fresh

tempered glass dinnerware ?

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I am given a tempered glass dinnerware which can be used in microwave. The problem is it is tea-color. I have no idea why it is tea-color ? what is the chemical added to become this color ?

 

tempered glass utensil.jpg

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Probably a mixture but I'd expect that it's largely manganese that is giving that colour.

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6 minutes ago, Strange said:

This page has a table of additives used in coloured glass: https://geology.com/articles/color-in-glass.shtml

Looks like it could be iron or manganese oxides.

thank you. it looks like ..

Carbon Oxides Amber-Brown

why add it to utensil ? is it good for health ?

What Causes Color in Stained and Colored Glass_.html

3 minutes ago, John Cuthber said:

Probably a mixture but I'd expect that it's largely manganese that is giving that colour.

why need add manganese ? 

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23 minutes ago, fresh said:

why add it to utensil

Just to make it look nice.

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Posted (edited)

and this one is also added manganese ? manganese dioxide is a decoloring agent. why i think it looks like amber-brown added by carbon dioxides ?

 

utensil2.jpg

utensil1.jpg

Edited by fresh
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Any compound that is likely to leach into your cooking water would be on the surface and will have been removed in the first washing up or two. The rest is safely sealed in the glass.

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It makes no sense to talk about adding oxides of carbon  (which are gases or too unstable to exist in molten glass).

That web page is wrong.

You could add carbon- which is black.

 

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On 8/3/2019 at 10:14 AM, fresh said:

I am given a tempered glass dinnerware which can be used in microwave. The problem is it is tea-color. I have no idea why it is tea-color ? what is the chemical added to become this color ?

 

tempered glass utensil.jpg

Just wanted to clear up a few things.

This cookware is called Visions and it was invented Corning inc.

It is not tempered glass!  Tempered glass would be a terrible idea.  A small scratch could result in a catastrophic failure of the cookware when heated.

Visions is a glass-ceramic.  To make it glass is molded to the desired shape and then the glass is heat treated so that it devitrifies (crystalizes).  The crystal structure has a very low CTE so that when it is heated or cooled there only very low stresses on the body, well below the stress needed for failure.

My understanding is that the color is primarily due to the crystal structure, this part could be wrong.  My info is from what I recall my wife telling me.  She is a glass technologist who worked for Corning for 35 years.

Here is the wiki on visions

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That's interesting.

Devitrification normally stops the glass being transparent.

It must have taken some clever  work to get the crystals to have the same refractive index as the glass matrix.

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19 hours ago, John Cuthber said:

Devitrification normally stops the glass being transparent.

It must have taken some clever  work to get the crystals to have the same refractive index as the glass matrix.

you are right.  what's the clever work to make it transparent ?

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