The Consumer Council on Monday offered a timely reminder ahead of a drop in temperatures this week, saying that filling compositions for three double duvets fell short of claims.

Its findings came after tests conducted on 20 duvets filled with down, pure silk, synthetic fibre or wool.

The watchdog found that duvets from Cottex and Polotex only had 50.5 percent and 23.1 percent wool, respectively, with the rest of the fillings made up of polyester fibres, even though both products were labelled as being pure wool.

Collection de Chambre's synthetic fibre duvet also saw a discrepancy of 15.4 percent between the actual and labelled amount of soybean protein fibres.

Council chief executive Alaina Shum said the test results had been referred to the Customs and Excise Department for follow-up action.

"If the actual composition of the filling material does not match the labelling, it can affect the consumer's expectation regarding the duvet's performance, including thermal resistance as well as other aspects such as the weight and the softness," she said.

Cottex's agent, upon receiving the council's report, had immediately conducted a test themselves that showed that the filling was 100 percent wool, Shum noted.

The agent, she said, used a sample from its current stock while the watchdog had obtained the Cottex duvet for testing from a retail store back in February.

As for Polotex, its agent has referred the test result back to its manufacturer and suspended importation of its duvets.

Two of the washable duvets – one down and the other made with synthetic fibres – shrank by about seven percent in width after five washes.

As for flame retardancy, only the pure silk duvet from Cherry showed progressive smouldering in a test involving a lit cigarette.

The watchdog called on consumers to wash duvets only during a change in seasons or when necessary so as to reduce the chance of affecting their performance.

They should also take reference from other buyers and e-commerce platforms on top of the council's test results when it comes to selecting duvets, it added.