Bleached paper

Mills bleach paper for three reasons: printability (high-contrast ink), food contact (where brown paper is unacceptable), and aesthetics (white packaging signals premium). The choice of bleaching sequence is one of the bigger capital decisions a mill makes.

ECF bleaching, the dominant modern method, uses chlorine dioxide rather than elemental chlorine. TCF skips chlorine compounds entirely and uses oxygen, ozone, and peroxide. TCF is more expensive but produces no chlorinated dioxin byproducts; ECF is the practical default for most North American mills.

Bleaching reduces fibre strength slightly because the same chemistry that removes lignin also shortens cellulose chains. Receiving teams sometimes see this as a difference in burst or tensile values between bleached and unbleached grades of the same nominal basis weight.

Bleached grades carry distinct codes on shipping documents — often prefixed with 'BL', 'B/W', or 'mottled white' depending on whether one side or both sides are bleached.