Why the cartridges Unicel are they white ? I saw a filter cartridge with a filter fabric yellow on a trade show, what is this support ?

Unicel and virtually all the manufacturers of filter products use a material 100% polyester, spunbonded, called Reemay® as a carrier filter.

Reemay®, is FDA compliant, is approved for the filtration of milk and is white to indicate purity.

The material is yellowish (technically also a spunbonded polyester yarn) of less good quality and is less expensive.