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#1
Old 06-03-2014, 05:47 PM
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Can I heat a Pyrex beaker (600 mL) on a stove top?

I usually use a microwave but I don't have access to one now and I need to heat up some solution for research. I just need to bring the solution to a slow boil, will the heat from the stove be too much for the beaker though?
#2
Old 06-03-2014, 05:49 PM
Nope! I said stop!
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Originally Posted by EndlessEntropy View Post
I usually use a microwave but I don't have access to one now and I need to heat up some solution for research. I just need to bring the solution to a slow boil, will the heat from the stove be too much for the beaker though?
I use laboratory grade Pyrex beakers on hot plates or over Bunsen burners to boil water. If it's lab grade and Pyrex it should be ok.
#3
Old 06-03-2014, 05:55 PM
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if your stove top can spread the heat like a hot plate or a flame spreader then it might be OK. if not then good to use a heat spreader of flame spreader. for laboratory Pyrex.
#4
Old 06-03-2014, 08:43 PM
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Originally Posted by johnpost View Post
if your stove top can spread the heat like a hot plate or a flame spreader then it might be OK. if not then good to use a heat spreader of flame spreader. for laboratory Pyrex.
It'd probably be enough to put it in a frying pan to get even heating. I wouldn't want to try to heat on an electric coil.
#5
Old 06-03-2014, 10:08 PM
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I recommend against using an acetylene torch aimed at one spot.
#6
Old 06-04-2014, 09:50 AM
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By "stove top" do you mean a gas stove or a ceramic hob? A ceramic hob ought to be fine for a proper Pyrex beaker, but I wouldn't put one directly on an actual flame.
#7
Old 06-04-2014, 10:12 AM
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With Pyrex you need to avoid creating hot spots.
Use a mesh screen or pan to spread the heat evenly over the bottow of the beaker.
#8
Old 06-04-2014, 10:20 AM
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Can you use a double boiler? Boil water in a pan -- put the Pyrex in that.
#9
Old 06-04-2014, 10:36 AM
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I doubt that you will have a problem. For years, I used a Pyrex coffee pot directly on both electric and gas burners. I also heated Pyrex beakers directly over Bunsen burners and on electric hot plates in my lab.
#10
Old 06-04-2014, 02:45 PM
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Originally Posted by jasg View Post
I doubt that you will have a problem. For years, I used a Pyrex coffee pot directly on both electric and gas burners. I also heated Pyrex beakers directly over Bunsen burners and on electric hot plates in my lab.


This is what my sister does to this day. For over 20 years she has been doing this. No breakage so far. Her coffee pot is at least 15 years old and used daily.
#11
Old 03-13-2016, 10:08 PM
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So as you say the fire not directly on the pyrex item; may you heat a beaker or a round flask at 350C with a fire and an asbestos mesh to perform a distillation?
#12
Old 03-15-2016, 05:38 AM
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I would say be very careful. Pyrex sold in the United States after 1998 is an entirely different compound than Pyrex sold prior to that.

Now, Pyrex uses thick, but plain tempered glass under the brand name Pyrex.
Prior to 1998 (in the US) Pyrex was made of borosilicate glass, which is far better suited to withstand high temperatures and isolated hot spots.

The old coffee pot mentioned in this thread is most likely the borosilicate compound glass. I broke a standard Pyrex 2.5 glass measuring cup by heating some liquid on an electric stove.
#13
Old 03-15-2016, 08:30 AM
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Pyrex labware is still proper borosilicate glass, and I'm pretty sure there's no such thing as a tempered glass "beaker" or "round flask".

IME it's perfectly safe to boil something very vigorously in a pyrex beaker on a hot plate. Additionally, those ceramic hot plates aren't always flat, so there's effectively a very small contact area between it and the glass.

On the other hand, I have managed to destroy a few pyrex beakers and bottles through particularly clever combinations of extreme thermal shocks, pressure, and physical impacts.
#14
Old 03-15-2016, 04:02 PM
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Originally Posted by lazybratsche View Post
On the other hand, I have managed to destroy a few pyrex beakers and bottles through particularly clever combinations of extreme thermal shocks, pressure, and physical impacts.
You need all three? I'm quite adept at breaking glass with just physical impacts.
#15
Old 05-11-2016, 11:50 AM
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The STRAIGHT DOPE

RE: "Prior to 1998 (in the US) Pyrex was made of borosilicate glass...."


Listen, all this information can be found in less than TEN minutes.


PYREX is a brand name for Corning CO. manufactured BOROSILICATE glass. They STILL manufacture it, for LABORATORY USE.


Yes, Corning "spun off" it's "pyrex" KITCHENWARE division in the late 1990s. Yes, it's NOT made in America. However, this is "world kitchen" now trademarked with LOWER CASE spelling "pyrex". You can tell the difference by p y r e x being in LOWER CASE on this KITCHENWARE as well as the "glass" having a BLUE tint, which belies that it is indeed SODA ASH glass.

Now, Corning STILL produces LABORATORY PYREX. That's UPPER CASE "PYREX" for use in scientific laboratories. In fact, they produce at least three different types, as well as something called VICOR,which is 96% silica glass.

So, IF you have "vintage" or whatever pre-1990s kitchenware PYREX, yea, go head and do what you want or have always done with it. Personally, I wouldn't put it DIRECTLY on a burner or electric stove heating source. Glass loses strength over time so you're tempting fate.

So, "Pyrex sold in the United States after 1998 is an entirely different compound than Pyrex sold prior to that." is sort of true, BUT only when referring to KITCHENWARE.

And "Now, Pyrex uses thick, but plain tempered glass under the brand name Pyrex." is also sort of true. spelled pyrex (LOWER CASE) it's soda ash glass. If you find a measuring cup or dish with it spelled in UPPER CASE, than it's BOROSILICATE glass, the stuff for which everyone knows as "PYREX" but a brand name for borosilicate glass manufactured by The Corning Corporation, Corning NY. USA.

Last edited by MattyM; 05-11-2016 at 11:55 AM.
#16
Old 05-11-2016, 12:02 PM
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Heh. I've read that old school PYREX measuring cups and dishes are in high demand at yard sales for certain drug cooking operations.
#17
Old 05-11-2016, 08:18 PM
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So, there's a difference now between "pyrex" and :::PYREX::: of the family CORNING?

Last edited by Senegoid; 05-11-2016 at 08:18 PM.
#18
Old 05-11-2016, 09:07 PM
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One can use regular glass on a stove top ... just heat it slowly ... if the whole container stays about the same temperature, there's no stress to fracture it ... with pyrex you can heat quicker, and a double boiler would be slow enough for pyrex.

Last edited by watchwolf49; 05-11-2016 at 09:07 PM. Reason: ... very slowly ...
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