Cold brew concentrate disaster in my kitchen yesterday

I decided to try making my own cold brew concentrate for the first time. Followed a recipe that said 1 part coffee to 8 parts water and let it steep for 18 hours. Well I woke up at 3am to a loud crash in the kitchen. The mason jar I was using literally exploded from the pressure buildup, coffee grounds everywhere on my white tile floor. Took me an hour to clean up the mess at 3 in the morning. I learned that you need to leave way more headroom than you think, and probably use a proper cold brew pitcher with a spigot. Has anyone else had a jar explode on them like this?

2 comments

2 Comments

the_ryan1mo ago

And honestly that tracks because I've seen people online talk about doing cold brew in sealed jars and it's basically a science experiment waiting to go wrong lol. The CO2 from the coffee grounds has nowhere to go and builds up like a soda bottle left in the sun. I've used a french press with the plunger all the way up for years and never had an issue since there's that little gap for air to escape. Plus you can just press it down when it's done and pour straight out. Way less messy than mopping coffee off the floor at 3am.

knight.diana1mo ago

Honestly I gotta push back on this whole jar explosion thing. I've been making cold brew in mason jars for like 3 years now and never once had a pressure issue. The real problem is you used a sealed jar with no air escape. I leave the lid just barely cracked or use cheesecloth with a rubber band over the top, then after 18 hours I strain it through a regular coffee filter. No headroom problems, no 3am explosions. Your recipe sounds fine but that airtight seal is what got you.