cillit bang vs ink
Inspired by a post on FountainPenNetwork where somebody had exposed a number of different inks to not only water, but bleach, I decided to do something similar with a selection of the black inks that I possess (and also Noodler's El Lawrence, which is "dirty pond algae" coloured rather than black) some of which claimed to be "archival", "bulletproof" and similarly impressive things. Would they turn out to flee at the hint of strong alkalis? To test, I wrote the same things on two sides of a piece of paper, cut the paper in half, put one half in the sink and sprayed it repeatedly with Cillit Bang over a period of fifteen or twenty minutes.
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.