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Powder Coating

• British Standards
• Guarantees

British Standards

There is considerable potential for confusion over the current standards for powder coating.

Powder coating for aluminium alloys

• BS EN 12206-1:2004 is the latest standard but there remain "unresolved performance issues" which have caused BSi to delay the withdrawal of BS 6496. Architects should be aware of the difficulties of specifying powder coating whilst these two standards are both current and a detailed discussion of the issues can be found at www.cliveplant.co.uk
• BS 6496:1984 (2000) is the 'old' British Standard which should have been superceded but which is still (May 2006) listed as current. BS 6496 is still invoked by NBS clause Z31/210 in Update 48 (November 2006).

Powder coating for hot-dip galvanized steels

• BS EN 13438:2005 is the latest standard and is generally considered an adequate replacement for BS 6497.
• BS 6497:1984 (2000) is the 'old' British Standard which remains current, but has been declared obsolescent.

Guarantees

Although guarantees are routinely requested, and are covered by NBS clause Z31/225, the real worth of such guarantees has been the subject of much debate over recent years as the wording has become increasingly complex and deliberately obscure. Points to watch out for include:

• Restrictions limiting the amount payable to the cost of the powder coating. This is ridiculous in the context of the cost of the coating relative to the total cost of the remedial works should the coating fail.
• Restrictions linking the validity of the guarantee to the timing of contract payments, i.e. a late payment from the fabricator to the applicator could invalidate the guarantee.
• Sliding scale payments, with the amount payable reducing over time.
• Specific time limitations. Examples include a reduced time period (10 instead of 15 years) for damage caused by filiform corrosion.
• Onerous maintenance requirements, particularly ridiculously frequent cleaning regimes or phrases such as "aggressive environments" which cannot be adequately defined.

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