Seeing that my collection of VFTs is ever expanding, I've been meaning to put labels on their pots to better keeping track of them. *Initially, I had planned on just writing their info on some masking tape and then overlay some clear packaging tape so the masking tape won't get wet - but part of the clear packaging tape will be down in their water trays. *
Would the tape somehow leak some kind of pollutant(s) into the water that could harm my plants, or am I just being paranoid?
Well there is a problem with this, but it is not about poisoning your plants, but rather losing the ID. Your plan will not work. Water will get under the tape and diffuse the ink, it will blurr and fade. Even laundry markers (sharpies) are too temporary.
The best plan is to write the name on a white plastic marker with a soft lead pencil. If you dont like the markers showing, then make them small enough to insert beneath the medium. The lead will repel water and not wear off. Actually, burying the markers might be the more secure way: this way they can't be blown or PECKED out of the pots. Ink just doesn't cut it for labels, unless it is India Ink.