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Tech Tips:

for Printing on Plastics and Synthetic Papers

Selecting The Correct Material And Material Handling

1 Consult your Transilwrap sales representative prior to selecting the material. The final application can have a tremendous influence on the product recommendation. Sheet size, thickness, amount of ink, one or two-sided printing, end application, and many other factors can influence the recommendation. 2 Condition the products to be printed in the pressroom environment for a minimum of 24 hours, 48 hours or more if possible. Colder or warmer outdoor temperatures require longer conditioning times. Open all pallets and remove packaging material to allow air circulation. Cold material will inhibit the drying process and should be avoided. 3 Run small lifts; 2"­3" maximum. 4 Use large diameter offset powder (50 micron), and use the minimum needed to prevent offsetting. Excessive powder, when combined with static inherent in plastic products, can cause ink pull, which gives a mottled appearance. 5 Infra-red lamps can be used to assist drying, but the temperature should be kept no higher than 95 degrees Fahrenheit. An aqueous coating may be helpful in drying and achieving a smoother finish. 6 Maximum press speed should be 5,500 IPH on conventional offset presses. Slightly higher press speeds have been obtained with UV presses and/or more experience. 7 Handle the products as little as possible, both before and after printing. Excessive handling can cause static build-up before printing and increases the potential for offsetting after printing.

8 Use static eliminators on the printing press. Units should be installed at the feed and delivery ends of the press. a. A "Transvector" type unit is recommended for the feed section. Transilwrap's Technical Service group can recommend a legitimate supplier. b. Keep blanket pressures at a minimum to reduce static build-up in the press. Excessive pressure is unnecessary and not only increases static generation, it reduces the life of printing blankets. c. The printing press should be properly grounded to permit static build-up in the press to escape. Please contact the manufacturer of your press for instructions. 9 Information to control static has been attached. The document is titled "Recommendations to Control Static in Plastic Sheet." 10 Two Sided Printing a. Let your ink supplier know you will be printing the job two sides. Transilwrap suggests doing drawdowns on both sides of the sheet. Slight side-to-side differences are inherent. b. Caution should be taken when planning to print on two sides and using an aqueous coating. The use of aqueous coatings or varnishes can be detrimental when printing twosided. The aqueous coating can be, and often is, the cause of gas ghosting. With these coatings, the chemical components escaping from the wet ink cannot spread out and exit the space between sheets. These gases are forced to travel

Transilwrap has assembled these printing tips for your benefit. We include these suggestions to help give you the best possible chance for success when printing on Transilwrap's products. Should you need additional help or information, please contact our Technical Service department at

1-800-441-0433

directly through the coating, thereby striking the reverse side of the next sheet. This constant chemical bombardment can actually "etch" the printed image into the surface of the unprinted sheet. When this happens, the surface tension, or dyne level, is reduced to the natural level of the substrate. Any corona treatment which had been applied is lost. 1. If gas ghosting occurs, the situation might be remedied by applying a sizing to the sheet. Talk to your ink supplier about sizing if this is the case. 2. Another remedy, provided the job is reasonably small, is to wipe the sheets with a solvent. Often times, a blanket wash, type wash, ink wash, or naptha will remove enough of the gas ghosting to permit the job to be saved. c. Print the second side of the sheet as soon as possible after the first side is complete. This generally means DO NOT WAIT LONGER THAN 24 HOURS to print the second side. Your Transilwrap sales rep can recommend a work-and-turn time that is appropriate for the substrate, ink coverage and pressroom conditions. d. Use as little ink coverage as possible to print the first side of the sheet. This will help control and possibly eliminate gas ghosting. Consider printing the side with the least print coverage first.

Selecting The Proper Ink

11 Talk to your sales representative for ink recommendations if you are new to printing on plastics. 12 Use only oxidizing inks specially formulated by your ink supplier. Have your ink supplier do ink drawdowns on actual production material before printing every new product lot. 13 Use fresh inks. Chemical changes can occur as inks age, thereby altering the suitability for specific substrates. 14 Run as little ink as possible. Use a more heavily pigmented ink rather than increasing ink film thickness with a weaker ink. 15 If a coating is to be applied over the ink, be sure it is compatible with the ink. Use the same manufacturer for both ink and coating, if possible. If this cannot be done, have your ink and coating manufacturers work together to insure compatibility. Just because a coating works well with one ink or substrate doesn't mean it will work with all of them. 16 Surface energy (dyne levels) can change over time. It can also be different from lot to lot, and even from side-to-side on the same product. Surface energy is nearly always different from one substrate to another. Because of this, do not assume one ink will work for all of your plastic substrates.

PRODUCTION NOTES: Printed on Transilwrap's 12 mil PRO-Print® synthetic paper with Transilwrap Fountain Solution and Wikoff Color Corp.'s Hy-Litho Process Inks on a MAN Roland 8 color press.

©Copyright 2001. Information and text are the intellectual property of Transilwrap Company, Inc. for the specific benefit of its customers in using its materials. Do not copy without express written permission.

Literature # 71701

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