Abstract: A water-based emulsion paint, for example, is formulated with high refractive index opacifying pigment particles, dispersant, and polymer particles in which substantially all of the pigment particles (40) are disjuncted from one another and contained within an attached cluster of polymer particles (41) or have appendant polymer particles to give opacifying units having a nodular outline. Preferably micro-voids are trapped between particles and the dispersant is less than 1% of the pigment by weight.

Abstract: The thickener comprises:(a) 25-45% of methacrylic acid, acrylic acid or a mixture thereof;(b) 25-65% of alkyl acrylate such as methyl acrylate, ethyl acrylate, butyl acrylate, alkyl methacrylate such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, lauryl methacrylate or a mixture thereof;(c) 1-40% of an ester of composition; ##STR1## in which R is a C.sub.12 -C.sub.25 alkyl group, n=at least 10; m=at least 5 A=H, --(CH.sub.2 CH.sub.2 O).sub.n --R, C.sub.1 -C.sub.20 alkyl,--(CH.sub.2 CH.sub.2 O)m-H or --(CH.sub.2 CH.sub.2 O).sub.m --CH.sub.3(d) 0-1% of a polyethylenically unsaturated monomer effective for chain branching or crosslinking such as diallyl maleate, diallyl phthalate, divinyl benzene, allyl methacrylate, ethylene glycol dimethacrylate, or trimethylol propane triacrylate,(e) optionally, but preferably, up to 10% of an ethylenically unsaturated hydrophylic monomer.