Chemistry of Cleaning 
Premier Maintenance Co. Inc.

Once you understand the chemistry of cleaning, you can clean almost anything with a few simple items.  The answers you will find on this page are of a general nature.  You will discover the best all-purpose cleaners and why they work.  If you are looking for answers to more specific questions (i.e. how to remove ink from cloth) please see our cleaning FAQ page.

The Four Basic Stains

Greasy Stains:  Most of the every-day stains you encounter around the house will be greasy stains.  For our purpose, greasy stains are stains caused by food, or human and animal oils.  Examples of such stains are:

• Body oils (ring around the collar, oil buildup on armrests)
• Animal Fat (i.e. food grease)
• Carbohydrates and Proteins (i.e. most food stains)
• Some Soap Scum

Inorganic Stains:  For our definition, inorganic stains are:  stains that are soluble (can be dissolved) but are not alive and did not come from a living organism.

• Scale/lime deposits
• Rust, Corrosion and Oxidation
• Minerals and Rock Formations
• Water Spots
• Some Soap Scum

Petroleum-Based Stains:  Petroleum-based stains are not water soluble and must be removed by alternate means.

• Motor oils
• Axle Grease
• Gum
• Paint
• Tar
• Lipstick/Make-up
• Sticker and Sticky-label leftovers.
• Ink (Ink is not really petroleum-based, but it's put in the category because it is most easily removed by cleaners such as paint-thinner, alcohol, and turpentine or mineral spirits.)

Combinations Stains and Special Stains:   These stains are often the hardest to remove, and can be just about anything.   They are more complicated than the above listed stains because they often contain dying agents that alter the chemical composition of whatever they were spilled on.  Although sometimes these can removed with a simple cleaner, sometimes they require multiple cleaning methods that react with different qualities of the stain.  Examples are:

• Mold, Yeast
• Blood
• Grass 
• Mustard
• Coffee
• Alcohol (Wine/Beer)
• Bacteria and Animal Waste
• Vomit

The Simple Stain-Removal Rules

1. Greasy stains require alkaline (or base) cleaners.
2. Inorganic stains require acidic cleaners.
3. Petroleum-based-stains require cleaners that do not require the stain to dissolve in water (i.e. require cleaners with solvents other than water).
4. Combination and special stains may require a combination of the above methods.  If you can't identify the stain, assume it has both a greasy and a non-greasy component.  For all complicated stains a general rule is:  treat the greasy component first with an alkaline cleaner, such as a detergent or soap.  Rinse and dry fully.  Then use an acidic rinse such as vinegar.  Rinse and dry again.

Of course there are exceptions, but these rules work well in general.

Acid/Base Definition 

Basically:  A base is something that releases OH (hydroxide)  when it reacts with water.  An is acid something releases H (hydrogen) in when it reacts with water.  

A few more details:  Water is made up of two hydrogen atoms and one oxygen atom (H₂0).  When other chemicals react with water, these chemicals cause some of the molecules in water to break up into it's two component parts:  OH^- and H⁺.  Depending on the chemical used, the chemical will then bind (react with and "tie up") some of the free OH^-  or H⁺ so the solution then has a higher concentration of left-over H⁺ or OH^- particles.  Chemicals that create more H⁺ particles are acidic.  Those that create more OH^- particles are basic.  Water, as you may have guessed, has equal amount of free OH- and H+  ions and is, therefore, neutral.  

Examples of Acid/Base Cleaners

You'd be surprised to find out how many of the shelved cleaning solutions are really only combinations of some basic home ingredients:

Basic/alkaline cleaners:  baking soda, borax, soap and detergent, bleach, ammonia, lye/caustic soda (basically Draino, use with extreme caution). 
Acidic cleaners:  lemon juice, vinegar, club soda, ketchup, fats and oils (sunflower oil, lard, olive oil...etc) 
Cleaners for petroleum-based stains:  kerosene (lighter fluid), turpentine, rubbing alcohol, fingernail polish remover, WD-40, Ben Gay, paint removers, De-solve and (sometimes) peanut butter.

The More Complicated Stain-Removal Rules

That being said, there are, of course, more things that go into cleaning than the pH (the acidity or alkalinity) of a solution.   

Sometimes cleaners made from simple household ingredients will outperform the marketed cleaners.  On the other hand, there is a lot of chemistry that has gone into the commercial cleaners.  A good commercial cleaner wets, loosens, breaks up, suspends, dissolves, disperses and prevents the re-deposit of dirt or stains.  The following are some of the ingredients that go into commercial cleaners:

• The solvent:  The solvent (oftentimes water) is the medium that loosens the stain by allowing for suspension of the dirt/soil particles.   Water is the most common and oldest solvent known to man.  Some commercial cleaners use other solvents (such as methylene chloride) that will dissolve stains that are water-resistant.
• Surfactants:  Basically soap or a man-made substitute.  Surfactants is short of "surface active agent" because it interacts with the surface/interface between the dirt and the solvent.  Soap is one of the oldest cleaning chemicals known to man because it has a unique property.  Each molecule of soap has a water-loving (hydrophilic) and water-hating(hydrophobic) end.  

(Source:  KCPC Education Resource)

• Other Surfactants:  Besides soap and detergent, commercial cleaners often use other types of surfactants.  Sometimes, they combine several different surfactants all created to do slightly different tasks.  Specifically-engineered surfactants can be added for:  

• Saponifiers:  Saponification is one of the oldest chemical reactions known to man.  Saponifiers are strongly basic chemicals (like lye) that convert animal fats (also called fatty acids) to soap.  Once the fat/grease has been turned to soap, it washes away easily.   

  Animal Fat (Triglyceride/Fatty Acid) + Strong Base (NaOH/KOH) = Glycerol + Soap (CH₃(CH₂)₁₆CO₂^-Na⁺)

• Chelators:  Some areas have particularly 'hard' water.  This simply means that the water has a lot of dissolved minerals in it.  Unfortunately, this often makes regular soap and water less effective because the soap gets 'confused' by the minerals.  Soap molecules can't tell the difference between the dissolved minerals and the dirt they are supposed to clean.  Hence, chelators are often added to bond with or 'tie up' the minerals in the water so the soap is free to do its job on the dirt.