Nicoat

Work-and-Turn

This Tech Note refers to two-sided sheet-fed jobs. Work-and-turn , work-and-flop, sheet-wise. Using water-based coatings, aqueous.

Timing Variables

There are many variables that determine the timing or when a job can be backed up. The most important factor is the formula of the coating. The water-based coating should be formulated for two-sided work. The coating should dry fast, dry hard and be able to pass a face-to-face, coating-to-coating, block test. Nicoat's block test is 2psi @ 140°F for 24 hours.

Drying Systems

Another important factor is the drying system on a press. Current drying systems include hot air, infrared and exhaust. Hot air, air movement, velocity and evacuation are key in the process of drying aqueous coatings. The infrared can help both the coating and the ink. Water-based coatings dry through absorption into the stock and evaporation of the water, ammonia and co-solvents.

If the drying system can assist in drying the coating faster, the job can be backed up sooner.

Substrate Type

The type of substrate and ink coverage also make a difference in when a job can be backed up. A premium 100 pound cover stock may need more time than a 14 pt. SBS C2S. A heavy four process job will need more time than light screen work. The type of ink used can play a significant role. Generally, a faster setting ink will improve turnaround.

Load Size

The size of the load needs to be considered as well as airing the loads. The smaller the load, and the more air introduced into the load, the faster a job can be backed up.

Coating Amount

Another factor affecting the timing of the two-sided work is the amount of coating applied. A general rule of thumb is the thinner the film or coating weight, the better. We recommend .5 to .75 wet pounds of coating per 1,000 square feet.

Pressroom Conditions

The less humid and cooler the pressroom (room temperature at 72°F), the faster a job can be worked-and-turned.

Rule-Of-Thumb

Although all of our customers operate under many different conditions, have various types of printing presses, coaters, drying systems and run different formulations, commercial printers successfully backup jobs within hours using our coatings. Most commercial printers, through their own experience, determine what works best for them.

All of the conditions discussed come into play when backing up a job. The learning curve comes quickly when factors such as coatings, ink, drying system, stock, coating weight and press conditions are taken into account on each specific job.