The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California

Care And Repair Of The House

Sometimes the keys or clinches that hold the plaster to the base break off or become loosened and cause the plaster to bulge and crack. On ceilings especially, it will often hang in this condition for a long time before falling off, being held together by the hair or fiber in the plaster. Occasionally the nails or fastenings used to hold lath in place may corrode and break, allowing that part of the plaster covering the loosened lath, or laths, to sag and crack. Repairing Structural Cracks.

Tools.

For cracks and small holes a small diamond-shaped mason's trowel or broad-bladed putty knife, for plastering larger areas a plasterer's trowel and a shallow pan.

Materials.

Plaster of Paris or commercial patching plaster, a small amount of ordinary glue if necessary, and clean water.

The repair of structural cracks, or cracks extending through the plaster to the base, does not require refinishing of the whole surface, and. consequently, may readily be done by the unskilled workman.

To repair a deep crack, it is necessary to have the crack wide enough so that the fresh plaster may be forced in and form a good bond with the old plaster. If the crack is not sufficiently wide, it should be scraped with a knife blade until the opening is at least one-quarter inch across. All particles of loose sand and plaster should be brushed out and the surface should be thoroughly wetted before the fresh plaster is applied. The plaster should then be pressed well into place and struck off flush with the surface of the main body of plaster. If the old plaster has not been thoroughly wetted, it may draw the water out of the fresh plaster to such an extent that it will not set, but will dry out and remain in a chalky condition without appreciable strength. The drying out may be avoided by spraying water onto the surface after the plaster has set, and keeping the surface damp for a period of about 24 hours.

Shrinkage Cracks.

Shrinkage cracks, which usually occur only in the finish coat, are generally so numerous, if the job has not been well done, that it is necessary to refinish the whole surface, which work requires the services of an experienced plasterer.

Holes in Plaster.

The loose plaster around each hole should be removed, the remaining sound plaster wetted thoroughly, and the plaster applied in the same manner as prescribed for structural cracks. Because larger amounts of plaster are usually required for holes than cracks, it is advisable to retard the setting of plaster so that it may be worked for a longer period. (The process of retarding is explained later in this discussion.)