One problem that occurs frequently with new Terrazzo floors is a cloudy or milky surface appearance. Contractors often meet little success in their efforts to eliminate clouding because they most often attempt to correct the situation with repeat applications of the same materials and procedures that permitted the original difficulty. Such measures would be successful only if the original problem was created by inefficient workmanship which is seldom true. The basic chemistry that occurs when cement sets creates this situation, and it is compounded by the failure of cleaning chemicals and processes used in trying to remove and eliminate the residue of the cement chemistry from the floor’s surface.
To explain more fully, the components of Portland cement powder change their physical and chemical form when combined with water. One of the end products of this combination is Calcium Hydroxide, which results at a rate of about six-tenths of a pound for each pound of cement used. This Calcium Hydroxide is better known as lime. Most of this converted lime is used to bind the Terrazzo together, but there is a certain amount of free lime that remains on the surface and in the pores of the floor after the final grinding.
Water, by itself, is capable of dissolving only about one-sixteenth of the free lime. The remainder must be disposed of by other means. Clear water flushing and scrubbing will not be totally effective in removing all of the free lime from the pores of a new Terrazzo surface. A detergent action is needed. It is an established fact that Terrazzo cleaners should be neither acid nor highly alkaline. Rather, they should be neutral. Being neutral, however, is not the only important factor; Being effective is most critical. Furthermore, soap is a combination of fatty acid oils and alkaline materials.
Detergents, on the other hand, are synthetic products that act in the same general manner as soap but are most effective in their performance. Some of the most popular chemicals used for cleaning Terrazzo are soaps rather than detergents. The makers of these popular soaps have cleverly made their product neutral but have balanced the alkaline component in such a way that it does not completely react to all of the fatty oils. This is much like the TV ad in which the daughter asked, “Mom, where is the bath oil?” and the mom replies, “It’s in the soap!” When these soaps are used on a floor, they leave a thin film of this un-reacted fatty oil, which will shine when the floor is buffed after it dries.
The clouding problem occurs when this film entraps and reacts with the residue of free lime on the floor causing insoluble calcium scum. Repeating the cleaning procedures with the same materials only adds to the condition. Applying a primer, sealer or wax on top will lock in the scum under a transparent shield. This makes everything worse for the sealing film must then be removed to expose the source of the problem for corrective treatment.
This situation can be prevented or minimized by thorough cleansing of the floor with proper chemicals before using any sealer or other film or scum forming surface treatments. Nonionic neutral detergents will thoroughly clean a floor without reacting to or combining with any free lime deposit or residue. The preceding relates to preparation of a floor for delivery to the owner, but long range maintenance programs with this type of film-forming soap also have limitations. The oily film never really hardens, so it will continue to trap dust and dirt. The cumulative effect of continuing use of such materials will cause even the most immaculate floor to become dull and lifeless. Detergents leave no oily film or residue to accumulate dirt. Your material suppliers should be able to help you distinguish between soap and detergents. For further information contact your Terrazzo contractor or the NTMA.