Units of paper quantity as ISO 4046. In Europe, the DIN 6730 standard for Paper and Board includes a definition of 1 ream of A4 80gsm (80 g/m) paper equals 500 sheets. The word 'ream' derives from Old French "reyme", from Spanish "resma", from Arabic "rizmah" "bundle" (of paper), from "rasama", "collect into a bundle". (The Moors brought manufacture of cotton paper to Spain.) Early variant rym (late 15c.) suggests a Dutch influence. (cf. Du. "riem"), probably during the time of Spanish Habsburg control of the Netherlands. The number of sheets in a ream has varied locally over the centuries, often according to the
Paper machine consistency levelling chest having about 15 minutes retention. This is enough retention time to allow any variations in consistency entering the chest to be levelled out by the action of the basis weight valve receiving feedback from the on line basis weight measuring scanner. (Note: Many paper machines mistakenly control consistency coming out of the machine chest, interfering with basis weight control.) There are four main sections on this paper machine. The forming section makes the pulp into the basis of for sheets along the wire. The press section, which removes much of the remaining water via a system of