Figure 4-30.-Types of metal-sash glazing.nonporous surface. Figure 4-30 shows examples of thetypes of metal-sash putty. Elastic glazing compoundsmay be used in place of putty. These compounds areproduced from processed oils and pigments and willremain plastic and resilient over a longer period thanwill putty. A skin quickly forms over the outside of thecompound after it is placed, while the interior remainssoft. This type of glazing compound is used in windowsor doors subject to twisting or vibration. It may bepainted as soon as the surface has formed.For large panes of glass, setting blocks may beplaced between the glass edges and the frame tomaintain proper spacing of the glass in the openings. Theblocks may be of wood, lead, neoprene, or some flexiblematerial. For large openings, flexible shims must be setbetween the face of the glass and the glazing channel toallow for movement. Plastics and heat-absorbing orreflective glass require more clearance to allow forgreater expansion. The shims may be in the form of acontinuous tape of a butyl-rubber-based compound,which has been extruded into soft, tacky, ready-to-usetape that adheres to any clean, dry surface. The tape isapplied to the frame and the glass-holding stop beforethe glass is placed in a frame. Under compression, thetape also serves as a sealant.Glass may be held in place in the frame by springclips inserted in holes in the metal frame or bycontinuous angles or stops attached to the frame withscrews or snap-on spring clips. The frames of metalwindows are shaped either for outside or inside glazing.SETTING GLASS IN WOODAND METAL SASHESDo not glaze or reglaze exterior sash when thetemperature is 40°F or lower unless absolutelynecessary. Sash and door members must be thoroughlycleaned of dust with a brush or cloth dampened withturpentine or mineral spirits. Lay a continuous1/6-inch-thick bed of putty or compound in the putty run(fig. 4-31). The glazed face of the sash can berecognized as the size on which the glass was cut. If theglass has a bowed surface, it should be set with theconcave side in. Wire glass is set with the twist vertical.Press the glass firmly into place so that the bed puttywill fill all irregularities.When glazing wood sash, insert two glazier’s pointsper side for small lights and about 8 inches apart on allsides for large lights. When glazing metal sash, use wireclips or metal glazing beads.After the glass has been bedded, lay a continuousbead of putty against the perimeter of the glass-faceputty run. Press the putty with a putty knife or glazingtool with sufficient pressure to ensure its completeadhesion to the glass and sash. Finish with full, smooth,accurately formed bevels with clean-cut miters. Trim up4-26
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