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Expiry date of powder used in powder coating?
December 9, 2014
⇦ (tip: readers rarely show interest in abstract questions, but people's actual situations usually prompt responses) 
Q. What is the general expiry date of powder used in powder coating?
Gopi Nath
- Mumbai, maharastra, India
A. Boxes of powder bought from reputable suppliers have a date on them, and storage conditions. Generally the higher the storage temperature the shorter the shelf life.
Often the expiry date is 2 years from manufacture if stored under 25 °C.
Some powders stored well seem to perform long past this (to 6 or 7 years), yet others don't perform at 3 years old.
Varies with powder chemistry too.
Geoff Crowley
Crithwood Ltd.
Westfield, Scotland, UK
December 12, 2014
July 13, 2017
Q. If we use expired powder in coating, then what are all problems will come?
antony samson- Chennai India
July 17, 2017
A. My experience {over 35 yrs} is that it is entirely dependent on the powder storage conditions.
I have successfully used 10 yr old powder.
The main problem is to recognise that powder is hygroscopic.
Basically, it absorbs water as anyone with an inadequately dry air supply line soon discovers to their detriment. An efficient air dryer must be incorporated into the air supply. Anyone who ignores this soon finds out to their frustration and cost what a pain blocked lines can be.
Keep your powder dry!!!!
Hope this helps,
Regards,
Bill
Trainer - Newcastle Australia
A. Geoff and William have given useful facts about keeping properties and for some commercial applications this may be enough though I would try a sample before starting any large or important job.
But don't even think about using outdated powders (or paints) if you are working to aerospace specifications.
It is, however, acceptable to return outdated materials to the original manufacturer for testing and re-certification.
Geoff Smith
Hampshire, England
July 18, 2017
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