Jagged edges

Irregularities left on the edges of the tile due to the use mainly of hand cutting tools.

Jasper ware

A vitreous, opaque, colored unglazed ceramic ware having white or contrasting relief-decorations and containing a substantial amount of barite. Originally developed by Josiah Wedgwood. (ASTM C 242).

jiggering

Forming 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. (ASTM C 242).

Jitterbug

A grate tamper for pushing coarse aggregate slightly below the surface of a slab to facilitate finishing.

Joint filler

Compressible material used to fill a joint to prevent the infiltration of debris and to provide support for sealants.

Joint sealant

Compressible material used to exclude water and solid foreign materials from joints.

Joint, control

See 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.

Journeyman

An experienced reliable worker who has learned his trade and works for another person.