A few weeks ago I rendered a few internal window reveals with sand and cement and water mixed (in the correct proportions) with this waterproofer. I tipped out what was left in the bucket on to a carrier bag and forgot about it. Yesterday morning, for an experiment, I partially submerged a few pieces of various sizes in a tray of water. Most of the material of these pieces were well above the water level. However, by late afternoon, all of the pieces were completely saturated with water. To my surprise. This can't be right can it? I would expect the top of these pieces to remain perfectly dry. Is waterproofing only achieved by closing in the surface, or is this an ineffectual product?