Technical Guidance


Shelf Life

Powder Coatings should be stored in cool, dry conditions to ensure the coating continues to offer the chemical and physical attributes specified in its technical data sheet.

Although a time period is specified in the technical data sheet, practical experience has shown that provided the coating is stored in optimal conditions, the coating material will last for many years without losing any of the physical or chemical properties of the fully cured coating, including: weathering, corrosion resistance, or flexibility.

HMG always recommend spraying a small swatch to check the colour and gloss of any product before use.

Deterioration of Physical Aspects

Under good storage conditions what may deteriorate is the physical aspects of the powder coating in its dry powder form, i.e. it may agglomerate, causing the spraying of the coating to be problematic – surging in guns for instance.

Therefore, rather like an old tin of paint where it would be expected that it would require a good stir before using, the powder coating in its original plastic liner should be carefully taken out of the box and rolled gently around before being put back in the box and being ready for use; additionally, should the powder have picked up moisture, leaving the box opened to the atmosphere for a period of time will allow the humidity to equalise.  Alternatively, sieving the powder and/or fluidising the powder in a fluidised bed with clean, dry air will break up any small agglomerates.


If the powder coating is not stored under ideal conditions, sintering of the coating can occur and will result in hard lumps that cannot easily be broken up. 

Although sieving can correct the issue, very often the finished coating will not have the same flow and appearance as it once had.  Additionally, some epoxy and epoxy-polyester systems are more moisture-sensitive than polyester products, particularly low gloss systems.  Care should be taken to ensure the gloss level is still the desired effect.


We can make any powder coating colour or finish to order so get in touch to discuss your requirements.

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