The nature of Duresco and petrifying liquid, and the proper way to use them on damp walls has been explained as follows: - Duresco is a water paint consisting of pigments ground up in a medium containing water; petrifying liquid, as made by the Silicate Paint Co., is a solution containing certain chemicals which combine with stone, etc., to form a hard, impervious coating; the same result is obtained when Duresco is thinned with the petrifying liquid and applied to walls. For application to damp walls, the Duresco body colour must be thinned with petrifying liquid or Duresco liquid in the proportion of 1 to 4. Duresco is very often effectual on interior damp walls, hut the benefit cannot be considered permanent, as continual dampness entering the walls from the outside rots the plaster. Duresco is no good in cases of dampness arising from foundations. The cause of the dampness must first be removed. Three coats of Duresco should then be applied thinned down with the petrifying liquid. Petrifying liquid alone will prevent moisture penetrating, but is not so effectual as Duresco, and is only used where a painted effect is not required. Three coats of this should also be given. Duresco and petrifying liquid are both patents.

For porous bricks, Duresco should be applied outside the house.