However, as it cross-links it also becomes less effective as an adhesive and eventually the tape carrier falls off, leaving solid, discoloured adhesive behind. At this stage there's not a lot a conservator can do. Tape removal is a pretty common activity for book and paper conservators, and here's a quick rundown of how it goes. If the tape is relatively new and has not had time to cross-link extensively, it has a better chance of being removed without leaving discolouration behind.
The tape in the top image still has sticky adhesive underneath the carrier, and the one in the bottom image has solidified. For the bottom image, the process of removing the tape is simply lifting the carrier and then attempting to remove the solidified adhesive underneath mechanically with a microspatula and scalpel without damaging the material underneath. In this situation I could remove some of it, but the adhesive does not always remain on the surface of the paper.
Here's an "after" picture for reference:. To begin with, I had to remove the carrier from the page. To do this I used a hot air gun to carefully loosen the adhesive and used tweezers to gently lift the carrier as I went along. All this does is warm up the rubber adhesive so that it becomes more flexible and easy to manipulate.
Some adhesive will remain on the page even after the carrier is gone, so it's important to remember to put waxed paper between the pages to prevent them from sticking together if you are going to close the book. While the discolouration and trapped dirt is noticeable, it's a bit hard to capture stickiness in photos, but the shine on some of these may give an idea. Removing the adhesive is fairly straightforward but a time-consuming process.
Since rubber is nonpolar I chose to use heptane to loosen it and remove it, but the decision of which solvent to use depends on situation and conservator's choice and experience. Depending on the amount of cross-linking and the formulation of the adhesive to begin with, other solvents or mixtures of solvents might be more effective. Generally you want to choose the safest solvent available that can still do the job. I did this, by the way, with proper fume extraction and nitrile glovesdon't try it at home.
The adhesive is traditionally rubber-based and is made so that it bonds with what it touches when pressure is applied. When self-adhesive tape was first invented this was a big deal, since before the adhesive would have to be triggered by heat, water, or another solvent.
The rubber like adhesive, is a long polymer chain just like the cellulose that makes up paper. Over time as the paper and the adhesive on the tape stay stuck together, the two types of polymers begin to interact and attach to each other. This process is called cross-linking, and this change to the chemical structure causes the sellotape to become insoluble and discolored.
The longer this goes on, the more difficult it is to remove the adhesive from the paper and the more discoloured it becomes.
However, as it cross-links it also becomes less effective as an adhesive and eventually the tape carrier falls off, leaving solid, discoloured adhesive behind. But then, because of their elasticity, they will resist separation when stressed.
Adhesion is the binding force between two different materials, whereas cohesion is the binding force between two similar materials. When two materials are brought into contact with each other, the surface molecules interact, giving rise to attractive forces that may be physical, chemical or electrostatic corresponding to adsorption, covalent bonding or van der Waals forces, respectively.
When the molecules are dissimilar, as in the case of a glue molecule and a molecule of the substrate the surface the glue is sticking to , the adhesive force holds the glue to the substrate. This site uses Akismet to reduce spam. Learn how your comment data is processed. Heritage Preservation Atelier Virtus Et labor.
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In adhesion , one type of molecule is sticking to another type of molecule; in cohesion , one type of molecule is sticking to itself. Tape uses both [source: Scientific American ]. The molecules of the adhesive stick to the molecules of the substrate, or adhere, but they also stick to each other, or cohere. If this weren't the case, the adhesive substance wouldn't hold together. The release coating prevents cohesion at the surface of the tape so it can be unrolled easily.
And so, what began as masking tape and some very happy auto painters is now an industry unto itself. Adhesive tapes have wrapped the metal skeletons of blimps to prevent corrosion. They've insulated at least one lunar lander and helped Apollo 11 astronauts carry out some on-the-moon repairs to their lunar module's fender [sources: ACS , NASA ]. They hold rearview mirrors onto cars and keep millions of scrapbookers from tearing their hair out when their placement is a millimeter off [source: 3M ].
In searching for more information about the tape used by NASA to insulate a lunar lander specially developed for the purpose, with the ability to remain sticky through an enormous temperature range , I also found pictures of the Apollo lander patched together with plain old duct tape, and came across an interesting phenomenon: Conspiracy theorists have decided the presence of duct tape on the Apollo lander confirms the moon landing was a hoax.
It's a probably a common viewpoint, that tools we have lying around the house couldn't possibly be used to get men to the moon. And in this case, it was actually just a quick repair to the lander's fender, which fell off during the mission. But duct tape also played a significant role in getting the ill-fated Apollo 13 astronauts back to Earth, and my point is simply this: I learned in my research that adhesive tape was truly a revolutionary development [source: Universe Today ].
In defense of pressure-sensitive adhesives, if the moon landing was faked, duct tape probably isn't proof of it. Sign up for our Newsletter! Mobile Newsletter banner close. Mobile Newsletter chat close. Mobile Newsletter chat dots. Mobile Newsletter chat avatar. Mobile Newsletter chat subscribe. Everyday Innovations. How Adhesive Tape Works. The Science of Stickiness " ". Pressure-sensitive adhesives make packing tape stick to the box on contact.
Turning Sticky into Sticky Tape " ". Adhesive tape even appears as the occasional fashion statement: For rapper Nelly, pictured on the shoot for music video "Dilemma" in , it was a signature look.
Backing -- The backing is what faces out after you apply the tape, and it doesn't stick to your fingers. Materials vary by application, but mixtures based on plastics, paper or cloth are typical.
Primer -- An adhesive primer is applied to the backing to help the adhesive stick evenly and securely to the backing material once applied. Adhesive -- A thin layer of adhesive is sprayed onto the primed backing material. Release coating -- The adhesive is covered by a coat of anti-cohesion material often polyvinyl carbamate to keep it from sticking to itself when rolled up.
Lots More Information Author's Note: How Adhesive Tape Works In searching for more information about the tape used by NASA to insulate a lunar lander specially developed for the purpose, with the ability to remain sticky through an enormous temperature range , I also found pictures of the Apollo lander patched together with plain old duct tape, and came across an interesting phenomenon: Conspiracy theorists have decided the presence of duct tape on the Apollo lander confirms the moon landing was a hoax.
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