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jack archone having horizontal or nearly horizontal upper and lower surfaces. also called flat or straight arch.
jagged edgesirregularities left on the edges of the tile due to the use mainly of hand cutting tools.
jasper warea vitreous, opaque, colored unglazed ceramic ware having white or contrasting relief-decorations and containing a substantial amount of barite. originally developed by josiah wedgwood.
jiggeringorming ceramic ware from a plastic body by differential rotation of a profile tool and mold, the mold having the contour of one surface of.the ware and the profile tool that of the other surface.
jitterbuga grate tamper for pushing coarse aggregate slightly below the surface of a slab to facilitate finishing.
jointthe space between stone units, usually filled with mortar.
joint fillercompressible material used to fill a joint to prevent the infiltration of debris and to provide support for sealants.
joint sealantcompressible material used to exclude water and solid foreign materials from joints.
joint, controlsee expansion joint. joint, contraction. see contraction joint. joint, expansion. see expansion joint.
jointer (concrete)a metal tool about 6 in. (150 mm) long and from 2 to 41/2 in. (50’to 100 mm) wide and having shallow, medium, or deep bits (cutting edges) ranging from 3/is in. to 3/a in. (5 to 20 mm) or deeper used to cut a joint partly through fresh concrete.
jointing schemea detailed architectural drawing showing the dimensions, locations and configurations of stone units and joints on the structure.
journeymanan experienced reliable worker who has learned his trade and works for another person.
jumperin ashlar patterns, a piece of stone of higher rise than adjacent stones which is used to end a horizontal mortar joint at the point where it is set.