Detailing Clay & Pre-wax Cleaning, Extensive How-To

This is a repost from Autopia. Is is the best how-to and write up I've found on this crucial and misunderstood part of the exterior detailing process.

Every car finish shares a common enemy: pollution. It relentlessly pursues your car from the second it leaves the factory until your car meets its ultimate demise. It's in the air we breathe, it's on the roads we drive, and it attaches to your car's paint, where it bonds and begins a process of oxidation. When contaminants get a solid grip on your car's paint, washing alone may not be enough to remove them. Pre-wax cleaners also may not be able to exfoliate large particles. In this case, you have two choices: use a polishing compound, which removes a lot of paint material, or use a clay bar. Clay isn't a polish or a compound, it is a surface preparation bar that smoothes the paint and exfoliates contaminants.

USES FOR CLAY
Clay is not a cure-all or a replacement for polishing. It's a tool for quickly and easily removing surface contamination.
One of the many reasons for using clay is the removal of brake dust. Brake dust contamination, which attaches to painted rear bumpers and adjoining surfaces, is a metallic surface contaminant that can be removed safely and effectively by using clay.
Clay is also very effective on paint over-spray. If the over-spray is particularly heavy, you may want to seek the assistance of a professional. Tree sap and tar specks can also be safely removed with a clay bar.

Recently, I have also started using clay on my windows (exterior) to remove heavy road film, bug deposits and water spots. It works very well, and seems to outperform even the best window cleaners.

HOW DOES DETAILING CLAY WORK?
I frequently see detailing clay marketing information that reads something like this: "clay pulls contamination off of your paint..." This statement sounds pretty ridiculous when you realize that you must lubricate the surface you're cleaning with the detail clay. How in the world do you pull on something that's wet and slippery? This myth was born from a fear of telling people the truth. Clay is an abrasive paint care system. Yet used properly, detailing clay is not abrasive to your car's paint; it is abrasive to paint contamination.

Detailing clay is an abrasive system. If not used properly, detailing clay can cause light surface marring. There's no need to fear if you use proper lubrication.

An easy way to think about detailing clay is simply this: detailing clay is a "selective polish" with a built-in applicator. Its job is to polish away dirt and surface contamination from paint, glass, chrome and plastic without polishing the surface itself. A pretty simple concept, isn't it? Detailing clay technology has been around for many years, with roots dating back to the 1930's. That's when the idea of combining polybutene (a soft plastic resin material) with abrasives was first put to paper.

Enough with the techno-speak; how does detailing clay really work? What I learned from my research and speaking with experts is simply this:

* Detailing clay works by hydroplaning (floating) over the surface you're cleaning on a thin layer of clay lubricant.
* When the clay (polish) encounters surface contamination, it abrasively grinds it away.
* Detailing clay shears off any foreign material above the level surface of the paint.

Those are scary words to a car enthusiast, but it's an accurate description. You can see the end results of this grinding work by inspecting your clay. Does your clay have large particles sticking to it or does it have what appears to be a dirty film? It's the latter, of course, and it's proof that your clay is doing its job gently polishing away contamination.

You may be wondering if the different colors of clay are really all that different. The answer is yes. As it turns out, there is a lot that goes into each formulation of detailing clay. Although most of the clay made today comes out of a single factory in Japan, the formulas can be significantly different, including:
* Clay resin density (firmness)
* Abrasive particle size
* Type of abrasive
* Abrasive density (ratio of abrasive to clay)
* Color

Detailing clay formulation determines the optimal function of the clay and its potential to do damage when used improperly. As an example, professional grade clay that's designed to remove paint overspray is very firm and contains abrasives equivalent to heavy rubbing compound. Used properly it will remove heavy overspray without damaging the paint. Used improperly, it can leave some pretty significant surface marring. That's why it's a professional product.

Most consumer grade detailing clays are designed to be used as an annual or semi-annual paint maintenance tool prior to polishing and waxing. At this frequency, these detailing clay products work great. Simply use the clay as part of your major detailing regimen. The problem we were beginning to see is that many car enthusiasts wanted to clay their vehicles frequently; as often as monthly. At this rate of use, some consumer grade detailing clay can begin to dull clear coat finishes. After all, it is an abrasive!

