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Corningware and other cookware unsafe if scratched, chipped?

post #1 of 16
Thread Starter 

I don't want my food touching anything unsafe. What is under the top layer of Corningware? When scratched, the scratches look grey. I was planning to replace the scratched and chipped ones. Also the chipped glass lids or glass pans. I think I read to stop using enamel cookware and dishes once they are chipped. Only the top layer is safe and the inner part isn't?

post #2 of 16

Quoting from Corningware's site http://corningware.com/index.asp?pageId=80

 

Quote:

 

Do not use or repair any item that is chipped, cracked or severely scratched. (1)

I suspect the (1) refers to a note my browser won't pull up.

 

For scratches from general use, you should be fine.

 

My understanding is this (1) has to do with the bakeware shattering than being toxic. Basically these are all flaws that thermal shock can propagate along. This is an issue for glass an ceramic cookware.

post #3 of 16

The old corningware was virtually indestructable.  However, Pyrex sold the corning division to an entity that contracted with china to produce it.  They changed the formula and it is no longer as strong and safe as it used to be.   I've spoken with several people who baked ordinary dishes in their clear "pyrex" baking dishes and the dishes exploded without having been mistreated in anyway, just with normal usage.   I have Pyrex dishes from my mother that are over 60 years old and look and perform just like they did when they were new.

DD

post #4 of 16

Most of those explosions can be traced to something wet coming in contact with bakeware. A damp surface will trigger it, say if you just wiped down something before putting the hot bakeware on it.  The older stuff does seem to have been tougher, but there's plenty of those that did the thermal shock shatter as well.

post #5 of 16
Thread Starter 

Oh, yes I'm aware of the lower clear glass pyrex quality. I am not familiar with any other corningware products.

 

I have corningware from the 70's. They are white and nice, but I was surprised that it's silver when scratched. Why is it silver? What is just underneath the surface? I'm glad the insides aren't chipped but it made me nervous, because I want to avoid metals except for cast iron. (Stainless steel sometimes.) I guess the scratches were from utensils.

post #6 of 16

Hi Phatch.

My friend had 2 explode on her on Thanksgiving.   On the first one all she did was take her sweet potaqto casserole out of the oven and place it on her cook-top (metal grate, gas stove) and it not only shattered, it exploded.   Having had thaqt experience, she thought "I'm being sure to place it on something hot this time.  When she took out another dish, she placed it on the open oven door and it did the same thing.  these new Pyrex dishes are dangerous.

 

As for the older ones, I know they withstand thermal shock- at least to a certain extent - because I could not stop my brother from plunging the hot pan into cold-ish dish water.   I used to keep his dinner warm in the oven and he'd spoon all of it out on a plate, then thought he was helping when he put the hot pan in the dishwater to soak.   Couldn't stop him.

DD
 

Quote:
Originally Posted by phatch View Post

Most of those explosions can be traced to something wet coming in contact with bakeware. A damp surface will trigger it, say if you just wiped down something before putting the hot bakeware on it.  The older stuff does seem to have been tougher, but there's plenty of those that did the thermal shock shatter as well.



 

post #7 of 16

Yes, a cooking grate is bad. I've done the same thing with the same result. scared me pretty good when it blew. Think about it. You have lines of high heat conducting metal that create quicker cooling areas in the ceramic. This sets up  the conditions for a thermal shock. Oven door is about the same thing in reverse. The oven door would be close to the temp the oven was set at. The corningware would be quite a bit less, at just the temp of the food. The metal would try to dump heat into the ceramic again setting up thermal shock.

 

You've got to put these baking dishes on an insulator. Folded dry dish towels, hot pads and so on.

post #8 of 16

No, dish was coming OUT of hot oven.  Same temp as the door.

DD

post #9 of 16

There's a dark roux technique where you microwave the flour and fat in Pyrex in 30 second bursts for stirring inbetween. Amazingly fast, dark roux in 2-4 minutes. Amazingly dangerous. Dark roux is around 400 degrees while the handle on the pyrex remained cool. Intense thermal stress in the Pyrex. Many reports of explosions. I did it once and just wish there were a safe way to keep doing it because it's an awesome technique for dark roux.

post #10 of 16
Quote:
Originally Posted by phatch View Post

There's a dark roux technique where you microwave the flour and fat in Pyrex in 30 second bursts for stirring inbetween. Amazingly fast, dark roux in 2-4 minutes. Amazingly dangerous. Dark roux is around 400 degrees while the handle on the pyrex remained cool. Intense thermal stress in the Pyrex. Many reports of explosions. I did it once and just wish there were a safe way to keep doing it because it's an awesome technique for dark roux.


I've heard bad things about this microwave technique too many times to experiment.

 

Do you know the fast way to dark roux on the stovetop? It's a little dangerous, but controlled.

