Do you ever want to pretend to be a spy sending hidden messages? While we’re not going to be sending hidden messages revealed by catalysts like lemon juice and heat anytime soon, they’re not completely off the table either.

iMessage offers a fun way to send hidden messages to other iMessage users. It’s a great way to mess around with your friends. But when you do want to send a sensitive message that nosy people don’t “accidentally” see, it’s got your back. The receiver would definitely sense something’s up and would reveal the message away from prying eyes.

Sending a message with invisible ink is pretty easy but there’s a one hundred percent chance you might have missed it. It’s a little hidden along with some other cool iMessage bubble and full-screen effects.

Once you’ve typed the message or even added a photo or video to the message box, tap and hold the ‘Send’ arrow.

The ‘Send with effect’ screen will appear. Tapp the ‘dot’ next to ‘Invisible ink’.

The send arrow would shift there and you’ll also see the preview of what the message will actually look like with invisible ink. Tap the arrow to send the message with invisible ink. To return to your message without using the effect, tap the ‘x’ icon.

The message will appear in the conversation on both ends with a shimmery animation, hiding the actual contents of it.

To read a message with invisible ink, the recipient has to swipe across the full message to reveal it. Tapping along parts of it only reveals the message partially. When you swipe up or down on the screen, i.e., the message goes out of view once, it returns to its hidden state.

Keep in mind that the effect only works for other iMessage users. When you’re messaging non-Apple users, you can still the message with the effect from your end. But they would only receive the message with an additional annotation that says “Sent with invisible ink”.

Of course, the effect is just a fun little effect and in no way a fool-proof way to send secret messages. Anyone can swipe across the message to reveal its contents. So, you might want to refrain from sending any sensitive messages you really do want to keep secret.