Making Kosher the grill and the oven

Last week we explained what happens with the food when we accidentally we cooked a meat food on a diary utensil or vice versa. Today we will see what we should do with the cookware.
As a general rule, most utensils or cookwares that were used with a prohibited food can become kosher again, but they need to undergo a process of “depuration/sterilization” to get rid of the absorbed particles of the forbidden food. Most people are familiar with the process called “Hagala” which basically means immersing a utensil in boiling water. For example, if one accidentally used a meat spoon to stir dairy food, the spoon needs to be immersed for a few seconds in boiling water.
There are some utensils that are not used with water or for “cooking”: for example, a grill or an oven. The food particles were absorbed there by direct fire or by heat; water therefore won’t be effective in getting the forbidden particles out…
So If one wants to make Kosher a non Kosher grill he needs to do a Libbun Chamur (heavy firing) which means, that the grill must be placed on the fire or heated with a torch until the metal changes its color to red/white.
A regular electric or gas oven needs Libbun Kal (heating) which consists on bringing the oven to its maximum temperature –the highest it might have reached when cooking the non Kosher food- for about half hour. The self cleaning function of most electric ovens is considered Libbun Kal.