A primary tool is a notched trowel with the notches of   the   depth   recommended   by   the   adhesive manufacturers. A trowel with notches on one side and smooth on the other is preferred. Different sized trowels are available. A tile cutter is the most efficient tool for cutting ceramic tile. The scribe on the cutter has a tungsten carbide tip. A glass cutter can be used but quickly dulls. Use  tile  nippers  when  trimming  irregular  shapes. Nip off very small pieces of the tile you are cutting. Attempting to take big chunks at one time can crack the tile. A  rubber-surfaced  trowel  is  used  to  force  grout  into the joints of the tile. APPLICATION TECHNIQUES There  are  three  primary  steps  in  tile  installation: applying a mortar bed, applying adhesive, and setting tiles in place. Mortar Before  applying  a  mortar  bed  to  a  wall  having wooden studs, you first tack a layer of waterproof paper to the studs. You then nail metal lath over the paper. The first coat of mortar applied to a wall for setting tiles is a scratch coat; the second is a float, leveling, or brown coat. A scratch coat for application as a foundation coat must be at least 1/4 inch thick and composed of 1 part cement to 3 parts sand, with the addition of 10-percent hydrated lime by volume of the cement used. While still plastic, the scratch coat is deeply scored or scratched and cross scratched. Keep the scratch coat protected and reasonably moist during the hydration period. All mortar for scratch and float coats should be used within 1 hour after mixing. Do not retemper partially hardened mortar. Apply the scratch coat not more than 48 hours, nor less than 24 hours, before setting the tile. The float coat should be composed of 1 part cement, 1 part of hydrated lime, and 3 1/2 parts sand. It should be brought flush with screeds or temporary guide strips, placed to give a true and even surface at the proper distance from the finished face of the tile. Wall  tiles  should  be  thoroughly  soaked  for  a minimum of 30 minutes in clean water before being set. Set tiles by troweling a skim coat of neat Portland cement mortar on the float coat, or applying a skim coat to the back of each tile unit and immediately floating the tiles  into  place.  Joints  must  be  straight,  level, perpendicular,  of  even  width,  and  not  exceeding  1/16 inch. Wainscots are built of full courses. These may extend to a greater or lesser height, but in no case more than 1 1/2-inch from the specified or figured height. Vertical joints must be maintained plumb for the entire height of the tile work. All joints in wall tile should be grouted full with a plastic mix of neat white cement or commercial tile grout immediately after a suitable area of the tile has been set. Tool the joints slightly concave; cut off and wipe excess mortar from the face of tiles. Any spaces, crevices, cracks, or depressions in the mortar joints after the grout has been cleaned from the surface should be roughened at once and filled to the line of the cushioned edge  (if  applicable)  before  the  mortar  begins  to  harden. Tile  bases  or  coves  should  be  solidly  backed  with mortar. Make all joints between wall tiles and plumbing or other built-up fixtures with a light-colored caulking compound. Immediately after the grout has set, apply a protective  coat  of  noncorrosive  soap  or  other  approved protection to the tile wall surfaces. The  installation  of  wall  tile  over  existing  and patched or new plaster surfaces in an existing building is completed as previously described, except that an adhesive is used as the bonding agent. Where wall tile is to be installed in areas subject to intermittent or continual wetting, prime the wall areas with adhesive following the manufacturer’s recommendations. Adhesive Wall tiles may be installed either by floating or buttering the adhesive. In floating, apply the adhesive uniformly   over   the   prepared   wall   surface   using quantities  recommended  by  the  manufacturer.  Use  a notched  trowel  held  at  the  proper  angle  to  spread adhesive to the required uniform thickness. Touch up thin or bare spots with an additional coating of adhesive. The area coated atone time should not be any larger than that recommended by the manufacturer. In the buttering method, daub the adhesive on the back of each tile. Use enough so that, when compressed, the adhesive forms a coating not less than 1/1 6 inch thick over 60 percent of the back of each tile. Laying Tile The  key  to  a  professional-looking  ceramic  tile  job is to start working with a squared-off area. Most rooms do not have perfectly square comers. As a result, the first step is to mark off a square area in such a way that fractional tiles at the comers (edges) are approximately the same size. Begin by finding the lowest point of the wall you are tiling. From this corner draw a horizontal line one full tile height above the low point and extend 7-22