Kashrut – Kashering

Question:  I will be re-kashering a Hillel kitchen soon and need some assistance. How long must one boil water in pots used on top of the stove to kasher them?  Must each spoon/knife/fork be dipped individually to kasher?  For how long must they be immersed?  How does one kasher pans used in the oven, and for how long?  After the ovens (gas) have been cleaned, and I have waited 24 hours, how long must they be heated at their highest temperature?

Answer: Kashering pots and pans, silverware and other utensils:

After cleaning them thoroughly, and letting them sit unused for 24 hours, immerse them in actively boiling water.  The water should come in contact with every surface of the utensils.  They only need to stay in the water for an instant.  You then immediately rinse the utensils in cold water.  I usually place utensils in a net bag, and lower the bag into the water.  I kasher more than one at a time, but I make sure that there are not so many so that the boiling water cannot come into contact with every surface on the utensils.

If you have a pot that is too big to fit into another pot, you may kasher it by cleaning it thoroughly and letting it sit unused for 24 hours; fill it to the top with water; bring it to a boil; drop a stone or piece of metal into the water so that the boiling water overflows the pot and runs down the sides.  The pot is now kosher and parve.

To kasher an oven, clean it thoroughly, do not use it for 24 hours, and turn it on the highest temperature setting until every surface inside the oven is heated to that temperature – approximately one hour.  If it is a self cleaning oven, simply run the cleaning cycle, and wipe it out with clean dishcloths or paper towels afterwards.

Pans used directly inside the oven are very difficult to kasher.  They must be scoured thoroughly and left unused for 24 hours; and then every surface must be heated until it is sufficiently hot that a piece of paper held to it will be singed.  This is usually done with a blow torch, although it could be done by putting it into an extremely hot oven for about an hour.  CAUTION – this process will often destroy the pans – they are not designed to withstand such temperatures for that length of time.  If you are kashering for Pesah, I would suggest buying new pans and reserving them for Passover use each year – or using disposable aluminum.

NOTE – When I say “clean thoroughly” or “scour” I mean that every single food stain and discoloration must be removed, from every surface, edge, and crack.  This is especially difficult around handles, and you probably will need to remove them and kasher them separately.  If it is not possible to clean them to this degree, it is not possible to kasher the utensil.

Question:  I have two Kashrut questions, both picky!

(1)  If I have to kasher the oven and a broiling pan, do I kasher the oven first?  Would the act of placing the treif broiling pan in the kashered oven render the oven treif?

(2)  If I place a (clean) meat knife in, say, a mustard jar, does that render the mustard unfit for dairy use?  And visa versa?

Answer: You may kasher the oven first.  Placing the treif broiling pan in the oven with not treif the oven, and actually the heat necessary to kasher the pan (500+ degrees) will also kasher the oven!

Placing a meat knife in the mustard will not render the mustard itself meat for two reasons:

1)  Since the mustard is cold, the meat quality of the knife will not be transmitted, because food tastes, odors, and particles which render a utensil “meat” or “dairy” are transmitted by means of heat.

2)  There is a principle that spicy foods (like onions) can become meat or dairy, even without physical heat.  However, in this case the tiny amount of meat in the clean meat knife is certainly less then 1/60 the volume of the mustard in the jar, nullifying any potential meat taste which might make the mustard fleishig.

Question: Our barbecue grill is fleishig, and we have decided to go vegetarian at home.  Is there any way to kasher the grill so that we can use it for dairy? Or do we need to buy new grill grates?

