Pipes for plumbing, especially copper pipe, is prone to an accumulation of mineral deposits. If you live in an area that has water heavily treated with chemicals you will notice more mineral deposits. Hard water carries heavy amounts of calcium and magnesium. When these minerals are left to crystallize they form a whitish, powdery substance. There are other minerals that can also leave deposits on copper pipe. Manganese will leave a brownish black stain behind; high iron content will leave a white or ruddy slime, whereas copper and brass will both deposit a residue that is bluish green. The article that follows will show you how to remove mineral deposits from copper pipe.
Step 1 - Act Early
The first thing to note is to not leave mineral deposits sit on copper pipe too long. If you see that they are forming you should clean it as soon as possible. When mineral deposits are left on copper pipe too long they can actually etch the metal. When this happens you cannot clean off the deposits and you have to replace the copper pipe. Keep in mind though that you should not get rid of the copper pipe or fixture before attempting to clean the mineral deposits.
Step 2 - Paper Towel Wrap
Vinegar is a very strong solvent. It can remove stains as well as breakdown chemical deposits. Take several sheet of paper towel and stack them together. Soak the towels in white vinegar and remove the excess vinegar. You do not want to have the paper towel soaking wet so it slides off the copper pipe. When you are satisfied that the paper towel is saturated through with vinegar you can then wrap the affected area of the copper pipe with it. Allow the vinegar to do its job for at least an hour to let the vinegar work its way through the minerals. Remove the paper towels and rinse off the vinegar.
Step 3 - Paste Application
Cream of tartar, when mixed with white vinegar, will create a chemical reaction that can eat through tough mineral deposits. Place cream of tartar in a plastic bowl. Slowly drizzle white vinegar into the bowl. Just a few drops may do the trick. Mix the vinegar and the cream of tartar together. You are looking for it to turn into a stiff paste. If the mixture is too thin then add more cream of tartar. If the mixture is too thick to spread then thin out slightly with more white vinegar. Dip a dry paper towel into the paste and start scrubbing the area of the copper pipe where the mineral deposits are. Do not be afraid to apply a lot of pressure. The friction you generate will help remove the mineral deposits. Rinse the paste off the pipe. Repeat steps two and three, but instead of using a paper towel to scrub the copper pipe you will use the stiff bristled brush.