Hello group
For 40 years or so I have been lettering my projects with india ink and protecting it with "clear nail polish" the best of these by far is HARD AS NAILS be sure to get clear not tinted. Part of the charm is the convenience since it includes a brush - just reach for the bottle at the back of the bench. One cravat - it is a good solvent and can only be used on water based printing, like the india ink pen from the art store. If you use it on a Sharpie there are smudging problems unless you are very fast. In more recent years I have largely switched to using labels made in a MS Word table. Word allows the table cell dimensions to be set precisely so its easy to cut the labels to the desired dimensions. For a terminal strip you adjust the pitch of the legends to match the terminal pitch then one long label does the whole strip. If using paper for the label base I glue it on with an Elmers glue stick and coat the label with the hard as nails. While at the art store look at the paint pens, the paint is acrylic and also works well with the hard as nails, comes in numerous colors that are opaque. As in white lettering for a black knob.
If you really want a first class protectant go with a UV-cured-resin "pen" sold under the name LAZER BOND . Tough and quick. Shop it, the price varies widely.
Eric WB6KCN
Eric Schumacher