Posted in Ink, Pens

Hot, Hazy, and Humid; Their Effect on Pens and Ink

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.



I'm a loser as my wife likes to tell me, I enjoy researching dead cousins and playing with fountain pens.

15 thoughts on “Hot, Hazy, and Humid; Their Effect on Pens and Ink

  1. Very interesting post. Here in Wales we are very well known for having rain. Lots of it. How Green is Wales? If you start a Google search with that question. It does not talk of the colours of the valleys. More about ethical ecological considerations. Here in your blog you speak of heat and humidity and now, in these changing times, we are getting extraordinary weather. Very much like your own described experiences. Not quite oozing tarmac and creosote, but very, very uncomfortable outside. I shall look at my pen, ink and paper outcomes now. Especially as I intend to write outside in the fresh air! See if any changes, like the ones you describe, are noticeable. Interestingly. The dehumidifier out in our long and narrow back storage room has to be emptied twice a day currently. 4 litres total. That’s quite a bit of moisture hanging about. Good to see rooms dry though. So maybe my enjoyment in vintage pens and wet ink writing is performed in a more balanced atmosphere here in the house. Cheers Danny. Great read as always.

    Liked by 1 person

    1. I’ve had my notebooks swell with the absorb moisture. At the time my pen of choice was a Pilot G2 which normally handled the pages in their bloated condition. Occasionally it would ripe holes. We moved to Colorado which is a semi-arid environment. In a typical year we may see 16 inches of rain, 50+ in snow. Green is not in our vernacular. Thanks for commenting.

      Liked by 1 person

    1. Thank you for visiting and the comment. I have many vintage pens and they act funny as the weather changes. The contemporary ones are well behaved but I’m sure some have issues I’ve just never noticed.

      Liked by 1 person

      1. I’ve always wanted to use fountain pens. I think I haven’t, because I don’t know much about them. Although with ink cartridges it’s easy to change the cartridge and not make a mess, right. I’m going to Follow you, get inspired and FINALLY start writing with one. Are you an illustrator? I ask, because I’m working on some children’s books and I like your Gravitar (I think that’s what you call it.)

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      2. Ink cartridges are simple and least likely to make a mess. A major advantage to FP is the vast options when it comes to ink colors. They are easier to write with, your hand is less likely to tire. I did a series of FP primers at the beginning of the year. Since you are intrigued might I suggest reviewing them prior to a purchase.

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      3. Of course, do you mean on your blog post, you’ve done reviews? Have you posted a video on how you do the entire process, dipping ink, what to be careful about, so we don’t make a mess? I would imagine the ink stains your fingers… NOW, thinking of Ebenezer Scrooge when he is doing his accounting books, beginning of movie. Also, thinking of The Scarlet Pimpernel, he would write messages and then use his rose wax seal to close the envelope. Years ago, my daughters did buy me a red feathered quill. You can see post/picture of it. Maybe it’s time to finally give it a try.


      4. Are the Primers at the beginning of your Blog? Is that what you mean? Have you ever done a video, showing us how to do this process, so we don’t make a mess with the ink? I’d have to Youtube this. I’m sure beginners are messy. Sort of like painting a room, seems easy, but surprisingly when we are inexperienced, all sorts of messy things happen. :). CURIOUS, do you use the FP all the time in place of a normal pen?

        Liked by 1 person

      5. The primers began on mid-January (there are 4). Sorry no videos. I use a FP exclusively and have since 2007ish. I have many. There are 4 inked up today with 4 different colors with 4 different nibs (controls the width of the line the pen makes).

        Liked by 1 person

  2. Hm, I wonder if that’s the reason why so many people say the G2 is the best gel pen but I find it lacking. Maybe it’s the high humidity here that’s screwing up the reviews. I’ve never known anything else except humidity though, so I’d be interested in how my pens would write in drier weather.

    Liked by 1 person

    1. I used to only know humidity, I moved. Now the average humidity is only 20%. My skin dries out, I get a dry cough, and sinus issues. Since Covid, everyone looks at me like I’m diseased. BUT, it beats the humidity.


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