[Homeroast] Vac Pot Volcanic Eruption WARNING!

Kirk Janowiak janomac at gmail.com
Mon Dec 21 15:11:27 CST 2009

I resemble that remark, Dave, although my MANY years includes just  
last year in the High School lab setting as a teacher.
Boiling "chips" (whether they be chips, beads, lozenges, or teflon  
"pills") are a standard bit of lab equipment in all science labs where  
boiling in glassware will be done, but only now do they seem to  
catching on in the kitchen. You can purchase boiling rings, disks, and  
"stones," from several kitchen/cooking/"gourmet" shops and online. The  
ones sold for kitchen use are "pretty," but porcelain chips (say, from  
a broken old teacup or saucer) work plenty well and will last for many  
years. I do prefer the lozenge-shaped ones made of borosilicate glass,  
as they are a little larger and easy to fish out of the pan when I am  

Even with boiling chips, I have had glassware "explode" when high-heat  
was applied. This could usually be traced to a few tiny scorings from  
prior cleaning or a scratch/nick on the very bottom of the boiling  
flask. Believe me when I tell you that I boil in "used" boiling flasks  
only after a thorough inspection!


On Dec 21, 2009, at 3:24 PM, Dave Huddle wrote:

> 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
> described.
> Dave
> 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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janomac at gmail.com

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