1. Helping prevent paint-job do-overs on a molecular level
particles - where science matters
  • Helping prevent paint-job do-overs on a molecular level

    By Kelly Hall, 3M Storyteller

    Rolls of painter’s masking tapes

    • Image of hands applying painter’s masking tape to trim and baseboard

      One of the fastest and most popular ways to give a room a facelift is to freshen it up with a new coat of paint.

      In fact, the right interior paint color can help catch a buyer’s eye and even boost the value of your home by as much as $5,000.

      While making the commitment to tackle a paint job is exciting, the preparation stage may not generate the same enthusiasm. This step can be a time-consuming part of your project – time that teams of scientists don’t want you to waste. That’s why they took a journey into a microscopic world to create a solution.

      You may never imagine the household item they helped create has anything to do with ionization – a scientific process by which electrically neutral atoms or molecules form ions by acquiring either a negative or positive charge by gaining or losing electrons. Ionization is what makes the adhesive attached to painter’s masking tapes help block paint from seeping onto various surfaces, like walls, wood floorstrim and baseboards. The outcome? A clean paint line.

      The beauty of how the tape works remains within its many layers.

    “It reminds me of cooking. You just have to be fearless, and you have to be inventive and imaginative and try new flavors and new things.” - Liz Johnson, 3M scientist

    • Scientists Mahfuza Ali and Liz Johnson
      Scientists Mahfuza Ali and Liz Johnson

      Getting along

      “There are five different layers in our tapes that all have to get along,” says 3M scientist Liz Johnson, who worked with a team to create the adhesive. Part of getting along means withstanding all environmental conditions. “We can put them in a hot truck and bake them. We can put them in the cold on a truck in Alaska. They have to endure these conditions and work the same, no matter what,” she adds.

      “We tested the tape with accelerated high humidity and temperature conditions. In real life, the tape will face lesser environmental conditions,” says Mahfuza Ali, a 3M corporate scientist who worked with Liz.

      Each roll of tape also needs to master the art of sticking securely, never falling off and unrolling without sticking to itself too much – something that takes more than you might realize.

      Peeling back the layers

      Liz remembers the specific moment when she and Mahfuza thought of a solution that would stick. “Mahfuza and I met in her office, and the ideas started to fly,” says Liz. “A truly incredible collaboration was born.”

      The result? They brought a new-to-the-world type of pressure sensitive adhesive to life. It makes up the Pressure Sensitive Adhesive (PSA) layer in the painter’s masking tapes.

      “This sticky polymer layer will adhere where you want your tape to stick, but also come off cleanly when you want to remove it,” says Liz.

      “It has excellent cohesive strength and can be removed from the surface without leaving any adhesive residue to the surface,” adds Mahfuza.

    Graphic illustrating the five layers of painter’s masking tape

    • How does it work?

      The PSAs are made up of polymers with unique charge properties. “This allows the polymers to have highly controllable physical properties, an ease of synthesis and versatility of applications,” says Liz.

      “The permanent cationic, or positive charge, carried by the PSA’s polymers blocks the migration of anionically, or negatively charged, stabilized suspensions such as paint,” explains Liz.

      The tape wasn’t always designed this way. The first version of the tape used a cationic charge coating on the edge of the tape, but Liz and her team wanted to make the tape easier to manufacture and easier to handle. “We decided to put that positive charge into the adhesive itself, to eliminate an extra coating step and the possibility of the tape coming off,” says Liz. “We were able to lock that positive charge into the backbone of the adhesive that’s on the tape. So, it can’t go anywhere and when you make the tape, it’s automatically there.”

    • Making the adhesive: You can see the IR lamps heating the initial emulsion mixture so that it can react. All the monomers will become a polymer.
      IR lamps heat the initial emulsion mixture so it can react. All the monomers will become a polymer.

      Stirring up a solution

      The adhesive is manufactured in a pot of water. “You put all the ingredients in the pot and heat them up until the reaction occurs,” says Liz. Because of this, there aren’t any harsh chemicals to work with when drying or manufacturing the adhesive.

      “It reminds me of cooking. You just have to be fearless and you have to be inventive and imaginative and try new flavors and new things,” says Liz. “For things that may not be typical, we said, ‘Why not try it? Let’s see what happens.’”

      Their team made more than 200 different variations of chemistries to test in small vessels and coated samples with each of them. “We certainly were not limited by the bounds of what we thought should work or what we thought would be right,” says Liz.

      Diving deeper

      Liz and Mahfuza’s team worked with other 3M teams to create additional layers within the tape. The primer layer, for instance, sits between the PSA and the tape’s backing to help the PSA adhere to the backing. “You want the PSA to stay with the paper backing – and not get left behind on your wall – when you remove the tape,” says Liz. “So, the PSA needs to stick to the backing with greater strength than it sticks to your wall or whatever else you might stick your tape to.”

      Another layer? The barrier coat: a coating applied to the paper backing to make the tape less permeable to liquids that we might accidentally expose it to while painting. It helps prevent paint from permeating, or infusing, through the tape you’re using.

      Lastly, the Low Adhesion Backsize (LAB) layer is coated onto the outside of the backing of the tape to prevent the PSA from sticking too much to the paper backing when the tape is rolled up. The tape must stay in roll form, so the PSA needs to stick a little to the LAB – but the tape needs to be easy to get off the roll. This means the PSA can’t stick too much to the LAB. “It is a very delicate balancing act to get the PSA and LAB to interact just right and remain the same, even if subjected to various temperatures,” says Liz.

    • Paint equipment and tools scattered across a plastic tarp

      The big reveal

      Once your painting preparation is completed, the rest of your project should be smooth sailing. Pretty soon you’ll be ready for “the big reveal,” which Liz describes as pulling of the tape, seeing a nice straight line and embracing how your vision came to life.

      For Liz and Mahfuza, their big reveal happened the moment they realized the technology they created in a pot of water could become something big.

      “With any new invention, the satisfaction and euphoria is enormous. At the beginning, you worry about if your idea will be able to solve all criteria,” says Mahfuza. “With diligent work and many sleepless nights, we were able to cross every hurdle.”