As with all other building operations, the superintendent needs to be very watchful in inspecting the cut stonework and its setting, to prevent defects and imperfect work being imposed upon him. When a stone is once built into a wall it can only be removed at considerable expense and delay and much vexation, and it is therefore important that all defects be discovered before the stone is set. The superintendent must also be well posted on the various ways in which defects are covered up, so that he may discover them, if any exist, and have sufficient firmness to demand that all unsound or defective stones shall be replaced by sound ones, and that the work shall be done in the manner directed by the architect.
Defects. - The following are the defects most likely to occur in cut stonework.
Good granites are liable to contain local defects, such as seams, black or white lumps called "knots," and also brown stains known as sap. Any of these defects should cause the stone to be rejected. Seams may be detected by striking the stone with a hammer, and those which do not ring clearly should be rejected.
In sandstones the most common defects are "sand holes" (which are small holes filled with sand, but without any cementing material, so that the sand soon washes out) and uneven color. Stones from the same quarry often vary considerably in color, and the superintendent must see that the color of the stone is uniform throughout.
Patching. - Often in cutting stone a small piece will get broken from a large stone, and the contractor, rather than throw the stone away, will either stick the piece on again or cut out the fractured part and fit in a new piece. The pieces are glued on with melted shellac and then rubbed with stone dust until they cannot be noticed by a casual glance, and the superintendent must look sharply at the stones to be sure that they have not been patched in this way.
At first these patches are hardly noticeable and do no harm, but when the stone gets wet the patch becomes conspicuous, and in time the shellac in the joint is washed away and the patch drops off.
When the damaged stone is large, and cannot be replaced except at great expense and considerable delay, the superintendent might consent to have it patched, but he should see that it is done right, and, where possible, a square hole should be cut in the stone and a corresponding piece tightly fitted in, and then cut to fit the stone or moulding. If on the corner of a stone the piece can generally be dovetailed, so that it will stay in place without the aid of shellac. If any patched stones are put into the building the superintendent should know of it beforehand, and, as a rule, it will be wise to consult the owner of the building about it before the stone is set.
In the cutting of the stone the most common fault to be found is poor workmanship or too coarse a surface. Naturally the finer a surface is tooled or crandalled the greater the expense, hence contractors will generally finish the stone as coarse as they think the superintendent will pass. Very often, also, sufficient care is not taken in matching the ends of moulded belt courses, cornices, etc. The superintendent should insist that all the pieces are cut exactly to the same pattern, and that all edges are true and free from nicks.
It is a very common occurrence to find some window sills that are not of sufficient width to be well covered by the wood sill. The back of the stone sills should extend at least 1½ inches beyond the face of the wood sill, and the back of the wash should be cut to a straight line, without any holes or scant surfaces.
The ashlar, especially when rock-face, is apt to be too thin in places, and to have very poor bed joints. The superintendent should insist that the bed joints, top and bottom, be at least 3 inches wide at the thinnest part, and that they be cut square to the face of the work. He should also examine the stones to see that they have been cut so as to lay on their natural beds. The proper bonding and anchoring of the ashlar and trimmings should also receive careful attention. The anchoring of gable copings should be especially looked after, as it is not infrequent that such copings slide out of place and fall to the ground from neglect in this particular. One would naturally suppose that the builder himself would see that his work was done securely, if not handsomely; but it seems to be a general fault amongst builders to trust a good deal to luck, and to use as few precautions to insure it as possible. In these days, when everything is done with a rush, there are also many builders that are ignorant of the best methods of doing work, or that consider them unnecessary and not "practical."
When finials or similar stones are cut in two pieces they should be secured together by iron dowels set in almost clear Portland cement. The superintendent should constantly bear in mind that stonework cannot be too well anchored and bonded.
The superintendent should also caution the foreman, when setting arches, columns, etc., not to let the mortar come within ¾ of an inch of the face of the stone. Moulded arches, particularly, need to be set with great care, as if the mortar comes out to the face the joint may be a little full at the edge and cause the moulding to "sliver" or "spall" at the joints. It is not uncommon to see arch stones and columns cracked on account of neglect of this precaution.
When the pointing is being done the superintendent must carefully watch the operation of raking out the joints to receive the pointing. The old mortar should be raked out to the depth of at least ¾ of an inch. If the work is not watched, however, it may be found in a year or two that the raking of the joints was only partially done, if not neglected altogether, and that the pointing mortar was only stuck on to the face of the joint.
There will naturally be many other points in connection with the stonework that will require careful supervision to secure a good and durable job, but careful attention to those above noted will lead to a pretty thorough inspection of the whole work.