Spray has traditionally been the baen of our lives as print finishers because too much of it on the sheet surface can interfere very noticeably with both the visual quality of the job and the adhesion of the film to the sheet. Of recent times our change to water based adhesives and the increasing use of print sealers has reduced the numbers of problems to more manageable levels.

We still however see many jobs affected by irregular clumps of spray particles that we term 'spray bombs'. These are caused by clogged spray nozzles or by spray falling from gripper bars or machine parts in the print delivery. It is very difficult to clean a job once it is contaminated by spray bombs, and the usual resolution is to run it and sort after cutting into singles.

Recommendations

Please use the minimum amount of the finest grade spray powder needed to prevent set off.

Encapsulated powders are free flowing, even in humid conditions, and help to prevent clogging of nozzles.