Foamable aqueous compositions can be foamed and applied to porous substrates to make light-blocking dry opacifying elements. Such compositions have 0.05-15 weight % of porous particles; at least 20 weight % of a binder; at least 0.0001 weight % of additives (including a surfactant); water; and at least 0.001 weight % of an opacifying colorant. Each porous particle includes a continuous polymeric phase and discrete pores; a mode particle size of 2-50 m; and a porosity of 20-70 volume %. The continuous polymeric phase T.sub.g is >80 C. and has a polymer viscosity of 80-500 centipoises at an ethyl acetate shear rate of 100 sec.sup.1 at a concentration of 20 weight % at 25 C. The dry opacifying element light blocking value is at least 4 and has a luminous reflectance >40% as measured by the color space Y tristimulus value. The foamed aqueous composition has a foam density of 0.1-0.5 g/cm.sup.3.