METHOD FOR REDUCING BRIGHTNESS REVERSION OF BLEACHED PULP CONTAINING LIGNIN BY FORMING THE PULP INTO SHEET FORM AND TREATING THE SHEET WITH A COMPOUND CONTAINING A FORMYL GROUP

A method and article of manufacture thereof is provided for reducing brightness reversion in bleached lignin-containing pulps or newsprint by the treatment of the bleached lignin-containing pulp or newsprint with a compound which donates a hydrogen atom to a photo-excited group or free radical more easily than does the lignin contained in the treated pulp. The hydrogen donating compounds include compounds with certain formyl functionality, including formate salts such as sodium, magnesium and calcium formate, formamides, formic acid esters, and formylurea. In one embodiment, calcium carbonate is added to enhance the activity of the formyl compound. The further addition of a trace amount of superoxide anion quencher such as copper sulfate or ascorbic acid is also provided to still further enhance the activity of the formyl compound, especially formate salts.