What’s Under Your Blankets?
When the moving truck arrived at our new home in Georgia years ago, my daughters, though young, were all on hand to help move the smaller boxes stacked in the dining room and carry them to the consequent rooms or closets in the house.
As they read the description of the contents on each box, my oldest daughter came across a different printed carton from our prior move to Texas. It was marked, “Mom’s Elementary Days.” Knowing this box contained her mother’s things from her childhood, she immediately set that box under an end table and continued distributing the others...or directed her two younger sisters on what they should do next.
Later that evening, she pulled the box out from under the table and then asked her mom if she could see what was inside. Her mother gave her the OK.
After digging through some old yearbooks and pictures that my wife had kept through the years of growing up, she came across a couple of plastic necklaces and key chains which fell out of a package. It was a Shrinky Dinks arts and crafts kit.
All three of my girls spent the next afternoon drawing and coloring on these unused sheets of plastic while my wife and I continued to open and put away more items from what seemed to be 200 boxes. As you can imagine, we both agreed to give up early and my wife then helped the girls put their little decorated cutout plastic designs onto a cookie sheet and then into the oven.
Once in the oven, the molecules in the plastic were activated by the heat and caused them to begin to squirm on that cookie sheet and shrink. After they were removed from the oven and cooled down, these tiny uniform objects were miniature replicas of what the three girls had created earlier in the day. They were totally amazed as they watched all of this take place through the oven door glass.
So if heat affects various plastics in a variety of ways, why use self-adhesive plastic as underlay for your blanket cylinder? What takes place to a sheet of perma-pack when the heat builds up?
Some may think they are saving time and/or possibly money by using the plastic in place of paper packing, but they are actually jeopardizing the quality of print. There is a certain amount of heat that builds up in the printing units where the UV lamps are located. This heat will pass through the blanket and affect the integrity of the plastic material underneath.
If you are currently using plastic blanket packing, measure the blanket height on each of your printing units. You will see a deviation from the units with the lamps vs. without. In fact, you will most likely find a variation between units with the lamps alone.
Do yourself a favor by removing the plastic and returning to the paper. Your printability will remain much more stable and consistent when all of the units are printing with the correct pressures.