QUALICOAT UK & IRELAND
Choose Wisely
By Angus Mackie - QUALICOAT UK & Ireland Chair
There are many powder coaters in the UK who can offer to powder coat virtually anything from outdoor street furniture to small engineering parts for a wide range of applications . These companies offer flexible coating and curing oven arrangements to meet a wide range of items that require finishing . Powder coating is becoming the finish of choice for many manufacturers as an alternative to volatile solvent based paints . Powder based coating is kinder to the environment , producing less harmful waste .
Angus Mackie - QUALICOAT UK & Ireland Chair
Products that are powder coated for internal use such as white goods , furniture and electronic products , will last a lifetime once coated . Products that are exposed to outdoor weathering require additional consideration .
Two standards in the UK relate to powder coating onto steel products , these are : ‘ BS EN 13438:2013 Paints and varnishes - powder organic coatings for hot dip galvanised or sherardised steel products for construction purposes and ‘ EN 15773:2018 industrial application of powder organic coatings to hot dip galvanised or sherardised steel articles [ duplex systems ] - Specifications , recommendations and guidelines ’.
For powder coating onto aluminium , a different standard needs to be specified : ’ EN 12206‐1:2021 Paints and varnishes . Coating of aluminium and aluminium alloys for architectural purposes - Coatings prepared from thermosetting coating powder ’. Whilst powder coating onto a galvanised steel substrate requires minimal pretreatment prior to powder application , aluminium requires a comprehensive pretreatment system to be applied . Powder coating for architectural purposes is normally applied to aluminium extrusion and sheet aluminium but can also be applied to aluminium castings .
An unfinished aluminium surface naturally oxidises and this oxide forms a protective layer against further corrosion . As powder coating is porous , any application of powder coating onto unfinished aluminium , which is exposed to the weather , will eventually begin to oxidise under the powder coating and as a result , over a period of time , the coating will lose it ’ s adherence to the aluminium . This will often be experienced as flaking of the complete coating revealing the aluminium underneath .
Whilst the thickness and quality of the powder coat application is important for a good life expectancy , a poor pretreatment of the aluminium will result in failure over time .
There are basically three recognised systems of pretreatment of aluminium , chrome based systems , chrome-free systems and a preanodisation process . Each of these systems involves an extensive investment in either wet dip immersion tanks or various spray booths where the process of cleaning , rinsing , etching , rinsing , pretreatment , rinsing and drying of the aluminium can take place . Once applied correctly , the pretreatment offers a complete seal of the aluminium surface and an important ‘ key ’ for the powder to adhere too .
Together with the investment in additional pretreatment plant for powder coating
Pretreatment immersion tanks
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2 DECEMBER 2021 read online : www . surfaceworld . com