Detailing Chemistry 101

Summary: A short introduction into what makes cleaners clean, mostly meant as a starter for your own further research.

What makes a cleaning chemical clean 

Let’s first recap the basics:

One of the biggest ground rules in cleaning theory is Sinners Circle/TACT. Which means that cleaning mostly consists of these four general components 

• Temperature (a hot rinse is gonna do more than a cold one, a warm shampoo water shampoo is gonna clean better than a cold one…)
• Agitation (A Scrub Ninja cleans more than a towel and a towel cleans better than no agitation)
• Chemical (a just water rinse cleans significantly worse then applying an APC or alkaline pre wash and then rinse)
• Time (check this yourself with a pH neutral soap, the longer it stays on the better it cleans – also goes for doing multiple rounds with a milder chemical vs one round with a heavy one) 

Now that we have gone here let’s talk about the chemical part as in very simplified what makes a chemical even clean. 

Let’s first talk about the one that most people use – pH.

A quick recap: pH is a decadic logarithmic scale that tells us about the activity of protons in the solvent (in our case for the most part water) 

In watery solutions pH goes from 0-14 with anything below 7 being an acid  and anything above 7 a base/alkaline and 7 being neutral. 

For our detailing concerns pH mostly tells us two things.

For one we always have to watch out for the extremes, as anything below pH 2 or above pH 12 is generally considered unsafe for coatings. Apart from that, extreme pH products have their uses if you know how to work with them and take the necessary precautions- always read and follow the SDS!) and can be used especially on “disaster” details.

So what is the second thing to learn about pH in detailing? 

It’s an enabler. An alkaline Product will never be good at removing waterspots for example.

A general rule of thumb is that alkaline products work great against organic residue (bugs, road grime, to a point tar and sap) while acidic cleaners do well against inorganic dirt, e.g. mineral residue and iron contaminants hence why you will find a lot of acidic or even lightly acidic wheel cleaners (“pH skin neutral” being a famous marking name for pH 5.5 cleaners). 

To recap: The pH tells you what a product potentially is capable of doing, but does not give a great indication on how well it will do something as this is just one factor of many, a few of them we will list here today.

Earlier I said I will tell you two things about Acidic/Alkaline cleaners. I lied. Here’s the third one:

No acid or base is similar to another. The way you reach the concentration of protons that gives you said pH matters. All of these have many more things they do, and all of those matter. There are oxidizing and reducing acids and bases, chelating agents, buffered solutions, and much much more. This field is extremely complex and really beyond regular grasp if you haven’t been involved with the composition of that specific product. All of these can be tensides too for example. There are even more considerations to be made – for example things like the hard and soft acids and bases theory,  but that is far beyond what we can consider here. 

Lastly a little reminder: For an optimal solution that is not buffered and only contains strong acids or bases you can calculate the diluted pH roughly in your head. Every time you dilute x10 pH moves one grade more towards 7. So let’s say you have a pH 11 product that you dilute 1:100, you end up with a pH 9 product.

Let’s move on to the solvent part.

Solvents can be described in many ways, I will go with the “standard” description from organic chemistry. Solvents can be classed into protic and aprotic solvents. Protic means the solvent can do funky stuff with protons, which we learned earlier are important in acid and base chemistry. Examples are Water, but also solutions of pure ammonia or pure acetic acid for example. You can think of most non tar/sap removers as protic system, where acids and bases work for the most part as they would in water.

Secondly we have to consider polarity. 

Polarity means if the molecule has poles (Imagine them like places where electric charge accumulates or there is a lack thereof)  that are more electron rich or electron less.

Polarity is a scale, but there is no accompanying values like there is for the pH, you just have to know what to look for.

Polar solvents and unpolar solvents can be mixed with the help of tensides or other emulgators. This is a big basic part of cleaning.

Generally speaking unpolar solvents can help with some organic dirt but can also be bad for paint, gaskets, plastics,… 

Most truly unpolar solvent based products you will find are tar and sap removers, panel preps and some old school polishes and most coatings. However many other products have a unpolar solvent component. E.g. there are APCs and strong pre cleaners that are both alkaline and have a solvent component that leads to very strong cleaning of organic dirt but also leads to (depending on the solvent) material safety concerns.

Most importantly for most cleaning jobs are tensides.

Tensides allow for polar and unpolar molecules to mix, they in a very simplified way have two ends, one is polar one is unpolar in most cases and that allows them to form a bubble around the the solvent droplet and allows them to carry and suspense the dirt, too. They also depending on which you use (and most of the time multiple ones are used to achieve a wider ranging cleaning) foam or don’t foam and provide lubricity. They also lower the surface tension of the water, allowing a good soap to stay flat on otherwise beady paint.

Tensides for the most part can be classified in four categories:

• cationic (positively charged) Tensides
• anionic (negatively charged) Tensides
• Zwitterionic ((both positively and negatively charged functional groups on the same molecule) Tensides
• No ionic Tensides that don’t have an anionic or cationic functional group.

All of these do very specific things, but that is something for a further expansion of this article.

Tensides are where a lot of the magic happens and most of them won’t ever show up in an SDS, they can make or break a cleaner. 

There also are other things and chemical reactions at work during cleaning. Color changing Iron removers for example work by forming a complex with iron ions that chemically binds them and removes them from the surface. Some cleaning chemicals do react with the dirt.

But for now, this is where we stop until a potential detailing chemistry 201.