In an unusual climax to the "soap wars" saga, the association festooned a press conference with faded pyjama tops and displayed eight of its staff in tested garments, several of them damaged by Persil Power.
Clothes washed in the original Persil Power had only 40 per cent of the strength of those washed in Ariel Ultra, Persil's chief (non-manganese) rival, according to the association. Even those washed in Persil Power after it had been reformulated had only70 per cent of the strength of garments washed in Ariel.
The tests cost the association £50,000, involved 100 people wearing 200 viscose shirts and cotton pyjamas for 17 weeks - a total of two "person years" - and were described by Derek Prentice, assistant director, as the biggest tests "we or any other consumer organisation in the world" had conducted on a washing powder.
Mr Prentice said the aim was not to act as referee between two "warring multinational giants" - Unilever, whose Lever Brothers subsidiary makes Persil, and Procter and Gamble, manufacturers of Ariel - but to clear up the confusion among consumers resulting from a "marketplace failure".
Andrew Seth, managing director of Lever Brothers, described the tests as "restricted and unrepresentative" and rejected the association's call for an explicit warning on Persil Power packets saying the product should not be used for coloured clothing.