There are a number of ways that you can clean a slate, some are more practical than others. Here are some of the ways that I’ve tried to clean my slates:
Magic Erasers / Melamine sponge (Recommended)
These sponges are hands down the best thing to clean a slate with. They work wet or dry and can be easily carried around in a bag or your BCD. Not only are they convenient but do a fantastic job of cleaning a slate, removing pencil marks with a minimum amount of scrubbing.
If you’re interested, here’s how they work https://home.howstuffworks.com/magic-eraser.htm
Pencil Eraser
A normal run of the mill pencil eraser works well for cleaning your slate but can leave some dark smudges on your slate as it spreads the graphite around on the slate. In addition, it also leaves you with eraser rubbings, which I don’t like because they create a mess.
The bottom of a flip flop or a bit of rubber foam
In a pinch, the bottom of a flip flop or a bit of rubber foam does a great job of cleaning your slate. It’s a great trick rather than trying to rub it out with your finger, and a lot more efficient.
Jif
This is great when you’re at home and you’ve got a bit of time. If your slate is somewhat grey, it’s a great way of restoring the colour. It gives it a little bit of extra life.
Your finger and some elbow grease
When you really have no other option, then rubbing with your finger will usually get your pencil markings off but it will leave your slate looking grey until you can clean it properly
Conclusion
I usually carry around a magic eraser in my spares kit so that I can clean my slates, they come in really handy and are a great addition to your kit.