Offset printer – part 1
Prior to printing, leave the paper in the press room for at least two days to allow it to reach the same temperature as the surrounding air
Keep the paper wrapped for as long as possible to avoid moisture absorption, or less likely, evaporation when the level of humidity extremely low. The moisture content (relative humidity) of laser and copier paper is around 35% and this is much lower than that of the surrounding atmosphere. This low moisture content needs to be maintained to avoid reproduction problems later when the paper is used in a laser printer or copier.
Offset printer – part 2
Print the wire side first – paper is normally manufactured with a built-in controlled curl, making one side more suitable for laser printing/copying than the other. This is the under side of the paper or the wire side.
Wrapped paper is always packed with the wire side on the same side as the glued flap of the wrapper. Wrappers on some grades of paper are marked with an arrow to indicate the side on which the paper should be printed first. Bulk packed papers are always packed wire-side up.
Offset printer – part 3
Use special inks and varnishes – (if in doubt, consult your ink supplier) to avoid the possibility of ink build-up on the fuser roller of the laser printer or copier. Avoid cold-set conductive and rubber based inks and avoid foil blocking and thermography as these can melt during laser printing. Embossed or die stamped finishes may be flattened by the laser printer copier rolls.
Minimize damping – when possible, use an alcohol damping system.
Avoid the use of anti set-off sprays. If required, the use of anti set-off sprays should be kept to a minimum to avoid problems during laser printing or copying.
Offset printer – part 4
Cover paper immediately – after offset printing to avoid moisture absorption prior to cutting, conversion etc. Always indicate with an arrow, the wire side of the paper to avoid laser problems with laser printing or copying.
Guillotine with care – using a sharp blade to avoid subsequent feeding problems during laser printing or copying.
Rewrap in moisture proof wrappers – when final conversion is completed – and mark the wrapper clearly to indicate the wire side of the sheet.