"Before a Black Clay, La Chamba Piece is used for cooking the first time; it should be “cured” to seal the pores. Most pieces, since made with the best quality clay, will likely not need curing and can be used after light wash and slowly boiling some water, however, It is still a good idea to seal and cure the piece.
Every culture has different methods of sealing and curing their clay cookware. The most traditional method used in Colombia is to warm the clay piece slightly, then thoroughly rub the inside with a ripe plantain (a regular banana will do), leaving a thick coating on the clay. After drying for a bit, the piece can then be lightly washed to remove the residue.
The sealing can also be done with almost any oil, or even as easily as filling the piece with a mixture of milk and water and boiling it for a few minutes. During the boiling, some seepage may occur which is quite normal, however, the boiling action will eventually seal the pores.
Finally, to cure the piece, start sautéing some onions or garlic with a little oil or butter. This will finish the process and you are then ready to begin cooking." ancientcookware.com
Before you use your clay Chamba cookware for the first time, the piece should be filled three-quarters full with water and placed uncovered in an oven for 30 minutes at 400ºF. This usually seals the cookware, although a complete seal is sometimes achieved only after it has been used several times for cooking. Boiling milk in the vessel may help if it is still found to be too porous, but this is rarely necessary. All of the cookware and tableware can be used over any direct source of heat, including an open fire. Over time you will notice changes in color of the pot from exposure to the heat source.
After it has been seasoned, Chamba cookware cleans easily. A quick soak and wipe down with a sponge or soft cloth is all you need to clean it. Cleaning in the dishwasher or use of abrasive cleaners is not recommended, nor should you soak your Chamba for long periods of time.
There are no toxins used in the production of La Chamba dishes. The pieces are not glazed and there is no lead found in the clay. The black color comes from the firing process and the smooth finish of the pieces is the result of painstaking hand-burnishing with stones." mytoque.com