Friday, October 12, 2012

Why I dont use glass bakeware

Ever wonder why some people do not use glass bake ware for baking? This is why. The picture to the left shows a Pyrex brand glass baking dish that exploded in the oven. The science behind this is somewhat interesting, well to me it is because i am an engineer. Haha. The phenomenon is known as Spontaneous glass breakage. And yes, this has happened to me.

This occurs when toughend glass, also known as tempered glass, suddenly, with out apparent reason, to the naked eye, explodes. But, there are scientific reason of why this happens. One of the most common casues, believe it or not, small nicks and chips inthe material. This causes weakness and stress points in the glass. Think of it as the weakest link in the chain theory. As the temperature rises and falls, the glass will expand and contract. This is normal behavior, but when you have a chip in the glass, it causes the chip and exposed material to continue to crack and lose integrity.  A solid piece of glass can withstand the contraction and expansion because the whole piece of glass is behaving the exact same way. When a chip ocures, the structure of the glass is changed immensely, therefore, when it contracts or expands, it continues to break down at those weak points. Think of it like a brick wall. As you push the wall and even punch it, no damage. The mortar holds strong. But what happens when some of the mortar is cracked and even missing? The individual bricks begin to move about and cause deterioration. not a good thing.

In the past years, manufactures have switched from a  Borosilicate, an organic compound made of silica and boron oxide, to soda lime. Boron oxcide is a mixture of a natural mineral called boron found in the bottom of dry lake beds. Boron is used in laundry soap and many many other uses.Borosilicate has a very low thermal expansion rate. This means you will not get heavy amounts of contraction and expansion in the glass from temperature changes. This is a very good thing. However, soda lime does not have this ability. They switched because it is cheaper to produce. Soda lime glass also has other natural occurring minerals in them.

So, in short, if you use glass bake-ware, cook at low temps and by all means make sure there are no chips. Not even small ones. It might just be worth it to spend the same amount of money in stainless steel bake-ware or invest in some nice stoneware. I use a baking stone and stainless. I still occasionally use my glass bake-ware and aluminum, but not very often. I hope you enjoyed this article. I know it probably is boring but i LOVE science.

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