I grew up with a milk allergy, and so use a milk substitute on my cereal. It comes as a concentrate, which I dilute with water. I had been using plastic pitchers, but have been wanting to switch to glass. However, the marks I put on the glass with a "permanent" marker to indicate how much water to add, and how much to use for one bowl of cereal so I don't get too much or too little for the last bowl, kept washing off.
So I bought some "Armour Etch" at the craft store, opened windows and donned gloves... and now I have pretty stripes to mark everything! :)
I marked my juice pitcher too, so that I don't have to worry about what's dirty or clean, and can just use what's available.
I hope those rinsed-off chemicals don't cause any environmental problems downstream. :(