Penetration depth and redistribution of an aqueous ammonium phosphate solution used for porous limestone consolidation by brushing and immersion

When consolidants are applied to porous stones, redistribution may occur inside the pore system after the treatment application, which influences their final penetration depth and performance. In this paper, the kinetics of redistribution were investigated for a 2-step hydroxyapatite-based consolidant, applied by brushing and immersion. The results of the study indicate that both the application method and the drying phase are crucial in determining the final penetration depth, the amount of hydroxyapatite that forms and the redistribution kinetics. In all cases, the limewater poultice applied during the second step of the treatment proved to be effective in removing soluble compounds.