[Homeroast] Vac. pot seal breaking problem

Rich rich-mail at octoxol.com
Sun Jun 6 00:51:58 CDT 2010


They are called sites of nucleation and promote nucleate boiling. 
Nicking the glass with a file is a good way to induce a serious stress 
riser and have the pot shatter in your face.  Scratched lab ware goes 
immediately in the trash.  Put a couple of lab boiling stones in the pot 
until it has been used enough to get some natural roughness.  Can't find 
any lab stones at the second hand store?  A couple of glass marbles will 
work also.  This is why the filter cloth with the chain was popular back 
in the day.  The chain prevents this little eruption.  Having the coffee 
pot explode on the stove is not the way to start the morning.

sci wrote:
> I have been waiting until all the liquid goes south to the bottom and
> there's a bubbling and sucking sound. So I'm assuming the vacuum has
> equalized with ambient air pressure. The problem is that the rubber is very
> "grippy." It's pretty new. I don't press it hard into the bottom, but just
> gently place it there with a tiny downward pressure. I think the suction
> draws it a bit deeper. The best solution so far has been the lubricant . I
> found some food grade silicone lubricant and used the tiniest amount
> possible on the rubber. Vasoline would do the same. The seal breaks easier
> now.
> 
>  On a different note, another fine point  I've learned  for the vac. pot
> afficionados, The same unit did a super-heated flash boilover that literally
> exploded and spewed super-heated water out the bottom chamber like a
> volcano. It scared the ever-living daylights out of me because I had been
> peering over the top during earlier uses. Nowhere in the instructions, or in
> anything on anybody's website, including SM, have I ever seen a warning
> about this phenomena, but it is extraordinarily dangerous and could result
> in a severe accident. It could happen to any unit.  It turns out that the
> perfectly spherical lab glass in a perfectly clean state provided no place
> for "boil generation spots." To fix this, take a diamond file and make some
> scratches on the bottom inside of the bottom chamber. These scratches
> provide imperfections where little steam bubbles can easily form and start
> the boil. Otherwise, a super-heating event could occur. ---just saying, I'd
> hate somebody to live with third degree burns on their face.
> 
> Ivan
> 
> 
> Date: Wed, 2 Jun 2010 21:22:32 -0400
> From: "John Borella" <jborella at ct.metrocast.net>
> To: "A list to discuss home coffee roasting. There are rules for
>        thislist,       available at
> http://www.sweetmarias.com/maillistinfo.html"
>        <homeroast at lists.sweetmariascoffee.com>
> Subject: Re: [Homeroast] Vac. pot seal breaking problem
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> Are you waiting for the vacuum to break before you try to remove the upper
> globe? I use a 5C Hario V/P every morning & have no problem removing the top
> portion by tipping it to the side & lifting it out.
> 
> John B.
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