Answer: The general rule of kashering is that in order to kasher a cooking utensil, it has to be heated up to a higher temperature than that at which it is used.  First, you need to be able to thoroughly clean the grate so it looks essentially spotless.  Also pay attention to the cover of the grill – make sure that it is not caked on the inside with stuff that could drip down when the cover of the grill is closed.  If this cannot be done, it cannot be kashered and you’d need to buy a new grate.  Next, Make sure that the  grill has not been used within the last 24 hours.  Finally – if it is a gas grill, turn on the gas and let the flame burn on the empty grill for about 35-40 minutes, with at least 20 minutes of that time with the top down.  If it not a gas grill, then you can either take a blowtorch and heat up all the metal so it exceeds the temperature at which you use it to cook, or you could use a lot of charcoal and really build up the coals and let it heat up for 30-45 minutes, until it reaches the hottest temperature that it might reach when used.

Question:  How do I kasher a granite kitchen countertop?

Answer: A granite countertop may be kashered by cleaning it thoroughly and pouring boiling water over the entire surface.

Question:  I received a set of china from my grandmother that she used for meat, and we would like to use it for dairy.  The set has not been used at all for over 10 years.  Must we take it to the mikvah, or has enough time gone by that we can use it anyhow?

Answer: Normally, earthenware, china included, may not be kashered.  The reason is that the material is so porous that food odor and taste can never be removed completely, and thus would co-mingle with any food served on it.

However, an exception is made for heirloom quality fine china.  If it sits unused for one year, it may be treated as new, unused china.  You may then use it without kashering.

Incidently, immersing dishes in a mikvah is not done for reasons of kashrut as we commonly think of it.  In other words, if a utensil becomes treif, immersing it in a mikvah will not kasher it – it needs to be immersed in boiling water.

Mikvah immersion for dishes, for those who follow the practice, is only done for glass and metal dishes which pass from the ownership of a non-Jew to a Jew.  It is done because of a fear that the previous non-Jewish owners or manufacters dedicated the utensils to foreign gods or used them to eat food dedicated to idolatrous gods, and the new Jewish owners need to rid the utensils of the impurity of idolatry, and resanctify them for the one true God.  It is very infrequently done today in the Conservative community because of a common, and true, assumption that the non-Jews who craft our utensils do not dedicate them to idolatrous gods.

Question:  A Circulon frying pan with a plastic handle came in contact with treyf. I cannot immerse the handle in boiling water, can I immerse the metal part of the pan while holding it by the handle?

Answer: I don’t understand why you can’t immerse the handle.  Is it that the handle potentially will be destroyed by boiling water, or is it that you don’t have a pot big enough to immerse the pan and the handle at the same time?

The general rule is that the entire pan should be immersed, but it can be immersed one-half at a time, if it is too big to fit in the pot all at once.  However, if you know that the treif only came in contact with the pan, and there was no chance that it splattered onto the handle, it may be kashered by immersing the pan only.

There is another issue, however.  The rule of kashering is that it should be heated up to the same temperature at which it was made treif.  That is why baking pans used directly in the oven cannot be kashered with boiling water, but need to be kashered either with direct flame or by placing them in a 500 degree oven.  The cooking surface of a pot used for boiling does not get hotter than 212, the boiling point of water, so it can be kashered with boiling water.  But a pan used for frying can get much hotter, and is more similar to a utensil that is used directly in the oven.

Question:  If a Cuisinart bowl is used for meat and it sits for 24 hours can  it be used for pareve? Why or why not?

Answer: In order to kasher the bowl (or anything which might come into contact with food and heat – including, in this case, the hot water used to wash it afterwards), you need to immerse it in boiling water.  It should be clean and unused for 24 hours before kashering, but this alone does not complete the kashering process.

The theory behind the kashrut of utensils is that food particles are absorbed into the utensil.  This food taste can be released in the same way it was absorbed, by means of cleaning with hot water.

Question:  Could you please make it  a little clearer.  Since a cuisinart bowl is plastic does that mean that you can kosher plastic?

Answer: Yes, plastic can be kashered if it can be immersed (briefly) in boiling water.

Question:  Can plastic be used for meat and then pareve?

Answer: Plastic, unlike glass, is not parve.  It takes on the attributes of the food stored in it.  Therefore, under normal circumstances, food stored in meat containers should not be served with a dairy meal.