Sanitary pads are designed to absorb and contain menstrual fluid, providing hygiene and comfort during menstruation. These disposable products are engineered with multiple layers, each serving a specific function to manage fluid effectively. Their primary purpose is to absorb fluid away from the body, preventing leaks and maintaining a dry feel for the user.
The Outer Layers of a Pad
The top sheet, or cover layer, is the part of the sanitary pad that directly touches the skin. This layer is engineered for comfort and to quickly wick menstrual fluid into the pad’s core. Common materials for the top sheet include non-woven synthetic fibers such as polypropylene or polyethylene, which are soft and permeable, allowing liquid to pass through while feeling dry. Some pads also blend synthetic fibers with cotton for enhanced softness.
Beneath the absorbent core, the back sheet serves as a waterproof barrier. This layer prevents absorbed fluid from leaking through the bottom of the pad and staining clothing. It is typically constructed from a thin, impermeable film of polyethylene, a type of plastic, which effectively contains the liquid.
Sanitary pads are secured to underwear using adhesive strips. These strips are covered with peel-off paper until use, and once exposed, they adhere the pad firmly in place. The adhesive provides a strong grip to fabric, preventing the pad from shifting, yet allows for easy removal without residue.
The Absorbent Core Explained
The absorbent core is the main component of a sanitary pad, capturing and holding menstrual fluid. A primary material within this core is cellulose pulp, often from wood pulp. This natural material draws in fluid through capillary action and distributes it throughout the pad’s inner structure. The pulp provides bulk and initial absorption capacity, forming the foundation of the pad’s fluid management system.
Working in conjunction with cellulose pulp are superabsorbent polymers (SAPs). Sodium polyacrylate, a granular SAP, can absorb hundreds of times its weight in liquid. When fluid comes into contact with sodium polyacrylate, it rapidly transforms into a gel, locking the liquid away and preventing rewetting. SAPs allow pads to be thinner while offering high absorbency, enhancing comfort and discretion.
The combination of cellulose pulp and superabsorbent polymers within the core optimizes the pad’s performance. Cellulose pulp provides initial rapid absorption and distribution, while SAPs efficiently lock the fluid into a stable gel. This dual-material approach handles varying flow levels, providing reliable protection and maintaining a dry surface.
Understanding Additives and Alternatives
Some conventional sanitary pads may contain optional additives to enhance user experience. These can include fragrances, dyes, or odor neutralizers, incorporated into various layers of the pad. Fragrances and odor neutralizers mask menstrual odors, while dyes are for aesthetic purposes. These additives are not present in all conventional pads; their inclusion depends on product formulation.
Alternatives to conventional disposable pads focus on different material compositions. Organic and natural pads prioritize materials like organic cotton or bamboo across all layers, including the top sheet and absorbent core. These products avoid synthetic materials, fragrances, and dyes, catering to users who prefer fewer chemical additives and a natural feel.
Reusable cloth pads offer a sustainable alternative, designed to be washed and re-worn multiple times. These pads are constructed from multiple layers of absorbent fabrics like cotton, bamboo, or hemp, soft and highly absorbent. A waterproof layer, often made from PUL (polyurethane laminate), prevents leaks. They are secured to underwear with snaps rather than adhesive strips.