From what I remember re:clothespins.. Of course, they are made of wood. Wood is porous and will pick up water and any chemicals which may be hanging around. Also, from my experience using clothespins, they do stick. Like I said before, I use zinc coated bulldog clips, you can get them at any office store. My "method" is to make a loop with a rubber band around the hole in the bulldog clip, then make another loop around the shower rod, I hang my processed film there to dry then if anything drips off, it will drip into the bathtub, fire up the shower and wash it down the drain.