The Fresh Loaf

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MERCURY an thermometers need advice

vince hav's picture
vince hav

MERCURY an thermometers need advice

while cooking chicken strips in 350+ degree oil in cast iron dutch oven i notice the candy thermometer that i was useing for oil temp didnt look right...i pulled it out and the bulb had broken....i assume it has mercury in it tho it the liquid is blue...i of course threw it all out an cleaned my dutch oven with dawn dish washing liquid a couple of times...i then dried it out good with a paper towel and appled new oil and finished cooking....i was then told by a friend on fb that my dutch oven may not be any good and that i probly shoud throw it away....

!. do the candy thermometers have mercury in it or is it some other liquid that is safer?

2. will i hav to throw out my cast iron dutch oven? its not the porcelin coated on the inside and out kind its the black oven sold at walmart in camping section 

any help appriciated


ZD's picture

Mercury is very dangerous, but the good news is that it is not blue. Mercury is shiny like a mirror. You have already cleaned you dutch oven so you are good to use it.

Greg R

LindyD's picture

Hi Vince,

Did the thermometer a silver bulb?  If the bulb was any other color, it didn't contain mercury.

Mercury is not blue.  It is silver and breaks into tiny balls that scatter everywhere.  

BTW,  my dad was a photographer and he used to bring mercury home for his photo lab use.  My sister and I sometimes played with it, rolling the little balls back and forth.

For the record, my dad passed away at the age of 94 as a result of a broken hip which was not diagnosed until too late.  He took no prescription drugs, was in good health (mental and physical) and was riding his bike each day until the evening he tripped on a throw rug and fell.

My sister is in good health, as am I.

I think your cast iron Dutch oven is safe.

00Eve00's picture

I'm not totally sure, but I think the liquid in most thermometers is alcohol.  Mercury was removed due to concerns of poisoning. 

Here's a picture of mercury if you're interested.  They look pretty much like Lindy described.

davidg618's picture

in a thermometer is probably alcohol and dye. The dye makes it easier to see. Mercury is no longer used in thermometers because of its health dangers, which are real. I suspect, however, the ban was made to protect workers exposure, not the rare occasional exposure from a broken mercury thermometer.

The expression "mad as a hatter" comes from hatters being exposed to mercury vapor. Mercury was used in the curing of pelts used for making hats. A symptom of mercury poisoning is erratic, confused, or eccentric behavior.

Your Dutch oven is safe to use. Just don't drop it on your toes.

David G.


Mini Oven's picture
Mini Oven

that if there is a break of a mercury thermometer, it should never just be "thrown out" but handled as toxic waste.  Mercury should not go into a public dump where it can poison the ground but be brought into a recycle center.  It is a metal and heavier than oil.  In the case of breaking in a pan of oil, it would collect as a shiny blob or "pearls" on the bottom of the pan to easily pour into a small jar to be disposed of properly. (or bring it to your high school or univ. chemistry dept.)

The next is the thermometer.  Candy glass thermometer in oil?  May I suggest a metal one for replacement?  They also test bread better.  I would discourage using a glass thermometer to probe bread, it would break, at least on my crust it would.  And the broken glass can cut me or leave glass splinters in the crumb.  Who want's a bloody crumb? 

The glass variety are pretty tough but they are sometimes stored in a drawer with loose utensils that bang around when the drawers are opened and closed.  That banging around can lead to minute injury of the glass and then when the thermometer is used, sudden rise in temperature can cause it to completely break or shatter. 



vince hav's picture
vince hav

thanks everyone for your expertise....i felt better knowing that i didnt ruin my cast iron or my food that i cooked in it after cleaning it.. i waited till after i read all the post before i tried it...i sure wasnt lookin forward to throwing out those boneless chicken breast strips battered in hungry jack buttermilk pancake mix...they were good after i knew i wasnt gonna die if i ate them...thanks again for all you help...