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Testing Down Quality: Fillpower

PHD Testing

Fillpower is the prime indicator of down quality. It establishes the volume which a measured weight of down will fill — the fillpower — usually quoted in cubic inches per ounce. So when people talk about 700, 800, 900 down,  they mean how many cubic inches one ounce of that down will fill. 900 fillpower down is better than 800 down, because one ounce of 900 fills 100 cu.in. more than an ounce of 800 and more filled air-space means more warmth from the same weight.

PHD uses a Lorch machine for fillpower testing. This is as near to being an accepted world standard test machine as there is and it is approved by the International Down & Feather Bureau (IDFB). The standard Lorch test gives a fillpower figure about 4% lower than the US Federal method for the same down, so all PHD figures would be 4% higher if the tests were carried out under the US Federal method. 

Our suppliers quote us figures from the tests in their own IDFL-approved laboratories for every batch of down. Then we test it again in our factory, because we keep a very long record of all the down we handle and we need to know that every batch matches up to previous standards (as a cross-check we keep several of the old samples too, some of them for years).

New Fillpower Classifications

Why have we changed our fillpower figures in 2014?  PHD’s 1000 down is the same unbelievable performer that it was when we introduced it as 900 back in 2008. But in recent years a new method of testing fillpower has been adopted across the global down processing industry, giving a higher fillpower figure than before for the same down.

At PHD we have our own testing facility and we can ensure the quality of the downs we use as always. The problem arose over what to call it, 900 fillpower (measured by PHD) or 1000 (the lab figures from our suppliers)?  800 fillpower (PHD) or 850, even 900 sometimes (suppliers)?  Fillpower is a useful simple measure of down quality, but communicating the figures had become more complicated.

As we were determined to continue to verify the quality of all the down we use, we decided we had no choice but to update our own testing procedures to come into line with current international practice. With the assistance of both Lorch and the International Down & Feather Laboratory we have done that, and our new figures reflect this adjustment. We send batches to the IDFL for an independent quality check, but our own tests are now in line with the international industry standard.

Our down quality is the same as before, so why the fuss?  For practical purposes there’s no need. But when we’re using fillpower as shorthand for quality, it’s been useful to clear up the mixed messages.

The new figures you see for our downs are the result of our own tests and will remain so.  It has even been interesting to remeasure some of the old test samples we have retained of downs we were using years ago: one sample of the old 900 amazed us by achieving a figure of 1072 cu.in. under the new procedure.

Any of our customers, who have previously bought PHD gear with 900 down and are wondering if they have missed out, can rest assured that the new 1000 down item is identical  — in fact they’ve just had a free upgrade!

Read about down / feather ratios.

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