The very best cement mortar should be used for pointing, as the best becomes dislodged all too soon. Clear portland-cement mortar is the best, although 1 volume of cement to 1 of sand is frequently used in first-class work. The mortar, when ready for use, should be rather incoherent and quite deficient in plasticity.
Before applying the pointing, all mortar in the joint should be digged out to a depth of at least 1 inch; or, better, in setting the stones, the mortar should be kept back an inch or more from the face, and thus save the labor of digging out the joints preparatory to pointing. For the bed joints this may be accomplished by keeping the mortar back from the face of the wall about 3 inches, and then when the stone is put into place the mortar will probably be forced out to about 1 or inches from the face of the joint, and conse quently little or no labor will be required to dig out the mortar. Frequently in laying a stone the mortar is spread to the very edge of the joint; and then when the pointing is done, it is so difficult to dig out the mortar that the joint is cleared only about half an inch deep, which depth does not give the pointing sufficient hold, and consequently it soon drops out. The difficulty of digging out the mortar from the vertical joints may be obviated by bending a strip of tin or thin steel to the form of a U having one leg considerably longer than the other, and nailing the long leg to the side of a light strip of wood so that the closed end of the U will project beyond the edge of the wood a distance equal to the depth of the pointing, and then inserting the closed end of the U in the vertical joint before it is filled with mortar.
When the surplus mortar has been removed, the joint should be cleansed by scraping and brushing out all loose material, and then it should be well moistened. The mortar is applied with a mason's trowel, and should be well "set in" with a calking iron and hammer. The joint should be rubbed smooth and finished even with the pitch line or with the face of the stone. In the very best work, the joint is also rubbed smooth with a steel polishing tool. Walls should not be allowed to dry too rapidly after pointing; and therefore pointing in hot weather should be avoided.
There are four general forms of finishing the edges of the horizontal joints of cut-stone masonry—whether or not they are formally pointed as above described. Fig. 74 shows these four forms. When the horizontal joints are finished as in either of the first two examples in Fig. 74, it is customary to finish the vertical joints by the first method; but when either of the last two methods is employed, it is used for both the vertical and the horizontal joints.
Occasionally in cut-stone masonry, and frequently in brick masonry, the weather joint is improperly made to slope in the opposite direction, due to the fact that the mason stands at the back of the wall and "strikes" the joint by reaching down and resting the edge of the trowel on the stone below the joint. If the mason stands behind the wall, it is not comfortable to make the weather joint as shown in Fig. 74, at the time the masonry is laid. The grooved joint is fre quently called a tuck pointed joint, and is sometimes made with a V-like face. The beaded joint is not very durable, since the pro jecting portion soon becomes detached. In making the beaded joint, the beading tool is sometimes guided by a straight edge, called a "rod," and the joint is then said to be " rodded." Amount of Mortar Required. The amount of mortar required for ashlar masonry varies with the size of the blocks, and also with the closeness of the dressing. With I- to i-inch joints and 12- to 20-inch courses, there will be about 2 cubic feet of mortar per cubic yard; with larger blocks and closer joints, i.e., in the best masonry, there will be about 1 cubic foot of mortar per yard of masonry. Laid in 1 to 2 mortar, the former will require I to of a barrel of cement per cubic yard of masonry exclusive of the rubble backing (for which see $ 577); and the latter about half as much.
For the quantities of cement and sand required for a cubic yard of mortar of different compositions, see Table 22, page 120.