The function(s) of soluble silicates in repulpinghashing and flotation deinking of waste newsprint/magazine were investigated extensively, under optimized conditions. During repulping/washing, silicate ’s response was characteristic of a buffer and a detergent. It was responsible for a 3.0% increase in I S 0 brightness. In repulping/flotation, silicate accounted for a 6.1% increase in I S 0 bri...