Very helpful training videos on pulp and paper. A minor issue on this one is that the table of Dye and Pigment listed direct dye as Anionic, but the previous slides says it is Cationic?
Hi, thank you for your question. I think you are talking about Optical Brightening Agents, (OBA's) These are complex organic molecules, often based on the basic stilbene molecule. The take in UV light, and then re-emit it in the blue part of the spectrum. Because of the way the human eye is, it thinks the paper is whiter.
