The cleanliness of down is primarily evaluated by measuring the liquid level and water clarity of a down sample solution. The test involves observing the liquid in a graduated cylinder. According to U.S. national standards, the cylinder must be at least 550mm in height with a diameter of 30‒35mm.
During testing, the down sample solution is poured into the cylinder, and the clarity of the crosshair at the bottom of the cylinder is assessed to determine the down’s cleanliness. According to current U.S. national standards, the highest grade is 1000mm, which also serves as the benchmark for the so-called“ 1000+mm cleanliness” down commonly found in today’s market.
All aforementioned cleanliness tests are conducted in accordance with the IDFB Part 11-B standard.
Since 1908
With a history spanning over a century, Hop Lion Feather Works Corp. has developed and produced a wide variety of down and feather materials. However, is it possible to achieve an even higher level of cleanliness in down?
117 year
With a century of accumulated experience and exploration, we deeply understand that when it comes to down quality—regardless of fill power or composition ratio—the essence lies in preserving the essential natural oils while effectively controlling dust and other residue.
2025
Ultra Clean+
At the Hop Lion Down Laboratory, we are committed to preserving the natural properties of down while implementing multi-stage cleaning processes that are both environmentally responsible and of superior quality—setting a new benchmark for the industry. Furthermore, to drive the industry toward more scientific and refined cleanliness management, we have introduced an advanced testing standard of up to 3000 mm—equivalent to ten times the U.S. national standard. Hop Lion is dedicated to providing consumers with safer, higher-quality ultra-clean down, suitable for applications that demand the highest standards and a wider range of performance scenarios.
2025 Ultra Clean+
At the Hop Lion Down Laboratory, we are committed to preserving the natural properties of down while implementing multi-stage cleaning processes that are both environmentally responsible and of superior quality—setting a new benchmark for the industry.Furthermore, to drive the industry toward more scientific and refined cleanliness management, we have introduced an advanced testing standard of up to 3000 mm—equivalent to ten times the U.S. national standard.Hop Lion is dedicated to providing consumers with safer, higher-quality ultra-clean down, suitable for applications that demand the highest standards and a wider range of performance scenarios.
3000mm 10x
Minimum US standard for down turbidity: 300mm。
The entire water sample is poured into transparent test tubes with 3.5cm diameter. When the water level reaches 3000mm depth, the bottom cross-mark remains clearly visible to the naked eye.
For certain down materials, after processing into Ultra Clean+ Down, the dust content can be controlled to as low as 0.2%, which is one-tenth of the GB/T standard requirement.
3000mm 10X
Minimum US standard for down turbidity:10倍。
processing into Ultra Clean+ Down, the dust content can be controlled to as low as 0.2%, which is one-tenth of the GB/T standard requirement.
Since 1908, Hop Lion has built an unshakable fortress in the down supply chain over more than a century. Whether from the company’s own breeding farms or through wide-ranging, socially responsible sourcing, all raw materials undergo rigorous testing in our in-house down laboratory before shipment, with strict monitoring of every quality parameter.
Advanced monitoring systems continuously oversee the washing process, ensuring that repeated cleaning of the down does not damage the cluster cores or compromise the natural oils.
Hop Lion uses down detergents certified by Bluesign, free of APEO and chlorine bleach, providing zero structural damage to the down while being non-toxic, harmless, and environmentally sustainable.
Studies have shown that Ultra Clean+ down exhibits significantly reduced odor compared to conventionally cleaned down, while effectively minimizing residue and dusts.
After washing, down is sampled and tested in batches. Each sample is placed in pure water, agitated, and filtered. The filtered solution is then poured into a transparent cylinder with a 3.5cm diameter. When the water level reaches 3000mm, the crosshair at the bottom of the cylinder remains clearly visible to the naked eye, demonstrating the exceptional cleanliness of the down.
All the above test data were generated by the Hop Lion Laboratory as follows:
* Certain down materials, after thorough cleaning, can achieve a dust content as low as 0.2%.* Hop Lion Laboratory reserves the right of final interpretation.
