Slides on small grains that have a big effect
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There are three main types of anti-setoff powders used in printing: calcium carbonate, sugar-based, and starch-based. Calcium carbonate is heavy and low-dust but needs to be surface treated to avoid abrasion. Sugar-based powder dissolves easily but cannot be used with dryers. Starch powder has spherical grains, flows well, and is gentle on machines. The key is selecting the right powder for the job and application method to minimize powder usage.
Slides on small grains that have a big effect
- 1. Small Grains that Have a Big Effect
- 2. Anti setoff Powders Anti setoff powders are used to create a gap between freshly printed sheets in order to ensure there is no ink transfer and to help the sheets dry a little faster. But which tiny microscopic grains of powder are best suited to which applications?
- 3. Types of Anti setoff powders In principle, there are three different types of powder. Some powders are made of calcium carbonate, some are sugar-based, and others are made of natural starch.
- 4. Calcium carbonate powder Calcium carbonate powder has a comparatively high weight, is relatively low-dust, and is not sensitive to static buildup during the powdering process. However, it is best to use a surface-treated version of this powder.
- 5. Continue… As the shape and hardness of untreated calcium carbonate means it can act like emery paper on the print sheet, printing plate, and machine components. It also tends to build up on the blankets during perfecting printing.
- 6. Sugarbased powder In contrast, as sugarbased powder is dissolved by the dampening solution, it barely builds up on the blanket and is suitable for several passes. The disadvantage of sugar-based powder is that it cannot be used with dryers.
- 7. Starch powder Starch powder has the most naturally spherical grains. This means it flows well and is particularly gentle on the machines. For perfect results, use a powder application system with static electricity eliminator.
- 8. Continue… The starch powder is also available in a water-repellent version designed specifically for water-based coatings, but not for multiple passes. It is also important to note that hydrophobic starch powder is not compatible with subsequent finishing operations.
- 9. The key things The key thing to bear in mind is that the powder has to be the perfect match for the print job at hand. The same is also true of the grain size of the powder – this is largely dependent on the print motif and respective area coverages.
- 10. Continue… As a rough guide, 20 to 25 micrometers is generally sufficient for print jobs with grammages of between 70 and 250 gsm. Grain sizes of 35 micrometers and over are becoming increasingly common for jobs.
- 11. Continue… Once the right powder has been selected, the next task is to ensure only as much powder as is absolutely necessary is applied to the paper – no more. The powder spray devices that do this have a tricky task to fulfill.
- 12. Continue… The functionality of the powder spray device can be tested by placing a black sheet under it and activating the test mode. If the sheet displays irregular powder distribution following the test job, the powder nozzles and supply lines should be checked for blockages.
- 13. Continue… Heidelberg recommends the starch-based powders Saphira Powder Pro 100-20 and Powder Pro 100-35. Both powders have a particularly uniform grain size. They are also ideal for use in the highly efficient Powder- Star devices from Heidelberg.
- 14. Continue… The combination of Saphira powders and PowderStar reduces the quantity of powder required, leads to less contamination in the delivery, creates a better ambient climate, and causes less wear on presses and peripherals.
- 15. Contact Us… Mr. Rajendra Prasad Rajendra.prasad@heidelberg.com www.heidelberg.com Copyright 2014 Heidelberg India, all Right Reserved. Heidelberg India keeps member Printing industry informed about its latest development and attractive offers.
- 16. Thank you