How Are Stick-on Bandages Made?
Most stick-on bandages are made of water-proof plastic. The bandages have gauze pads in the center, and they usually have holes in them that allow air to reach the injury. Stick-on bandages begin as long plastic sheets which have been coated with a sticky adhesive.
The coated plastic is cut into narrow strips and the soft gauze pads are pressed onto the sticky surface. The bandages are then sealed with pull-off tabs to keep them from sticking to things until they are used. Stick-on bandages stick tightly to skin, yet can be peeled off easily.
The stick-on bandage protects the wound and scab from friction, bacteria, damage, and dirt. Thus, the healing process of the body is less disturbed. Some of the dressings have antiseptic properties. An additional function is to hold the two cut ends of the skin together to make the healing process faster.
Why do bandages stick onto open wounds when we try to remove it?
Most wounds produce exudate (drainage) of some kind. This drainage is — in most cases — a mixture of serum (the non-cellular, liquid fraction of blood), white blood cells, bacteria, and dead skin cells.
The serum component of wound exudate contains molecules which are made to polymerize (form chains and clumps). In fact, these properties of serum are what allow our blood to clot, when we are injured.
When dry dressings made of cotton are placed on a wound, these polymers, and Fibrin in particular, form in the wound, and wrap around the dressing fibers, linking them to the wound bed (our healing tissue).
When the dressing is removed, these tenacious polymeric structures don’t want to let go, and tissue is inevitably torn away. In fact, this very property of dressings was among the first techniques used systematically in wound healing. They are called “wet to dry dressings.”