EVALUATING YOUR PAINT FOR CLAY
How do you know if you need to use a clay bar? After thoroughly hand washing your car, feel the surface of your car's paint. Do you feel bumps and rough spots? These bumps are contaminants attacking the finish of your car. Removing these surface contaminants (road tar, acid rain spots, bug residue, paint over-spray, brake pad dust, hard water spots, etc.) will improve both the look and health of your car's paint. By the way, you can magnify your sense of touch by inserting your fingertips into a sandwich bag or a piece of cellophane.

No matter how well you hand-wash your car, many of the contaminants that have worked their way into your car's paint finish will remain. Have you ever looked at your foam wax applicator pad after applying a coat of wax? What do you think that black stuff is? It's dirt, and you're waxing over it, sealing it in.

CLAY SAFETY
Detailing clay isn't new. Paint and body shops have been using it for years to remove paint overspray. Clay is fairly new to the car detailing market, and is very new to the consumer on retail shelves.

In the early days of detailing clay, there was a concern that paint damage might occur if improperly used. These concerns have been overcome through proper education and product improvements.

New technology detailing clay bars are made of fine polishing particles in a soft, malleable "clay" medium that allows the bar to be formed and kneaded. Some clay makers add color to make the bar more attractive or to identify bars of differing strength (coarseness).

Many clay products claim to contain no abrasives. This is stretching the truth. The reason clay manufacturers claim their products don't contain an abrasive is because the general public thinks the word "abrasive" refers only to aggressive, paint removing materials. The fact is that the abrasives in most automotive clay products are so fine that you will not see any reduction in paint gloss. After several uses, paint luster may even improve.

Still, I have heard some horror stories about people ruining a Ferrari paint job using a clay bar. I can see how this might be true if an inappropriate product was used or if the clay bar is used incorrectly. The critical component to safety is proper lubrication.

Most clay retailers recommend using their detailing spray as a lubricant. Detail sprays work as a clay lubricant because they contain chemicals that prevent scratching when wiping away dust and light dirt. The problem is that most detailing sprays also contain some form of alcohol. Used in heavy concentration (the surface must be thoroughly wet with lubricant), alcohol removes wax protection and causes most clay formulations to break down and get mushy. Once this happens, your clay is dead, and it will make a smeary mess. We also discovered that some car wash soaps will cause the same problem when the clay is allowed to sit in the bucket of soapy water.

USING CLAY
Using clay is very easy, but you must follow the instructions. Use clay incorrectly and you will create a mess or scuff the surface of your paint.

Before using detailing clay, you must thoroughly clean and dry your car to remove any loose dirt. Direct sunlight should not fall on your car's surface, and it's best if the work area is relatively cool to prevent rapid evaporation of the clay lubricant.
To use the clay bar, you spray a lubricant on a small area of your car and rub the clay back and forth with light to medium pressure. If the lubricant begins to dry, you'll need to spray more. Clay is fairly sticky and cannot be used dry. Try using clay dry and you'll make a big mess and scuff your paint.

After a few passes with the clay, rub your hand over the area you cleaned to check for areas missed. You should feel a distinct difference between the areas you have clayed and the areas you have not clayed. Keep rubbing until all contamination bumps are gone. Finally, wipe the clay residue off with a soft microfiber towel, and buff to a nice luster. Just like waxing, work in small areas.

Check the clay bar frequently for hard particles. When found, pick them off. Make it a habit to occasionally knead and reform the bar so that a fresh portion of the bar contacts your car's paint. If you drop your bar of clay on the ground, it's history. Toss it out. Don't take any chances, discard the clay bar if it becomes impregnated with grit. Read the manufacturers' directions for the number of uses of their clay bar. Do not overuse a clay bar.

When you're finished claying your car, you should wash it to remove the lubricant film, then go over it with a pre-wax cleaner to finish cleaning the paint. Finally, seal your freshly cleaned paint with your choice of wax or sealant.

OTHER USES FOR CLAY
Clay isn't just for paint. You can use detailing clay on any smooth, hard surface, including glass and chrome. Do not use clay on clear plastic, such as headlight lenses.

When I can no longer remold clay to get a clean surface, I retire it for use on my windows. The dirty clay will not harm glass, and it's amazing how much dirt film clay can remove from your exterior glass.

I also use my old clay to clean wheels. Clay will safely remove stubborn, embedded brake dust, tar and road film from all factory wheels. Clay is not recommended on wheels that do not have a factory clearcoat or powder coat finish.