How to Offset Print RPD RBD!

Transcription

1 Page 1 of 6 How to Offset Print RPD RBD! (Last Updated: 16 th of February 2011) RPD RBD can be printed through most printing methods, which include offset, gravure, flexography, screen and rotary. RPD RBD have advantages of pulp and synthetic paper. It can be easily printed by using common printing machines and methods. Moreover it has water resistant properties like the synthetic paper. We recommend the following when printing on RPD and RBD. Please note the following is only a guide. Settings can still vary between different printers and operators. 1. Regular ink and soy ink are adequate for RPD RBD print. 2. Printing speed is approximately 7500 ~ 8000 sheets per hour for dark / solid color, more than 9000 sheets for lighter colors. 3. Water feed is [Set 21 and Ratio 115]. 4. Ink feed is [Set 40 and Ratio 116]. 5. Drying powder is level 4~6, depending on artwork. 6. RPD and RBD s surface immediately dries after print. For RPD RBD to fully dry and ready for further prints or processes please allow approximately 1 hour after light color prints or 6 hours after dark color prints. 7. When stacking printed paper, please place separating plates as required. 9. To minimize static, please maintain at least 40% relative humidity. Anti-static equipment such as ionizing air units at feeder and/or delivery is preferred but not essential. 10. Please trim 4 sides of the paper where higher printing and conversion precisions is required.

2 Page 2 of 6 FREQUENTLY ASKED QUESTIONS (FAQ) The answers provided below are guides which can help first time users of stone paper. Q1 : Stone paper too soft to feed through the printing machine? RBD is a thicker and stiffer type of material thus it will not have feeding problems caused from paper that is too soft. In contrast, RPD paper being a softer material can at times cause some printers to print slower. Should printers find stone paper too soft to feed through the printing machines then one may consider the following to alleviate feeding problem. Change Paper Thickness Used: Generally printers printing paper above RPD 120micron in thickness will not find the material too soft for printing. Should you be printing on RPD 100micron and have troubles feeding the paper through then using thicker grades can be considered to increase printing speed. Adjust Conveyer Belts at the Paper Feeding Area: When feeding very soft paper at very fast speed, the edges of the paper can fly which can cause printing machines to print slower or often stop. This problem can be alleviated or solved when the belts are redistributed evenly across the paper, and ensuring there are belts located at both edges of the paper. This will ensure the paper is fed through with minimal flying if any, and thus assist in increase of print speed. Choice of Printing Machine: In general printing machines such as Roland and Heidelberg do excellent in printing on stone paper even the thinner softer series. Should the printing machine have anti-static equipments, turning on these can assist in the printing speed too.

3 Page 3 of 6 Q2. Ink not easy dry? Offset problems? Below are recommendations valid for both RPD and RBD paper. Weather: Humidity can affect the speed in which ink dry. Where it is a raining day and humidity tends to be higher, then it may take longer for ink to dry. On the other hand, should it be a sunshine day, where humidity tends to be lower, then for light print jobs only about 30minutes is required before turning over to print. On the other day should it be heavy print job 2~3hours will be required before printing on the reverse side. Stacking: Where it is heavy print jobs, do not stack the paper too high. We recommend keeping the print jobs in stacks of about 20cm in height. Height can be reduced and increased based if it is a light or heavy print job respectively. Hardening Agent: Often hardening agents are added in printing inks to reduce offset problems. However, using hardening agents on stone paper is not recommended, please refrain from using hardening agents when printing on both RPD and RBD stone paper. Q3. How to deal with recurring white spots? Please clean printing blanket when you see recurring white spots on printing material.

4 Page 4 of 6 Q4. Is there a recommended printing side? Side that Face the Sky: You will find that the recommended side of printing will always be the side that faces the sky for sheets that arrive on our pallets. Four Corner Bend Down: The difference between printing on one side of the RPD and the other side of the RPD is not obvious, nevertheless, it maybe helpful to understand and identify which side is the recommended side of printing to ensure higher printing precision and printing quality. When you lay RPD flat on the table, you will see four corners bend down towards the table (note this is very slight). When the paper bends down at the corners, the recommended printing side will be the side facing up, or the side you see on the table. For single side printing jobs, we recommend printers to print on the recommended printing side to ensure best results. RBD vs RBD: For RPD there is a slight difference between the two sides, this is not obvious in RBD. You will only need to follow the rule of printing on the side of the paper that faces the sky as it arrives in a pallet as a general rule. Q5. Any recommendations for printing RPD doublesided? RBD vs RPD: Doubleside printing on RPD requires a little more care than printing on RBD as RPD is a very soft material. Please consider the recommendations below for doubleside printing on RPD. Print Using RPD 160micron or Above: Should ink distribution for doubleside printing be even on both sides of the paper and generally light prints (e.g. maps) then using thinner grades of RPD such as

5 Page 5 of 6 RPD 100micron or RPD 120micron will be okay. However, should the print job involve a contrast of heavy solid color prints as well as light color prints on the same side or on both side, then using thickness below RPD 160micron is not recommended. Reason for this is because stone paper is very soft and as the uneven spread of ink dries it can result in uneven tension on the paper causing uneven flatness of the paper. When printers flip the paper to print on the second side after the paper becomes uneven, they may have difficulty with registration. So using either higher paper grammage, i.e. above 160micron, can greatly help alleviate this problem. Print reverse side first and recommended side second: For doubleside printing, we recommend printing on the reverse side of the paper first with the side with the lighter colored printing or more even colored printing side, before turning over to print on the recommended side for dark color or less even ink distribution side for printing. RPD stone paper has a slight curvature, the diagram below illustrates an exaggerated version of this curvature to help explain the printing steps. Figure: Recommended printing side: Print the reverse side first before printing on the recommended printing side. Suitable for printing heaving (dark) color ink or uneven ink distribution. Reverse printing side: Print this side first. Try to print this side with lighter color ink or even ink distribution.

6 Page 6 of 6 Q6. What is Stone Paper s thickness variation? Currently stone paper variation average: RPD +- 7%, RBD +- 6% Stone paper will of course only improve in thickness variation in the future.