussion is in comparing the coating steps against common sources of post-cure smut such as contamination, incomplete cleaning, or pretreatment issues, but no named responder’s advice is shown in the excerpt.
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Q. I have a problem with high gloss black. It usually happens on thick parts, die cast iron and die cast aluminum when I apply high gloss black powder on parts.
After curing there is some kind of grey smut all over the part. It can be wiped off with clean cloths or polishing machine. But sometimes I need to do a very hard wipe to get this smut off. Result is less gloss, less shine after wiping.
I need help to fix this problem please. I’ve been searching answer for a while but seems like no one has this problem.
The result came up as photo attached.
My coating procedure is:
– degrease
– Strip old color by chemical
– Rinse by DI. Water
– Dry by air blow gun
– Sandblasting
– Rinse by Di. Water
– Dip in Zirconium bath
– Dry by air for 12 hours+
– Heat up in gas oven before coating at 120 °C for 15 minutes
– Wait for temperature decrease
– Apply powder color
– Bake at 200 °C for 15 minutes
Kantinon Worawutwakin (Bell)
– Phitsanulok Thailand
May 14, 2024