Removing Mineral Deposits from Household Surfaces

By Dr. Sandra A. Zaslow, Extension District Director,
North Carolina Cooperative Extension Service

(Note from NH:  Though the methods below are useful, there are situations where chemical changes to the materials have occurred and NOTHING will restore the material to its original condition.  For example, streaky or milky-colored stains on shower doors are often permanent because the glass has actually been etched by the reaction of water-borne chemicals. 

These can be prevented through the installation of water softening equipment or (for the thrifty) simply wiping the doors dry after use.  Also, plated plumbing fixtures that have become discolored can be cleaned, but often (especially on cheap brass plating or chrome) the coating has been destroyed and no amount of cleaning can restore it.)

If you have hard water, you probably have more than your share of scum, film, and lime deposits on a number of household surfaces. These unattractive deposits can appear on china, porcelain, enamel, tile, stainless steel, fiberglass, chrome, and glass surfaces.

Hard water increases films and stains from soaps, minerals, and other substances. Bathroom fixtures, sinks, dishes, and other surfaces need more frequent cleaning.

Calcium and magnesium in water leave hard deposits -- called lime scales -- on fixtures and equipment. These minerals make cleaning products less effective. To clean away lime scale, you need a cleaning product with "sequestrants." Sequestrants capture and deactivate minerals in water. (Calgon is one example of a product with sequestrants.) The deactivated minerals then cannot react with other materials to form scum, film, or lime scale.

You may also have problems from manganese, iron, brass, or copper. Manganese leaves brownish or blackish stains. Bacteria that thrive in water with a high iron content leave a reddish or white slime. Brass and copper content in water are the result of acidic water. When water is a bit acidic, it corrodes plumbing and fixtures. If you have brass or copper fittings, you may end up with blue or green stains on fixtures. To remove any of these metallic stains, use an acidic cleaner or an all-purpose cleaner.

The general types of cleaners discussed below will help you to remove stains on household surfaces. It's best to clean stains away regularly. If they are allowed to penetrate the surface, they become more difficult to remove. Be sure to follow label instructions for safe use of cleaners. You may need to open a window or use a fan to get proper ventilation.

Remember, some cleaners, such as ammonia and bleach, should never be mixed or used together because they can form toxic fumes. Store cleaners in a safe place and properly dispose of empty containers.

Acid Cleaners

Acids help remove hard water deposits. Some acid cleaners help remove discoloration from aluminum, brass, bronze, and copper. Other acids remove iron rust stains. Acids are typically found in toilet bowl cleaners, rust removers, metal cleaners, and kitchen and bath cleaners that remove mineral products.

• White vinegar, a weak acid, is about 5 percent acetic acid. It may remove hard water deposits from glass, rust stains from sinks, and tarnish from brass and copper.
• Lemon juice, another weak acid, contains citric acid, which can be used in much the same way as vinegar.
• Oxalic acid is effective as a rust remover.
• Phosphoric acid is often found in cleaning products that remove hard water deposits.
• Hydrochloric and sulfuric acids are sometimes used in diluted concentrations in toilet bowl cleaners.

Rust stains present a special problem on plumbing fixtures. Commercial rust removers contain oxalic acid. If you purchase oxalic acid at full strength, dilute it with 10 parts water. Follow all precautions when using oxalic acid, as this is a highly toxic product. A commercial product like ZUD may be effective on rust stains because it contains oxalic acid. When surfaces have become rough or pitted from repeated scrubbings with an abrasive cleaner, ZUD or a similar product may be mixed with water to form a paste and left standing on the stain for several minutes, then rinsed off.

For fixtures that are not acid resistant, clean with trisodium phosphate to remove the rust. Cream of tartar, a mild acid, may be mixed with water to form a paste rust remover.

Abrasive Cleaners

Abrasive cleaners like scouring powder may remove or lighten stains. Regular use of harsh abrasives scratches the finish of sinks, bathtubs, or other fixtures. Once the surface is dull and rough, it will get dirty faster and stain more deeply. Even mild or fine abrasive cleaners may eventually scratch or dull surfaces. Do not use abrasive cleaners on fiberglass, ceramic tile or glass.

Chlorine Bleach

Chlorine bleach can help remove some stains. Don't leave it standing for long periods of time, as it will dull shiny porcelain enamel surfaces.

Specialty Cleaners

Some specialty cleaners are formulated to remove hard water deposits, soap scum, or rust stains. Lime-A-Way is one example. Tub, tile, and sink cleaners that remove soup scum and water hardness may contain sequestering agents and acids such as phosphoric, hydrochloric, or hydroxyacetic acids.

All-Purpose Cleaners

Nonabrasive, all-purpose cleaners (like "409") in powdered, liquid, or spray form are safe for most plumbing fixtures and can be used for regular cleaning and for removal of hard water deposits and soap scum if the deposits are not heavy accumulations.

Stains at a Glance

Red, reddish brown (from rust or iron)

• Paste of borax and lemon juice; let dry, then rinse
• or
• Paste of mild scouring powder, cream of tartar, peroxide; let stand 1/2 hour, then rinse
• or
• Trisodium phosphate in water, then rinse
• or
• Commercial products (like ZUD), then rinse
• or
• Oxalic acid, 1 part to 10 parts water, then rinse

Green, blue-green stains (from copper or acid water)

• Soap suds and ammonia, then rinse
• or
• Mixture of half water and half ammonia; rinse well and flush pipes with water after using

Brown, black or others (from manganese and other minerals)

• Paste made of cream of tartar and hydrogen peroxide; let stand, then rinse

Hard-water marks, soap scum

• Paste made of white vinegar and baking soda; let stand, then rinse
• or
• 1 teaspoon Calgon in gallon water, rinse well
• or
• 2-4 tablespoons trisodium phosphate in gallon water, then rinse

The use of brand names in this document does not imply endorsement of the products named or criticism of similar ones not mentioned.

Prepared by Dr. Sandra A. Zaslow, Extension District Director, North Carolina Cooperative Extension Service, North Carolina State University, Raleigh, N.C.

This publication has been issued in print by the North Carolina Cooperative Extension Service as publication FCS-397 and WQWM-12 (February 1993). Published by
North Carolina Cooperative Extension Service
North Carolina State University, Raleigh, N.C.