Why do I slide the 'F' instead of signing it twice?
In ASL, sliding or slightly bouncing a handshape is the standard way to indicate a double letter. It makes fingerspelling much smoother, faster, and easier to read than forming the exact same letter twice in a row.
Can I use this sign for turning off an electronic device?
Yes, fingerspelling O-F-F is very commonly used to indicate that an electronic device, like a light switch, computer, or television, is powered down.
Should I mouth the word 'off' while signing it?
It is common to mouth the word 'off' naturally while fingerspelling it, especially since it functions as a lexicalized sign—a fingerspelled word that is treated like a single, unified vocabulary word.