Those Tiny Holes In Pen Caps

[rwilsonedn]

I have wondered for years about those little holes. I'd never heard an explanation that I really liked. Some say that the holes are to comply with a government safety regulation to prevent infants from partially swallowing the cap and suffocating. But that didn't seem physically plausible, and anyway I have seen holes drilled in caps that dated from long before the arrival of safety regulations. And I've heard that the holes are to equalize pressure when you remove the cap, so that the reduced pressure doesn't draw ink out of the feed. But that also seemed physically implausible: leakage through the cap threads could equalize pressure quite sufficiently. And the final end of that explanation was when I found a turn-of-the-century portable dip pen with a hole in the cap. No feed, no ink to draw out. So what is the origin of the hole?

Yesterday I received a possible clue. I came into possession, thanks to a wonderful seller, of a pristine Bayard chased BHR lever-filler with an intact box and instruction sheet. The sheet was in French, of course, but Google translate managed to decipher the first page, which covers maintenance of the little holes in the cap. Among other things, it says:

"... those aeration holes avoid any condensation of water vapor that might dilute the ink on the end of the pen." So at least that is one early and respected pen manufacturer's explanation.

This might also explain how the stress-relief drilling on nibs came to be called "breather" holes, even though they have nothing to do with air flow. Breather is another possible translation of the French word that Google rendered as aeration. Could it be that as time passed and original documents were lost, people began to confuse the breather holes in the cap with the stress-relief hole in the nib?

ron

 

[jar]

Not sure about the two getting confused but the holes in the cap served several functions. In early pens it equalized the pressure in the cap and body so ink was not forced into the cap when local air pressure increased. It also could act as mentioned but in very high humidity areas had the opposite result.

[Yehenara]

IIRC they allow the equalisation of air pressure, or something like that.

[richardandtracy]

When I've made transparent caps without air holes, I have seen ink pulled out of the pen as the cap is removed. There is usually a secondary seal at about the end of the section that remains fairly well sealed as the cap goes on & comes off. The cross sectional area for the air to fill the void can be very small (much smaller than that of the small hole), leading to a high pressure differential when the cap is removed. The pressure in the ink chamber will be at or near atmospheric pressure, so some ink is squirted into the cap. When I drilled a hole, this effect didn't come into play again until much higher cap removal speeds - in fact it was very difficult to replicate it.

 

Regards,

 

Richard.

[Sasha Royale]

Ink weavels.

[Sandy1]

Portal for Ink Putti

[Namru]

So when uncapped it doesn't pull a vacuum, which is more useful with pens with a malleable ink chamber.