Why specify superdurable powder coatings?

There was a time not too long ago when trying to locate a building using superdurable polyester powder coating was akin to navigating through a ‘Where’s Wally’ book. Today, however, it’s difficult not to walk or commute through town and city centres without noticing a new development being decorated by enhanced durability finishes.

Super durable polyesters have been in existence since the early 1990’s, but for a while, super-durable specifications were preserved only for prestigious landmark buildings. Up until the start of this decade, standard polyester was very much the default position for specifiers owing to cost and relative specification inertia – people were used to it and accepted its durability credentials.

However, as those buildings from the late 70’s to early 90’s started to age, the limitations of standard systems became increasingly visible through colour fading and premature loss of gloss. This coincided with the rising expectations of a buildings design Life and the need for the full façade envelope to offer a longer service life.

Ultimately, the goal is to ensure the building looks good for as long as possible without the need for repainting: this is the primary function of super durable polyesters.

The most illustrative way in which these technologies can be compared in the ‘real world’ is through analysing coated panels that have been externally exposed in a natural weathering station in south Florida.

The diagram highlights two panels that have been exposed to the UV for a period of 5 years. On the left is a panel coated in standard polyester. The panel to the right is formulated in the advanced durability polyester. The top quarter of the panel has been masked off whilst the remaining face is exposed at a 45° angle south facing elevation. The original colour and gloss specifications are identical.

The differential in aesthetic performance is clearly evident and is largely determined by the composition of the polyester resin which essentially acts as a layer of sun block.  To provide some context, a year’s exposure in Florida equates roughly to 10 years in Northern Europe terms. This is largely down to both the number of days of sunshine these panels are subjected to in a calendar year and the relative strength of the UV itself.

Consequently, it is now commonplace for specifications to stipulate either a 3 year Florida exposure as prescribed by Qualicoat, who are responsible for the terminology ‘Class 2’ in reference to high durability powders; or 5 years as outlined by American standard AAMA 2604.

AkzoNobel’s Interpon D2525 complies with both specifications and comes with an extended guarantee of up to 40 years (UK application only) coupled with a reduced maintenance schedule (typically once every 18 months).

With a 27 year track record in the field, you will now find leisure centres, council offices and affordable homes adorning D2525 finishes in the same manner as a monumental skyscraper.