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Welcome to  ‘Ask The Expert’.  This page is moderated by industry consultant, Steve Wilkinson.  This page features the answers to your questions. Our visitors can also post comments to these questions/answers as well.  You can learn more about Steve’s background and our ‘Ask The Expert’ page by Clicking Here.

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November 24, 2010

Can you tell me what variety of materials is available for covering of corona treater rolls?

Dielectric materials, as they are known, come in three main types: Elasommeric, inorganics and plastics. The choice of which is suitable for you depends on the application, and of course each material has its own strengths and weaknesses.

Elastomics usually include silicone, bonded silicon and Hypalon, including some proprietary formulations. Hypalon was one of the most popular coatings but is very susceptible to pin holing and knife cuts. It is generally used on larger rolls.

Silicone is not only coated on a roll but can come in a sleeve form, which makes repair of the roll much quicker and easier. This makes silicone one of the most popular dielectric coatings. Epoxy coatings have generally been used as an alternative to Hypalon as it is less likely to pinhole and has reasonable cut resistance. Ceramic coatings have become very popular due to their excellent electrical and mechanical properties and lasts longer than most other materials.

Finally there is glass, which is applied in several layers using a casting method but has to be applied to specially formulated carbon steel due to the high temperatures needed to fuse the glass to the base material. The finished coating is very hard and dense and has a very smooth finish.

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November 8, 2010

Can you give me some suggestions on how to handle my inks more efficiently with less waste?

Ink is one of the largest consumable costs for all printers, not just in the cost per pound but also the cost of disposal, so efficient use of any ink is highly desirable from every aspect. The first step is to ensure that you are ordering not just the correct ink for the print application but more importantly that you correctly estimate the amount of ink needed for each job.

This is particularly important if you are using more specialized inks such as metallic inks. It is equally important to ensure that you try to schedule jobs with the same colors to run as a group so that you will save in press wash ups and unnecessarily contaminated ink when being drained back to their ink buckets or barrels. All inks should be carefully labeled so that every operator can easily identify them and (if you have bladed or two-roll presses) which press they were run on as the viscosity and chemistries may need to be different, and don’t forget the date of usage.

Try to always use your oldest inks first and always make sure ink lids are securely fastened down on all cans and drums. Use chambered ink systems for more efficient ink metering & lower ink volume, and use higher screen lower volume anilox with higher pigment strength inks to ensure the thinnest ink film possible. This will dramatically increase the mileage that you get from each pound of ink. Maintain your anilox to ensure you have minimum blocking of the cells so that you do not have to have your inks adjusted to compensate for the loss of volume from the anilox cells due to plugging. Ultrasonic systems do an excellent job of getting to the bottom of every cell and removing not just the pigments but the resins as well. If you are washing up the anilox on press, make sure that none of the wash-up solution gets into any fresh ink buckets. This is a major issue with water-based inks so great care should be taken to try not to let these inks dry on the anilox or other machine components. Blending your own colors from a base color ink kitchen is an excellent way of ensuring that you only mix the exact quantity of ink that you need for each job and also makes reworking of your inks easier as well.

With water-based inks make sure that your operators know how and when to measure the pH of the ink and how to adjust the viscosity as necessary. This will not only reduce your ink cost but also your waste costs. Make sure that you get ink draw downs from your vendor and check carefully against your color swatches when received and before you take the ink to press or pump up to the print deck. If you are using solvent or water-based inks and have the option to switch to UV inks this ink system will greatly reduce your ink consumption.

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