Bang! And the ink… well, in general, was not gone, really. Waterman Black and Viva black, neither of which claim to be unusually permanent, were affected. The Waterman Black faded quite a lot and turned blue; it does this when exposed to water as well, though less than that. It has not vanished but has definitely moved from “readable” to “possibly decipherable”.

The Viva ink I bought in a pack of fifty short international cartridges from a branch of Rymans, for just over a pound. It is made in Slovenia by a company called Vivapen, and is actually really good ink – nice dense colour to it, as you can see quite permanent, and for just over 2p a cartridge one can’t go wrong. (I have a suspicion that they make ink for other companies as well which is rebranded.) It just turned green and faded a bit – more durable than the Waterman certainly.

The others really didn’t care in the slightest about being bleached. The two Noodler’s inks at the bottom were ever so slightly paler at the end; the Sharpie marker had spread slightly on the paper; the Sailor Kiwa-Guro “nanocarbon” ink was entirely unaffected. Also note that whatever ink they use to mark the grid on Rhodia pads also didn’t care.

In fact, really, this was one of the more boring experiments that I have done. Sorry. The only thing that’s been learnt here is that Waterman Black is not bulletproof but doesn’t claim to be, and that a Slovenian ink that you’ve likely never heard of is quite durable. Next time I will try concentrated sulphuric acid or a laser or exposure to Martian polar winds.

In order, we have:

• Diamine Grey. Slightly water-resistant, in that it is visible afterwards and almost readable, but not pretty.

• Sailor Sei-Boku – the greenish blue “nanocarbon” Sailor ink. As befits an ink by a company called “Sailor” this ink remains identical no matter how much it is dunked into water. Sei-Boku is termed “archival quality” so really should be able to cope with being dunked in a sink.

• Waterman South Seas Blue, which is really a turquoise. Here we see the difference between a sailor and the sea. South Seas Blue, when exposed to water, is overjoyed and leaps off the page in ecstasy, to join its brother and sister molecules.

• A black Sharpie marker which I happened to have lying around. No nonsense here. Water? Why should it care about water? Try bleach or napalm to erase this sort of thing.

• Diamine Monaco Red which surprised me a little (though Diamine inks are not noted for water resistance generally). Monaco Red just vanishes with barely a trace. I’ll grant that that example of Monaco Red was likely contaminated with a lot of J Herbin Rouge Caroubier, since it normally dries to a brownish “there’s been a murder sir” colour, but even so… evidence has been eradicated.

• And then I had run out of inked pens so decided to try a pencil, specifically a 3B lead in a Caran d’Ache clutch pencil. Pencils have something of a reputation (in my mind anyway) for being impermanent, given that they can be erased with a piece of rubber, but graphite particles embedded into the surface layer of paper are apparently entirely non-bothered by the presence of water.