Permethrin is a synthetic insecticide derived from chrysanthemums, widely used to treat clothing and outdoor gear for personal insect protection. Unlike repellents applied directly to the skin, permethrin bonds to fabric fibers, acting as a contact insecticide and repellent. It causes insects like ticks, mosquitoes, and chiggers to become disoriented or die upon exposure. This treatment creates an invisible barrier on clothing, significantly reducing the risk of insect-borne diseases without requiring the chemical to be absorbed by the wearer’s skin. The process of applying permethrin to clothing at home requires careful attention to safety and application technique.
Essential Safety and Preparation Steps
Reviewing the manufacturer’s label is mandatory before starting, as instructions for this regulated pesticide vary between products. The application must be performed in an area with excellent ventilation, ideally outdoors and away from wind, to avoid inhaling the chemical. If working in a garage or similar space, ensure the area is fully open to the outside air.
Personal protective equipment is necessary when handling the product, especially concentrated formulas. Wear chemical-resistant gloves to prevent skin contact. Consider eye protection and a mask to minimize exposure to fumes or spray droplets. Lay down a plastic sheet or drop cloth to protect the ground surface from spills or overspray.
A severe warning concerns household pets, particularly cats, for whom permethrin is highly toxic when wet. Cats lack the specific liver enzymes needed to metabolize the chemical, making even small amounts dangerous to their central nervous system. All cats must be kept completely away from the application area and the treated clothing until it is fully cured and dry.
Permethrin forms a strong bond with both synthetic and natural fibers, including cotton, nylon, and polyester. Most products are formulated to be effective on a wide range of textiles without causing damage.
Detailed Application: Spray vs. Soak Methods
The two primary methods for home application are using a pre-diluted spray or a concentrated solution for soaking, depending on the volume of clothing to be treated. Ready-to-use spray products typically contain a 0.5% permethrin solution and are the most convenient option for treating a few items of clothing or gear.
For the spray method, hang the garment on a clothesline or lay it flat on the protected surface, holding the can six to eight inches away. Apply the spray evenly with a slow, sweeping motion, covering the entire surface until the fabric is damp but not dripping excessively. Treat both the inside and outside of the garment, paying close attention to areas where insects are likely to crawl, such as cuffs, collars, waistbands, and seams. One 6-ounce bottle of spray is typically sufficient to treat one full outfit.
The soak method is more economical for treating a large quantity of clothing. It involves diluting a permethrin concentrate, often 10% or higher, to the recommended 0.5% final solution. For example, a 10% concentrate requires mixing one part concentrate with 19 parts water. Follow the manufacturer’s instructions precisely to ensure the correct concentration, as using a solution that is too strong can be hazardous.
Submerge the clothing fully into the diluted solution in a non-absorbent container, such as a large bucket or plastic bin. Allow it to soak for the time specified on the label, which is often a few hours or overnight. After soaking, remove the items and gently wring them out to conserve the remaining solution. Dispose of the remaining solution properly according to local regulations and product instructions; never pour it down a drain. Soaking achieves a uniform saturation of the fabric fibers more thoroughly than spraying.
Curing, Maintenance, and Treatment Duration
The treated garments must be allowed to air dry completely before being worn or brought indoors. This drying period, known as curing, is essential because it allows the permethrin to bond securely to the fabric fibers. Curing can take between two and four hours, or longer depending on humidity. The fabric must be dry to the touch, and the chemical’s odor should be negligible before the clothing is considered safe for skin contact.
Home-treated clothing typically retains effectiveness for up to six weeks or through approximately six wash cycles. The insecticidal property of permethrin is not diminished by short-term exposure to water or sweat, but the mechanical agitation of a washing machine gradually removes the chemical.
To maximize the treatment’s life, wash the clothing using a normal cycle with regular detergent. Dry cleaning should be avoided as the chemicals involved can strip the permethrin from the fabric. While it is not necessary to wash treated clothing separately, avoiding fabric softeners is recommended. Air-drying in the shade can help prolong the treatment by reducing exposure to ultraviolet light, which causes the chemical to break down over time. Once fully dry, the permethrin is fixed to the clothing, making the garments safe for wear.