I have inherited a glass baking dish from a former roommate. The inside feels clean to the touch, but the outside is stained and feels gritty. The only thing that seems to get it clean is baking soda and a whole lot of elbow grease. I have read, though, that using abrasive cleaners on glass dishes means they could develop microscopic scratches, which make the glass more likely to shatter in the heat of the oven. Is this true? If so, what else can I use to clean the dish?
All I can tell you is that I clean my glass and Pyrex dishes with baking soda and have never had a problem. This sounds like an urban legend to me.
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From Wikipedia, I find that the mineral form of baking soda is nahcolite, which is 2.5 on the Moh’s scale, while glass is at 5.5 or higher. So it seems unlikely to me that you could scratch the baking dish.
Putting it all together.
There *are *abrasive cleaners on the market harder than glass. e.g. powdered kitchen cleansers like Comet. Those will scratch glass. Which may not lead to shattering but will definitely lead to increasingly grungy glass that gets dirtier more easily and become progressively more difficult to clean.
Baking soda is not one of those hard abrasive cleaners. It’s a soft abrasive cleaner softer than glass. Which also means it takes a lot more elbow grease to grind off the gunk, since it’s the ratio between gunk hardness and abrasive hardness that paces the results. In fact there’s probably some stubborn baked-on varnish that’s harder than baking soda that baking soda can’t remove even with infinite elbow grease.
That’s your tradeoff. Happy scrubbing.
You could try Barkeeper’s Friend. It doesn’t scratch, but uses a different chemical to help clean.
Wikipedia says that Comet uses calcium carbonate as an abrasive, which has a Mohs hardness of 3.
Is hardness as straight forward as people are making out? Rubbing something of lower hardness on something of higher hardness will leave no marks on the harder thing. That seems way to simple for something as complex as friction.
From the Wikipedia article on the Mohs scale, “Frequently, materials that are lower on the Mohs scale can create microscopic, non-elastic dislocations on materials that have a higher Mohs number. While these microscopic dislocations are permanent and sometimes detrimental to the harder material’s structural integrity, they are not considered ‘scratches’ for the determination of a Mohs scale number.”
This answer also helps with the “does lock licking leave scratches?” question.
Might not help you if its gritty, but I use bleach on a pyrex measuring cup that I heat tea in. The tea eventually stains it, and a little bleach will take it right off.
I think the chemical in Barkeeper’s Friend is oxalic acid, which is a rust remover. It’s meant for cleaning metal surfaces. I don’t know how effective (aside from its abrasive qualities) it would be on glass.
Why would the inside be smooth and the outside feeling rough ?
Because the inside has already been polished by scouring … Just scour the outside too.
scouring means using any of the scouring pads and/or grit detergent mixes.
Short of using rock cutting equipment, you are fine to scour and scratch the pyrex.
Crystals are what suffer weakness due to “dislocations” but pyrex is resistant to that, its not an issue until there are literal scratch marks.
“Heat tea” and putting bleach in a pyrex cup both put my teeth on edge. Tea leaves need boiling water to release all of the flavour, there are many better options for making tea in, and bleach is considered to be hazardous to your health by many.
The BKF FAQ says it’ll work on glass. Due to the micro-abrasives, though. Basically the product’s name indicates that glass is one of its primary targets.
eh, I’m not that much of a connoisseur. I heat water with a teabag in a pyrex measuring cup in a microwave and put it in a travel cup for my drive to work. I will bleach the measuring cup perhaps twice a year.
I have used Wright’s copper cleaner to remove residue from metal bakeware and utensil marks from Fiestaware and other china. It may work on Pyrex too.
Bleach is not cyanide. We put chlorine in drinking water! Even pure bleach will rinse out of glass, and any residue left would evaporate long before the mext morning.
Doesn’t bleach disassociate into salt water? Sodium Chloride?
It isn’t a cleaner either, it’s a disinfectant and stain remover. Anyway, I know it’s used safely millions of times a day, I used it to make sure surfaces are germ-free after I’ve cleaned them.
Well, it sure feels like it when my cat licks me.
Anyway, to the Pyrex bit- steel wool pads (Brillo, S.O.S.) work fine on glass, and won’t scratch at all if you don’t put all your weight into it.