APHA = Pt-Co = Hazen = PCU = Platinum Cobalt Color

Bottles of APHA/Pt-Co/Hazen 500 color standard.

“APHA” stands for American Public Health Association Color Scale, the organization responsible for the original definition and implementation of this visual color scale as a standard method for rating water quality. Continue reading

What is the relationship between the APHA/Pt-Co/Hazen and Gardner color scales?

The APHA/Pt-Co/Hazen and Gardner visual color scales were both originally based on liquid chloroplatinate color standards but have different history and intended use. Continue reading

Where does one find the EP (European Pharmacopoeia) Liquid Color Matching Standards?

 EP – European Pharmacopoeia Color is a visual liquid color scale used primarily in the pharmaceutical industry. It consists of 3 primary color standard solutions (yellow, red and blue) mixed with hydrochloric acid to make 5 standard color solutions – B (brown), BY (brownish-yellow), Y (yellow), GY (greenish-yellow) and R (red). Continue reading