Copyright Goodheart-Willcox Co., Inc. Chapter 12 Laying Brick 237 15. Tool or strike the joints when the mortar can be indented with a thumbprint without too much pressure (“thumbprint hard”). See Figure 12-40. If the mortar is too wet, the brick will be smeared. If too dry, the mortar will turn black from metal worn off the jointer. Use the short jointer for vertical or head joints. These joints are done first. See Figure 12-41. Then strike the bed joints using the long jointer. See Figure 12-42. With the edge of the trowel, cut off the tags of mortar that were forced out by the jointers. See Figure 12-43. To remove the tags, move the trowel horizontally along the joints. 16. Brush the wall when the mortar is stiff enough, Figure 12-44. Brushing may be done at the end Trade Tip Be careful not to smear the tags or other mortar into the brick. Once adhered to the brick, mortar is difficult to remove. of the day or more frequently, if desired. Brushing reduces the amount of cleaning required later. 17. Lay successive courses in the same manner until the wall is the required height. See Figure 12-45. Code Note Tooling Mortar Joints The National Concrete Masonry Association (NCMA) identifies the process of striking mortar joints. They stipulate that head joints should be struck first and bed joints second. NCMA identifies striking joints too early will cause them to shrink away from the masonry units being laid. Tooling too late will cause the joints to darken because of the pressure required from the tool. They recommend using the “thumb” test to determine the appropriate time to strike joints. Mortar joints should be struck when a thumb is pressed into the surface of the joint without leaving cement paste on the thumb. For more information on mortar joints, refer to TEK 05-16 publication from NCMA. Author’s image taken at Job Corps, Denison, IA Figure 12-40. A masonry student is demonstrating the procedure of using a thumb print to determine if the mortar joint is ready to strike. Author’s image taken at Job Corps, Denison, IA Figure 12-41. When the mortar joints are ready, they are struck with an appropriate jointing tool. A short jointer is used to strike the head joints. Head joints are struck first. Continued Author’s image taken at Job Corps, Denison, IA Figure 12-42. Bed joints are struck last with the long jointer, sometimes called a sled-runner. Author’s image taken at Job Corps, Denison, IA Figure 12-43. Remove the mortar tags by moving the blade of the trowel forward along the head and bed joints.