I was born and raised in the mid-Atlantic region on the US east coast. The weather forecast from June to late September is always “Hot, Hazy, and Humid.” The heat and humidity are so bad even weeds beg for someone to put them out of their misery. The tar bubbles up from the asphalt, and the creosote leaks out of the telephone poles. It is gross, the world is sticky and gummed up. This being the dog days of summer, a thought occurred to me, how does heat and humidity impact fountain pens?
Welp, I wish I found a definitive answer, instead I found a series of diverse thought-provoking prose. My initial thoughts about the impact heat and humidity have on pens and ink were in error. My assumptions were based on the popularity of eyedropper-style fountain pens in tropical and subtropical countries, such as India. Turns out the popularity is related to the heat and humidity – they accelerate the decomposition of the ink sac – duh, my bad. Cartridge and converter pens don’t suffer from this issue, but they hold very little ink in comparison to an Airmail which holds a small ocean of ink.
Humidity is moisture in the air. When the humidity is higher there is less room for additional moisture resulting in less evaporation directly impacting ink drying time.
Alternatively, paper is hygroscopic (water absorbing) and will absorb the moisture from the air. Humidity and changes in temperature can influence a paper’s weight, thickness, and rigidity. Ink viscosity increases at lower temperatures, which can restrict ink flow and density. While at high temperatures, ink viscosity decreases. Ink being primarily water contains humectants and variable viscosity associated with temperature might exacerbate things. Humectants are hygroscopic stuff that promotes the retention of moisture in water-based inks and paints.
Temperature primarily impacts viscosity but may cause the air in the pen ink reservoir to expand or contract thus impacting the ink flow. It is true that capillary action is greater at higher temperatures, but should be negatively impacted by high humidity and the hygroscopic properties of the paper. I read comments on FPN and Reddit, and contributors mention their ink color seems more saturated in the dry summer heat. Is this the result of greater capillary action or dye inks with greater color saturation?
The bottom line is this, Heat and Humidity will make your pen write drier or wetter based on these conditions, and the hygroscopic properties of your paper. They are bad for ink sacs thus causing issues for vintage pen owners. I know, Duh! Oh yeah, Hazy, has no impact on the function of your pen or the ink but it will result in respiratory conditions so stay inside, and enjoy the AC (airco) on those ozone alert days.COPYRIGHT © 2021-2022 DANNY WATTS and CHRONICLES OF A FOUTAIN PEN.