 

Start with a good heavy skillet, preferably cast iron, that either doesn't have corners or has soft enough ones that you can dig into them with your whisk. Heat the oil over high heat until it just starts to smoke. Start whisking quickly and shake in 1/3 of the flour. When smooth, add another 1/3. When smooth, add the rest. DO NOT EVER STOP WHISKING. Make sure you get all over the material and regularly hit all the corners to dig stuff out of it -- you've got to keep everything moving. You will find that it very quickly becomes light brown. At red it will thicken weirdly, and it's super-important to whisk all over during this period. When it gets a shade lighter than you want it, remove from heat and keep whisking rapidly for about 1-2 minutes, depending on how much you've got and how heavy your pan is. If you're doing about 3/4 cup each of flour and oil, the whole process shouldn't take more than 5-6 minutes.

 

Some notes:

  • If at any point it's darkening too quickly, get it off the heat and whisk fast for a bit
  • Watch for little black flecks -- that means it's burnt
  • You can cool it faster by throwing the minced vegetables into it, preferably off heat, and continuing to whisk; you may need to switch to a wooden spoon for this, though. When you do this, the superheated steam will darken the roux, so always start your cooling process -- with or without vegetables, that is -- about 1 shade shy of where you want it
  • Wear long sleeves and long pants and closed shoes while you do this, unless and until you've done it a lot and are very confident -- the stuff gets close to 500F and sticks like Napalm
  • If you don't let the oil get to smoking point first, for some reason it will take WAY longer to finish the job
  • Remember that you can only do this with high-heat fats -- if you want to make a dark roux with olive oil, for example, you'll need to do it the slow, old-fashioned way

 

Last but not least, I seem to recall that Alton Brown prefers a method where you bake it in a hot oven for a long time, stirring periodically. That seems safe and low-impact, but I don't remember the details.

post #11 of 16

Yes, that's much like what I do on my induction burner. Love the fine heat control that offers.

post #12 of 16
Quote:
Originally Posted by Natural View Post

...but I was surprised that it's silver when scratched. Why is it silver? What is just underneath the surface? ...

I'm not positive, but I venture a guess the silver color is from the utensil or object that scratched it. Similar to what happens when washing a metal pot in a porcelain sink.

 

As far as I know, Corning Ware does not have a metal base and the ceramic is the same throughout
 

 

Chef,
Specialties: MasterCook/RecipeFox; Culinary logistics; Personal Chef; Small restaurant owner; Caterer
Reply
Chef,
Specialties: MasterCook/RecipeFox; Culinary logistics; Personal Chef; Small restaurant owner; Caterer
Reply
post #13 of 16

Pieces produced in China or Mexico, by the companies that bought or licensed the Corning or Corelle names, may be composed of various colored clay compounds covered with a white glazing.  These pieces generally have disclaimers about their use such as "Oven use only", "Microwave only", or "No Stove top" or "No Broiler", molded or screened on their bottoms.   

 

If you take a piece original Corning Ware and intentionally break it, unless it has a metalic glazing for microwave heating on the bottom, or decorative colored glazing, it will be white all the way through.

 

The grey or silver appearance of deep scratches or chips in original Corning Ware pieces is due to metal rubbed or deposited on the ceramic during or after breakage.. Often this is from the metallic item that scratched through the glazing.  Rarely, the combination of hot water, caustic detergent and a metallic pan or utensil can cause metal to become dissolved and redeposited in microscopic cracks. When the piece subsequently fractures, the deposited metal is be revealed.

 

Rubbing any glazed piece with a metallic utensil can leave behind metalic traces and discoloration.  This can be seen in the bottoms of  corning coffee cups.  Surface discoloration can be removed with a mild, soft abrasives such as Corning Ware cleaner, glass cook top cleaner, or baking soda.  

 

 

post #14 of 16
Thread Starter 

Thank you. Mine are original and the scratch marks are light. They aren't going away after repeated normal cleaning. I will try the cleaners suggested.

post #15 of 16

IF IN DOUBT, THROW IT OUT.

Chef EdB
Over 50 years in food service business 35 as Ex Chef. Specializing in Volume upscale Catering both on and off premise .(former Exec. Chef in the largest on premise caterer in US  with 17 Million Dollars per year annual volume). 
      Well versed in all facets of Continental Cuisine...

Reply

Chef EdB
Over 50 years in food service business 35 as Ex Chef. Specializing in Volume upscale Catering both on and off premise .(former Exec. Chef in the largest on premise caterer in US  with 17 Million Dollars per year annual volume). 
      Well versed in all facets of Continental Cuisine...

Reply
post #16 of 16

I have a deep square pyrex/Corning pan that I make turkey breast in all the time.   It is circa 1992 or so, I'm hoping it isn't from the new stuff, but it DOES say "made in china".    I'd hate to lose it, it is the perfect size for roasting a turkey breast.  with the lid on, the turkey stays nice and moist, and it is small enough the juice permeates the bottom of the turkey too.   

 

None of mine have any marks on them at all (except some scruffy dark marking on the bottom where it was scooted on the dirty oven rack, and my scrubber du jour didn't get it off..  Yes, in spite of automatic oven cleaner feature, my oven racks are often dirty.   As I mentioned, some of mine are 60+ years old, I inherited them from my mother.  I roast almost everything and could probably cook a long time without missing the burners, except for heating the tea pot.

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