The (Apparent) Importance Of Coffee Lids

I’m a coffee fan and since my wife and I purchased a Breville Barista Touch Impress for ourselves Christmas of 2023. We’ve been making espresso-based drinks at home nearly every day. It’s straightforward to use, has a built in tamper, has auto milk foaming, but can also run in manual mode.

I take a latte, cappucino, or flat white to work with me in the morning using either my Hydroflask or Corksickle travel mugs but one time I was in dire need of a mug and just snagged a regular old pint sized glass and took it with me.


My commute to work is only 3.5 minutes (without a train) and traveling with a coffee in my hand and manually stabilizing it seems to work just fine.

When I took an open-top glass I realized that I normally drink the coffee goodness well before it get’s meaningfully cold. Often, I’m polishing off the last dreggs soon after daily standup meetings (approx 8:45). This quick consumption means that heat loss isn’t too much of a worry, I’m plenty used to coffee cooling down in to-go cups and it didn’t seem much different.

So, I switched to just pouring my drinks into one of the same travel mugs and leaving the lid at home. I was coordinated enough not to spill, drank the coffee before it got cold, and had one less part to clean.

I started noticing something: the foam would dry up along the side of the mug as I drank it. I considered this a draw back to drinking coffee in the winter since a coffee cup does the same thing with a good cappucino in it.

A coffee travel mug with some great milk foam accumulating on the side!

But, this last week I decided I’d like some warmer-than-normal coffee and what did I find…

A coffee travel mug with no foam accumulation on the side.

Not only that, but the condensation on the lit pointed me to a revelation: The lid is useful not only because it keeps the coffee inside, it also maintains a humid environment which either makes it slipperier or less likely that the foam will condense/dry on the walls of the mug.

Water condensation on the lid points to a theory.

Further investigation is required, maybe a humidity chamber for an open top mug while it’s not being drunk.

Thanks for reading! Facts and circumstances may have changed since the publication of this post so it's worth checking for new posts to see if anything's changed before jumping to conclusions.

Have a question or idea? Shoot me an email at _@chip.bz or ping me on mastodon at talking.dev/@chip.