Dimples on a person’s face are usually regarded as being attractive and desirable. But dimples on the surface of paper application tape…not so much! In fact, dimples in the application tape are aesthetically unappealing. In most cases, however, a little dimpling does not mean the roll is bad and can’t be used. Generally, sign makers can easily work through this condition without experiencing problems.Sometimes, though, dimpling can contribute to wrinkles and bubbles when laminating the tape to vinyl graphics. When that happens, that could spell trouble. Here’s why. Wrinkles and bubbles in your application tape often result in wrinkles and bubbles in the applied graphics.
So what causes dimpling on the surface of application tape? And is there anything that you can do about it?
Dimpling is caused when a dried paper sheet absorbs moisture in the air. I have often observed dimpling in the summertime in humid parts of the country. As the paper facestock absorbs moisture, it expands resulting in dimples, tunnels and sometimes wrinkles. To minimize the dimpling there are steps that manufacturers, distributors and shop owners can take.
A significant part of the problem occurs in manufacturing. After the application paper is primed and coated with adhesive, the sheet is dried in a series of ovens. If the curing process is not controlled precisely, the paper can be over-dried. In addition to controlling the drying process, manufacturers can also re-moisturize the paper, after the sheet exits the ovens.
“Sometimes ‘over drying’ is not evident until the roll is unwrapped and is exposed to different levels of moisture at an end user’s location,” says Ken Graver, Operations Manager for RTape Corp. and CET Films. “Dimpling can occur in areas of extreme heat, cold or high levels of humidity. Paper is hygroscopic and will readily absorb moisture or dissipate it as it equalizes itself to the surrounding environment.”
Distributors and shop owners can also help control this problem. My first suggestion is to keep the rolls of application tape in their cartons until you are ready to sell it or use it. At RTape many of our larger rolls are packaged in clear plastic sleeves. When you remove these sleeves, you expose the paper to humidity. Keep the application tape covered. The sleeves also prevent the tape from getting dirty. If you are a shop owner, and part of your shop is air-conditioned, store the tape in air conditioned area.