In my experiment, I compared how much bacteria was present on sponges, dishcloths, and dish mops. The dishcloths (folded) and dish mops had the largest surface area to trap food particles and to retain moisture. The sponges were porous and dried faster. Since bacteria grow fastest in warm, moist environments, the sponges retained the least bacteria. All of the cleaning materials had much more bacteria present after being stored for 48 hours. This is because the materials were stored while still very wet and still had food particles in them, especially the folded dishcloths and dish mops. The amount of bacteria could have been reduced by wringing the materials and spreading them out to dry after each use.
There was also a difference in the results obtained for the "3M antimicrobial sponges" and the regular sponges. The 3M sponges have an antimicrobial agent (consisting of a number of combined ingredients) embedded into the cellulose fibers when it is still in a liquid state. The cellulose is then "cooked" into a solid state that looks like a sponge. The antimicrobial agent lasts as long as the sponge does, and will not rinse out. It does not remove bacteria from surfaces, but instead it does not allow bacteria to grow inside the actual sponge. This is why the antimicrobial sponges had much less bacterial growth than the regular sponges.
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