I’ll be discussing British pens in this context; finding flex nibs among American pens is different and I’ll leave that to someone else. Demand for flexible nibs never went away in Britain, and while there are many manufacturers who turned out firm-nibbed pens flex remained available until fountain pens began to go out of fashion in the mid-twentieth century. So there are plenty out there, but how do you find them?
I think the only way you can be sure that you get a pen with the degree of flexibility that you want is to look for sellers who provide writing samples, or who give a good description of the writing characteristics of the nib. That said, there are areas of pen production where you’re more likely to be successful. Old pens, for a start: most eyedropper fillers and very early lever-fillers are more likely than not to show an appreciable level of flexibility. Flexibility was expected in a pen in those days. That’s just how people wrote. This old Wyvern 14B eyedropper’s nib is one of the most flexible I’ve ever had.
Most Conway Stewart nibs (Duros excepted) are slightly flexible. Looking back over the records of the hundreds I have sold, perhaps two in every hundred Conway Stewarts are really flexible. This broad No36 and the fine 85L were exceptionally flexible. Looking at them, you might just have guessed that the broad might be flexible but the fine looks like any other Conway Stewart nib. Its appearance gives no clue to its performance.
That’s a large part of the problem: appearance is no guide to nib performance. You would expect that any nib with long, slender tines would naturally be flexible, and sometimes they are, but equally often they’re not. This beautiful Swan Minor nib gives little variation.
Counter-intuitively, those nibs with high shoulders and short tines are quite often super-flexes, like this Swan Minor No2 and this Leverless L205.
English Watermans of the nineteen-forties and fifties are about 50-50 flexible and firm. Most of those giving line variation are semi-flexible but some are really exceptional, like this 502.
As so many of the nineteen-thirties Watermans are of Canadian origin, it’s worth including them here. Many will have the flexibility you’re looking for, particularly the Waterman Junior, which is very often a full flex nib.
If you must have a flexible-nibbed pen – and their popularity seems to have taken off now – concentrate on the earlier pens, the Swans, the Blackbirds and the Watermans. Flex doesn’t always have to come at a high price, and many of these pens can be bought quite cheaply.