Can you kasher glass

Some can be kashered [made kosher], some cannot, some are debatable. Whether or not you can keep the dishes you already own depends on the material from which they are made.

Unglazed earthenware cannot be kashered at all, as the porous ceramic permanently absorbs juices and flavors from foods.

Nowadays, glazed chinaware can be relatively inexpensive, especially compared to 50 or years ago. The general opinion is, chinaware cannot be kashered. This is the amount of time deemed necessary for dissipation of all unkosher flavors.

If the glaze is thin and could easily flake off, the dish likely cannot be kashered. The alternative is to find a kiln and heat the ceramic items at kiln temperatures about 2, degrees Fahrenheit , but at that heat the china might break. Teapots, if they were never used with flavored tea, may not need to be kashered and can be kept; check with your rabbi. Glass has been controversial, in both Conservative and Orthodox rulings, in terms of determining what material category it fails under.

Yet it does not absorb as earthenware does, so is it like metal? However, because glass is neutral, the question has been raised: Could the same dishes be used for dairy and for meat, just washing them in between uses?

While technically this is a possibility, both Conservative and Orthodox rules frown upon this as a practice. Keeping track of when you used the dish last, if you washed it appropriately, and so on make it problematic to use the same glass dishes for hot dairy and meat foods. However, a "mistake" can be rectified by kashering.

It is Absorbed flavors Can not be used for absorbent cannot be removed both meat and milk. Also, cannot even be kashered if a "mistake" was made. Glass is made from sand, and would therefore seem to be in the same Halachic category as earthenware which is super-absorbent and cannot be kashered. On the other hand, the resultant glass vessel is hard and smooth - unlike earthenware - which would indicate that it is non-absorbent, and would therefore never need to be kashered.

Glass is a difficult material to classify Halachically, because it shares its origin with one class of material, but has physical characteristics that differ from items of that class.

Because of these unusual characteristics, there are a few different opinions in Jewish Law concerning glass dishes: Rav Yosef Karo rules that you can use glass for both milk and meat, and just rinse them off in between. Rav Moshe Isserlish writes that glass is like earthenware, and it is therefore forbidden to use the same dishes for both meat and milk. There is a third opinion that holds that glass is absorbent, but that it can be kashered through the process of " hagala" immersion in boiling water.

Mishna Berurah addendum to writes that although the Chasam Sofer was against kashering metal pots that are coated with glass with hagalah, he has heard that many Gedolim are maikel to kasher these pots when they are aino ben yomo, and are only machmir not to kasher them for Pesach. Similarly, many are maikel to kasher enamel coated ovens, such as the type that are common in homes, with libun kal. However, for Pesach one should lichatchila be machmir to do libun gamur self clean or torching , use an oven insert, or make sure to only place covered food in the oven.

In cases of difficulty, some are maikel to allow libun kal, since the Magen Avrohom said that if one kashered glass it would help bedieved. Glass lined reactors glass lined steel accordingly may be kashered with hagalah. Although we do not kasher glass, we allow caterers to use hotel glasses. This is because the glasses are clean and are only used with cold drink.

Rama Y. Caterers may not wash their own glasses in a treif hotel dishwasher, since this will make their glasses treif, and continued use is considered derech kevah.

Some pipes have a sight glass for viewing product. If hot non-kosher product flows through this pipe, can it be kashered? Heter includes chalav stam provided that the kli being kashered is aino ben yomo.

If the bliya was from other issurim, it is subject to the machlokes the Mechaber and Rama, and our minhag is not to kasher lichatchila.