Ph

pH of a substance is a measure of its acidity or alkalinity just as degree is a measure of temperature. A specific pH value tells the exact amount of acidity or alkalinity just as 25 degrees tells the exact temperature rather than saying it is hot or cold.
pH is measured on a scale of 0 to 14 with a pH of 7 as the neutral point. pH of a substance is measured essentially of water based substances. The pH level of a cleaning substance can have a profound effect on the cleaning and other attributes of a cleaning substance.

Warning - this is long. If you don't really want to learn about pH don't even start reading.

pH is only one of several factors that effect chemical reactions when cleaning. In orther words pH may be featured on the label, the MSDS etc. but it is not the whole story.

pH tells us how many ions or electrically charged particles are present in a liquid. The number of ions present (pH) is another of the factors that determine if a chemical reaction will take place. You don’t need to know a lot about pH for to use it to aid your cleaning. If you want more detail read the box below. If you prefer to ‘keep it simple’ skip past.


pH – What Do the Numbers Mean?

pH is an abbreviation of a French term. The English equivalent is “power of Hydrogen.” Here is the official definition of pH. pH is the negative logarithm (in base 10) of the number of Hydrogen ions in one liter of a solution.

It is not necessary to fully understand that official definition of pH to see how pH effects your cleaning. However, some of you are asking yourselves. “What does that mean?”

Ions are molecules that have either gained or lost an electron. So they are no longer electrically balanced. They will either have a negative charge (extra electron) or a positive charge (missing an electron).

Water molecules (H2O) are composed of two atoms of Hydrogen (H) and one atom of Oxygen (O). A very few of these molecules will separate into an H+ ion and OH- ion. In pure water there will be an equal number of each. There will be .0000001 H+ ions (10-7) molecules in each liter of water. The pH of pure water is 7, the negative of the power of 10 from counting those ions.

When a substance is dissolved in water the number of Hydrogen ions may increase or decrease. If the result is fewer H+ ions the solution is alkaline. If there are more H+ ions the solution is an acid.


The pH scale ranges from 0 to 14. Numbers below 7 are acid. Numbers greater than 7 are alkaline. The further from 7 the stronger the acid or alkaline. Each whole number difference represents a tenfold change.

Pure water is neutral — pH 7. However, almost anything dissolved in the water, in any amount, will affect the pH. Freshly distilled water rapidly absorbs carbon dioxide from the air and reaches a pH of 5.5 in a very short time. Other materials dissolved in the water may have an even more marked effect. Depending on its chemical characteristics, it can either raise or lower the pH value. Thus the pH of any solution depends on the type and amount of materials dissolved in the water.

Each number on the pH scale actually represents a 10 fold difference. Thus, pH 4 is ten times as acidic as a pH 5 solution. A pH 3 solution, in turn has ten times the strength of the pH 4 solution - and 100 times the acidity of the pH 5 solution. This pH scale of 0 to 14 is derived from the chemical properties of water and this pH scale cannot be used without water.

To help visualize how quickly the strength changes, think of pH 7 being the thickness of a sheet of paper. A pH of 10 is 7”, about as tall as a water glass. Moving to an 11 is the height of an average man, about 5’10”! A pH of 14 would be well over a mile high.

Remember, the pH numbers represent only a part of the picture. Other factors influence if there will be a chemical reaction and how strong that reaction will be. The pH scale does not show the reactivity or concentration of a chemical. The pH chart does not tell us if a chemical will maintain that pH or easily change in the presence of other chemicals.



Total alkalinity indicates how well a chemical compound will maintain its pH. To visualize this concept think about soldiers marching in formation. Let pH indicate how many columns of soldiers in the formation. The further from 7, the greater the number of columns. Alkalinity indicates how deep the columns are.

If something tries to change the pH, how much strength is in reserve to maintain the ranks? Some materials tend to stabilize a solution so that it maintains a specific pH. A buffered solution tends to resist a change in pH when acids or alkali are added. A cleaning solution that can maintain its pH in the presence of soil and other chemicals is said to be buffered.

Ingredients in a cleaning product that increase the total alkalinity are called builders. Builders may be added to buffer a product. Builders also help to counteract the effects of hard water.

The natural pH of most carpet fibers is near neutral (7). For wool, the natural pH will be between 5.5 and 7. For the life of the fiber and to keep from attracting soils, we should leave the fibers as close to possible to their natural pH when we have finished cleaning.

Scott Warrington

Wow Scott, that was awesome...even if it is long,lol.

You get an Atta boy on that one Scotty, You need to put on the white shop coat like Murry Crammer did, Kleenrite used that photo of Murry teaching the PH scale in their advertising for many years..

Just remember that each number is ten fold the last number in strength up or down on the PH scale...

KIS explaination

every number away from 7 is 10 times as strong, just like the Richter scale...a 9 on the Richter scale is 10 times as strong as a 8 on the same scale

Acidic and basic are two extremes that describe a chemical property chemicals. Mixing acids and bases can cancel out or neutralize their extreme effects. A substance that is neither acidic nor basic is neutral.

The pH scale measures how acidic or basic a substance is. The pH scale ranges from 0 to 14. A pH of 7 is neutral. A pH less than 7 is acidic. A pH greater than 7 is basic.

The pH scale is logarithmic and as a result, each whole pH value below 7 is ten times more acidic than the next higher value. For example, pH 4 is ten times more acidic than pH 5 and 100 times (10 times 10) more acidic than pH 6. The same holds true for pH values above 7, each of which is ten times more alkaline (another way to say basic) than the next lower whole value. For example, pH 10 is ten times more alkaline than pH 9 and 100 times (10 times 10) more alkaline than pH 8.

Pure water is neutral. But when chemicals are mixed with water, the mixture can become either acidic or basic. Examples of acidic substances are vinegar and lemon juice. Lye, milk of magnesia, and ammonia are examples of basic substances.

Here is a visual that might help- From my carpet cleaning manual-

Most earth dirt, foods, and other soils are acidic. A few are alkaline. Soils are generally removed by the opposite pH. Test all chemicals you have. Purchase a package of pH paper. Follow directions. Record the pH of everything you use, so you will know in the future. What pH means is the power of the Hydrogen ion. 7 is neutral, neither acid or alkaline.

Here is a visual chart that describes how pH relates to the numbers-

distilled 7.0 water (neutral)
weak acid 6.0/\8.0 weak alkali
mild acid 5.0/ \9.0 mild alkali
strong acid 4.0/ \10.0 strong alkali
powerful acid 3.0/ \11.0 powerful alkali
dangerous acid 2.0/ \12.0 dangerous alkali
very dangerous acid 1.0/ \13.0 very dangerous alkali

Two, and one on the acid side, twelve, and thirteen on the alkali side are corrosive to skin. Some others are, too. Many have strong fumes to be careful of. Always neutralize before applying the opposite.

Gary R. Heacock

That was great Scott,
If you dont mind I have a question. I use Chemspec products, and have been studying pH ballances. The prespray for a stain res. carpet should have a ph of no higher than 10, but the rence (formula 90) has a pH of 10 as well. So my question is how would I go from a prespray with the pH of 10 to nutral 7 ? thanks ...Sonny

A rinse with a pH of 10 will not return the pH to 7.

There are basically two types of products that can be used in the rinse. The first is an emulsifier. Usually the pH will be near to 10. The emulsifier gives a boost to the cleaning and also means you have a cleaner in the rinse to coer any areas that might not have gotten any prespray - for example under a piece of furniture that you moved.

The other type of product to rinse with is going to be on the acid side. It functions to reduce the pH and to rinse away detergent residues. This makes the carpet less likely to attract soil and often has a softer feel after drying. For some protectors, it is beneficial to have the pH close to 7 or even slightly less.

It is common to use an emulsifier with a higher pH on commercial carpets and trashed apartments and similar. No one is likely to be "feeling" the softness of a commercial carpet and maybe not applying a protector as often.

In a residence, the soft feel and the lack of resoiling is a bigger benefit. So acid side rinse are used here.

BTW- There are a couple of newer products that are actually acid side cleaning and rinse agents. They provide the best of both types of rinses. End Zone is an example of this kind of product.

Keep in mind that rinse agents are highly diluted - maybe 400 to 1. The effect of their pH is not as powerful as prespray which is not as greatly diluted.

Scott Warrington

Thanks for your help Scott...Sonny

Alkaline attracts acid, and vice versa. Most dirt soil is acidic, and alkaline detergents will attract it. The higher the ph, the more it attracts the soil.

People try to clean soil with vinegar, but vinegar will only work well on alkalline soils, not dirt. Vinegar is acidic, the opposite of a detergent, hence why it is good to use vinegar to rinse out soap. With soils such as urine, Vinegar will clean the alkaline salts from a carpet, but not the fatty residues. Alkaline salts hold moisture and promote odor, if removed, odor decreases, even if fatty residues are still int he carpet. Bacteria continues to thrive, but odor has decreased from removal of the moisture-holding salts from vinegar. This is why people think vinegar is good to clean up pee. They dont realize it only does half the job.

It does good to know the ph level of the soils you are cleaning, or attempting to clean. It is important to know that coffee is alkaline, and mud is acidic. Then you grab the opposite to clean it with.

PH isnt the complete answer to a cleaning solution. There are many high ph products that do not clean well, or can be hazardous to the material. Anything over a PH of 10 is very hard on carpets, especially natural fibres such as wool. But I have found ph 8.5 products that outclean ph 10.5 products. So there are other factors besides just PH. But Im not a chemist, so I cant explain emulsification and saponification, or the benefits of degreasing properties very thoroughly, perhaps Scotty can!

Am i correct on saying that just because a product says that it has a ph of say 10/12 that it will lower by the time it reaches the wand say to around 8/9. i read alot on chemspec web site and that is there claim. also ive seen some post on the (acidic) dirt, soil ect, what about everything else in our carpets? skin dander ,mites , soil, old cleaning products,dust. how does that affect what ph our cleaners wind up at?? this is a tough answer because every house has diffrent life styles , every part of every state has diffrent soils ect. not to mention water factors, is it all pot luck on what we get end results? is there a good middle point?to start at? mike.

Gentlemen;

Alot of great information above for everyones benefit. Consequently, since I have posted later on within this thread, I will only add one impoortant thing that I learned years and years ago when we used to do seminar demos. BTW, I believe that my good friend Gary H touched on this too:

The------strength---------of any acid/alkaline should always be seriously considered and is many times of even greater importance. For example without being too technical here, one capful of ammonia in 8-16 oz. water compared to two, three or four, may measure the same number on the scale; however, the a big difference in strength and perhaps performance.


Hope this helps;
Ed Valentine

Nice post Scott. Gonna print that out for a reference guide. Very helpful!!

For time and other reasons, IICRC courses do not allow for a detailed explanation of pH and everything related to it. The simplified explanations that are given can be misleading.

For example the question quoted above. If you mix a prespray with a pH of 10, 11 or 12 with water that has a pH of 7, does that bring it down to a final pH of around 8?

There are several other factors that must be considered when answering the question.

These include total alkalinity, buffering and concentration.

Since the prespray may be diluted with 8 or 16 or 32 parts of water for each part of prespray, it may seem that the final pH should be much closer to the pH of the water, 7. The concentration indeed does effect the final pH but not as much as one might think.

To help illustrate the difference between pH and alkalinity, think of of a group of soldiers advancing in a row across a field. Think of pH as the number of soldiers in that row. Is the row 7 soldiers wide? 10 soldiers wide? or 12 soldiers wide?

You might think that 12 soldiers wide is a "stronger" army than a group 7 soldiers wide. Just as we think that a pH of 12 is "stronger" than a pH of 7. But what is even more important is how many soldiers are behind each soldier in the front row. If a soldier is killed or wounded, is there someone behind to replace him?

That is total alkalinity. When something comes along with the potential to reduce the pH (mixing with water) does the pH decrease or not? If it does decrease, how much does it decrease? Those are the kinds of questions that require knowing total alkalinity and buffering.

A product with very stable pH is said to be buffered. Whatever you add to or dilute a buffered product with does very little to change the pH. It stays at whatever it was even when diluted with water in cleaning solutions.

One place this is important is when cleaning natural fibers such as cotton upholstery or a wool rug. Here is a real life situation.

The pH of wool AFTER cleaning should be left neutral or slightly acid, between 4.5 and 7.0. Some have said, that means wool should always be cleaned with products that have a pH of less than 8 (or some other number).

If a product with a pH of 8.0 was buffered and had high total alkalinity, it could be diluted and rinsed and still have a pH of 8! This could be harmful to the wool.

Another product with a pH of 10.0 when concentrated is not buffered. After being diluted, the pH drops. When rinsed with water or an acid rinse agent, the pH drops further. This product might break the "rule" never to clean with a product whose pH is above 8., but it ends up leaving thw wool at a pH of 7.0 when the cleaning is done.

Some organizations have done extensive testing on this subject. The point is that the pH of the fibers after cleaning is much more meaningful than the pH of the chemical you use to clean. You may benefit from taking pH readings of carpets or upholstery fabrics after you clean to determine more closely how your choice of products and procedure effect the final pH.

Scott Warrington