Complete these exercises at your leasure and mail me with your score. Good Luck!
As soon as the coating colour hits the web, there is an opportunity for water to migrate from the mix and into the sheet. What term is used when measuring this tendency?
Critical set point
Immobilisation value
Water holding capacity
Water retention value
To inhibit the uncontrolled movement of water out of the mix and into the sheet, what type of additive is usually incorporated into the coating colour?
Binder
Defoaming agent
Calcium Stearate
Rheology modifier
If the water in the coating moves too quickly, due to too much heat being applied, what problem can occur?
Binder migration
Pinholeing
Peeling
Streaking
How many types of coating pick have been identified?
2
3
4
5
What type of printing problem is most likely to be caused by uneven binder distribution on the surface of the coating?
Dry pick
Mottle
Set off
Wet pick
What conditions reduce the opportunity for binder migration?
High solids and high viscosity
High solids and low viscosity
Low solids and high viscosity
Low solids and low viscosity
Which drying method is said to offer the best drying rates whilst avoiding binder migration
Drum drier with forced air
Drum dryer without forced air
Infra red with forced air
Infra red without forced air
Paper and Board coating led to the development of which type of drying system?
Air Cap
Air float
Drum
Infra red
What is the typical velocity within an air in Air Cap dryer?
100-300 m/min
300-600 m/min
1000-3000 m/min
3000-6000 m/min
How much of the air passing through an Air Cap drier is typically recycled?
50-60%
60-70%
70-80%
80-90%
which type of drying system has the following advantages? Dries from both sides, Wide web tension range, Good web stability, Low energy usage
Air cap dryer
Air float dryer
Drum dryer
IR dryer
Which drying system makes use of the Coanda effect?
Air cap dryer
Air float dryer
Drum dryer
IR Dryer
What problem resulting from drying in Air Cap dryers led to the development of the Air Float Dryer?