[Homeroast] Vac Pot Volcanic Eruption WARNING!

Dave Huddle 137trimethyl26dioxopurine at gmail.com
Mon Dec 21 14:24:01 CST 2009

MANY years ago, when I was in the chemistry lab, we always added a few
clean 'boiling stone' to a vessle of liquid that was going to be
heated to boiling.

Clean bits of broken porcelain work well because the irregular surface
encourages bubble formation, preventing the bumping behavior you

Westerville, OH

On Sat, Dec 19, 2009 at 1:40 PM, sci <scizen at gmail.com> wrote:
> By way of warning, and of curiosity, I need to tell/ask you what happened to
> my vacuum pot this morning. I have a Hario 5 cup tabletop model with a
> butane burner like those that SM sells. As usual, I poured 190f water into
> the bottom and put the moderately adjusted butane flame under it as I went
> about weighing and grinding some Nic. Paca. DP.
> After 3-4 minutes the water was not boiling. Odd. 5 minutes, no boil. Weird.
> Then around 6 minutes with absolutely no warning, no little outlier boiling
> bubbles, no slow ramping up to a boil, the whole bottom containter of water
> erupted like a Vesuvius, spewing water all the way to the ceiling!!! The
> explosion happened in a mere fraction of a second. BAM! Absolutely
> terrifying! It just went from a peaceful serene calm water state to
> EXPLOSION!! ??? *&% Fortunately I was alone and I didn't get burned. But I
> could easily be in ER right now with a scorched face.
> **So, please be warned vac pot users.**
> Also, does any science geek here know what caused this? BTW, the clean,
> bottom spherical glass was open at the top; nothing was obstructing it or
> creating pressure. Can you imagine what would have happened if I had the top
> sealed in place? I have never seen any open boiling pot, carafe, or whatever
> behave this way. I have used my much-loved Hario many times, but this is the
> first time this has happened. Since this is a tabletop model, meant for
> presentation of the process, I sometimes do this for friends. While I'm sure
> it would get a bunch of laughs if nobody got hurt, it would be a disaster if
> somebody did. I don't want it to happen again. Please CC any replies to my
> gmail address if possible.
> [My usual method when I get the best results has been to pour hot water in
> the bottom, get the water boiling with open bottom using burner, turn off
> heat, put the top part on, relight flame, watch water travel to the top,
> pour coffee, stir, reduce heat, wait 2-3 minutes, cut heat, watch draw down,
> drink. This may not be the best method now, but I'm nearly certain I learned
> it here.]
> Have a wonderful day!
> Ivan
> the "coffee animal"
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