After each use, apply dish soap, warm water, and the rough side of sponge to remove any buildup from your cook. Don't use steel wool or other abrasive scrubbers, as this may scratch your cookware. Rinse your pot or pan and dry it with a dish towel.
Oh no, after using my HP Cooker for the first time, or in a new location for the first time, all of a sudden the pot and basket turned ugly brown or black. What happened? Did the metal suddenly fail?
No, your cooker is perfectly fine, besides the look of it that is! What has happened is that you have boiled water that contained an unusual high amount of minerals. This is called a patina effect to the metal. The reaction between high heat and minerals in the water can cause aluminum to darken or discolor. This is a perfectly normal reaction to science between materials. This color will also diminish the intensity over the next several boils, so before wanting to clean or restore it right away, give it a few boils to see how it settles back to a milder grey like finish.
Is it safe to still cook in the pot, given the discoloration? Yes, it is perfectly safe for continued use.
Can my pot be returned to normal looking color or condition? Yes, there are several methods to try to return your pot to original form. However, should you use it again in the same water environment, it is likely to discolor again, but probably not to the extreme dark color as the original instance.
To remove black residue, fill the cooker with X number of cups water and add X number of tbsp. of white vinegar.
Example 5 gallons of water, (16 cups per gallon) is 80 cups of water. Therefore you will need 80 tbsp of vinegar. (1 cup = 16 tbsp) 80 tbsp/16 tbsp = 5 cups.
Boil the white vinegar solution in the cooker for several minutes until the water becomes very dark.
Drain the solution down your drain and repeat the process until the black residue is gone.
Scrub the outside of the pot with a scrubbing pad soaked in white vinegar to remove any black stains that may have developed on the outside of the pot from the water.
Additional articles of help regarding the cause of discoloration and cleaning steps: