For the next few issues I am going to be writing a series of articles on the science of cleaning. We all know which cleaners work and which cleaners don’t work but we don’t always know why. We often learn through trial and error. Understanding the science will help us understand if a new cleaner will deliver on its promises without risking damage to a customer’s home. Also the ability to explain why a product works separates us from our competition by showing that we are true professionals with training and knowledge. In fact the topic of today’s article, acids and how to use them, was the reason I won a large contract as the sole cleaning contractor for an apartment complex with over 450 units.

Most people understand what an acid is even if they don’t understand the technical definition. However understanding the pH scale is important because it tells you how strong an acid is. The pH scale goes from 0 to 14. Any chemical that has a pH less than 7 (when dissolved in water) is an acid. The lower the pH number, the stronger the acid. The pH scale is logarithmic which is a fancy way of saying each point on the pH scale means the acid is 10 times stronger than the next number on the scale. So a cleaner with a pH of 1 is not slightly more strong than a cleaner with a pH of 2, it is 10 times stronger.

Acids are very useful in cleaning, especially in bathrooms. Soap scum has many things in it but in most cases it is calcium or limestone which is dissolved in tap water. As the water dries on the bath walls it leaves behind a small amount of limestone and calcium which builds up over time. Soap scum is not soap at all, in most cases it is a layer of stone made up of these two ingredients on the bathroom surfaces. This is why it is so hard to remove with normal cleaners. It is like trying to clean a rock and wondering why it is still a looks like a rock after you scrub it. The only really effective way to remove soap scum is to use an acid. Acid will dissolve the soap scum into liquid or a gas. Think of your elementary school volcanoes. Vinegar is an acid (pH 3) and when mixed with baking soda the baking soda is dissolved and/or turned to a gas. Acids do the same thing to soap scum. This is also why you need to leave soap scum remover on the surface for a while before you remove it. You need to give the acid time to work. This is also why most toilet bowl cleaner are acids. Acids remove those hard water rings and rust, although rust is whole other discussion.

While acids do a great job removing soap scum they also will damage chrome. Most bathroom fixtures are chrome plated because chrome is a very durable and water resistant product. However chrome has one very serious weakness, acid. Acid will eat the chrome plating. The stronger the acid and the cheaper (thinner) the chrome plated fixture, the faster this damage will occur. It is very important that you understand the pH level of your cleaner because they all say they remove soap scum but the lower the pH the better the job it will do removing the soap scum but also the more likely the product will damage chrome. All bathroom cleaners make claims like “powers through soap scum” but these claims don’t really tell you anything. The pH of the product does not lie. The best way to learn the pH of any product is to go online and get the MSDS sheet which will tell you the pH of the product. Below are a few examples of common cleaners used by residential cleaners and their pH:

Comet Bathroom Cleaner – pH 3.0 (active ingredient citric acid)Lime Away – pH 2.0 (active ingredient phosphoric acid)Works Toilet Bowl Cleaner – pH less than 1.0 (active ingredient hydrochloric acid)

Remember the pH scale works on factor of 10 so Lime Away is 10 times stronger than Comet Bathroom Cleaner and Works Toilet Bowl Cleaner is 100 times stronger than Comet Bathroom Cleaner. If you have ever cleaned a really nasty bathroom with years of soap scum you have probably used a toilet bowl cleaner on it and seen how it eats the scum right off in seconds. If you got the cleaner on the chrome you also probably bought your client some new fixtures.

So back to my story from the beginning. I was called to bid on cleaning apartments and common areas for a complex with over 450 units. The previous company had been doing a great job cleaning the units but they kept damaging the chrome in the kitchen and bathroom. The owner of the service kept trying different cleaners but she kept having the same problem. When they told me this I explained the reason why this was happening was because the complex was using very cheap fixtures with super thin chrome plating. As a result even very low acid cleaners (like Lime Away and CLR) that were safe in 99.9% of residences would damage their chrome. The solution was to either buy a better fixture (no chance) or to make sure we only used cleaners with a pH higher than 3 on chrome. When I explained this to them I won the contract right then and there. They had been spending thousands of dollars on new chrome fixtures and sinks. I was able to explain to them not only how I could fix the problem but I also helped them make a list of cleaners which they could give to the residents to use. This separated us from all the other bidders (that had no idea what went wrong) and the owner of the previous company that by all accounts did a great job and tried every cleaner in the grocery store but could not make the client happy.

Derek Christian is the owner of My Maid Service with offices in Cincinnati and Dallas. Prior to purchasing My Maid Service, Derek spent 12 years working for Procter & Gamble, the world’s largest consumer products company. Derek is on the Board of Directors of the Association of Residential Cleaning Service International. For more information on ARCSI and Derek go to www.arcsi.org or www.mymaidservice.com