Yes , they do lose effectiveness with use . The carbon is in loose form and washes away gradually as the suit gets rinsed out . I buy one set for each season that I intend to hunt . I generally rinse them out 2 or 3 times per season . An alternative that you may wish to explore is a leaf cut ghillie suit to go over the carbon suit . These are usually mesh suits with patches of leaf cut fabric sewn on . They are light , cool , and would provide excellent concealment over the OD . Sportsmans Guide carries these for around $80 , and you only have to buy it once . [8D] I have one and love it when the temps climb unexpectedly . They' re great for squirrel season too , you can wear light camo or even just green clothing under them .