rubinken@Ken Hey Ken, if you put them on surfaces like tables, cardboard boxes, windows etc they'll be fine. If you put them on your forehead then the adhesiveness of it dramatically decreases (we tried this). You can lightly put a drop of water on the sticky attachers to remove any dirt/dust. While through testing we never reached a point where it was unusable because of use, you can use a piece of tape and it will work fine.