I use my dive slates and wetnotes on nearly every dive. For those of you unfamiliar with these extremely useful dive tools, dive slates (plastic tablets) and wetnotes (notebooks of waterproof paper) can be written on underwater and passed back and forth between divers. I use dive slates and wetnotes to communicate complex ideas with students underwater as well as to record survey data when I am exploring new caves. Writing on underwater writing utensils is just as easy as writing in dry air, but erasing the writing is not. Once a diver has written on his slates or wetnotes, how does he clean the writing off when he no longer needs it?
Before I met my current business partner, Dennis Weeks, I used a variety of methods to clean my dive slates. I never bothered to clean my wetnotes (as they had many pages), and instead either threw them away or stored them for posterity with my old dive masks and other dive gear. I attempted to erase my dive slates with standard pencil erasers, special gum art erasers, and various cleaning solvents. The erasers occasionally left a sticky goo on the slates. Neither method cleaned the slates completely; there was always a thin, grey layer of pencil or faint pencil lines left over once I was finished cleaning my slates. My methods worked, but they were not perfect.
My partner Dennis uses his slates and wetnotes at least as often as I do, yet I noticed his were always perfectly white! When I asked his how he cleaned his underwater writing tools, he showed me a small, dense white sponge. It was a Mr. Clean® Magic Eraser®.
Mr. Clean® Magic Erasers® were developed as tools for house cleaning, but they are also fantastic for cleaning both dive slate and wetnotes. Moisten the eraser slightly, and rub it gently across your underwater writing utensils to leave them looking like new.
I like to keep my eraser in a sealed plastic sandwich bag. I believe the erasers remain in better condition for a longer time this way. Another tip when using Mr. Clean® Magic Erasers® is to cut them into several smaller pieces. When carrying the erasers into harsh environments (such as on dive boats or jungle treks), they are likely to get salty or dirty. Cutting one large eraser into several smaller pieces allows a diver to get more use out of a single eraser. I like to cut mine into thirds.
The only drawback of Mr. Clean® Magic Erasers® is that they are so effective that they will also dull any permanent lines or marks that a diver may want to keep on his underwater writing tools. For example, I drew a grid using permanent marker on my cave survey slate. After a few uses of the eraser, the permanent marker lines began to fade and I had to redraw them.
Mr. Clean® Magic Erasers® last for months (if not years) of gentle use. I go through one every few months. The erasers are available at most supermarkets in the United States and Canada. Copycat cheap versions of the erasers have recently become available, but they do not appear to be as effective as the original version.
Every time a client asks me if there is anything I need from the States/Canada that I would like them to bring to me in Mexico, I check my stock of Mr. Clean®Magic Erasers® to make sure I have enough. I try to keep about five extra because I give them away to fellow dive guides whenever I see them attempting to clean a dive slate or wetnotes with another method. "Wow!" they exclaim as their slates turn white with just a few easy passes of the eraser, "It's like magic."