Join Date: Nov 2001
Location: San Francisco
Ferrari Life Posts: 6,320
Here is an article.
Using a Clay Bar on Automotive Paint
Contaminant removal with the detailer's secret
By: M. Justin Fort/autoMedia.com
Wash your car and look closely at the paint surface. Run your finger across it. If this finish is anything less than pristine, you're going to notice things with your finger. Things on the paint surface that aren't visible but still there, stuck to it, embedded, adhered to the paint in a fashion that keeps these particles from being removed by a typical washing.
What's happened is the sharper, pointier, stickier things in the air have actually jammed themselves into the first layers of paint. This is no longer a surface-only dirt issue that a thorough washing can handle, as a wash mitt or sponge doesn't have the grabbing, grippiness to pull these things out. So, you're left with a clean car that's still covered with the same selection of glass fragments and fibers, rail dust (little metal slivers emitted by the interaction between train wheel and rail), minute chunks of gravel and Earth byproduct. Enter the clay bar.
We can hear you asking what clay has to do with car washing. Imagine this—the act of pulling a soapy sponge across your car's wet surface while washing, with the stiction capacity (just made that up; the degree to which something adheres to and pulls on a surface when interacting with it laterally) amplified to where the pulling and stiction level is great enough to remove minute contaminants embedded in the paint. That's what a clay bar does: cleans the paint surface down to its pure paint self, sucked clean.
Automotive paint clay is a very particular grade of fine clay, not too unlike some clays used in modeling. Used by car care pros for ages and long a back door secret of the car care industry, insiders have brought the clay bar and its usefulness to public attention. Used with a lubricating spray (often a detailing spray) that allows the otherwise super-tacky clay to glide without marring the paint itself, automotive clay can be the tool to step from "just washed" to "ready to polish and wax."
Using clay is remarkably simple. Starting with a freshly cleaned vehicle, wet a section of the vehicle's painted surface with the clay lubricant and rub the clay on the paint in a random fashion. You don't want to use the whole wad of clay—a half or a third of what you're supplied is a good place to begin. As you use the clay, "rotate" it frequently, turning it as it fills with the things it pulls from your paint. You want to have fresh clay touching the paint. Dry off completed portions of paint with a cotton towel. Again, work by sections. Important: listen to the clay. As it slides across the paint on a film of lubricant, you'll hear its contact with the bad things in the paint. As fewer things are left to pick up, the bar will make less noise and you'll feel it slide more easily. You can treat the whole vehicle this way. Run your fingers across the paint after working over a portion of the painted surface and you'll be able to deduce the difference, by touch.
Don't forget to use plenty of lubricant. Too much can be mopped up with the towel. Using too little risks allowing the clay to scratch your paint. Late-model paints have a much softer composition than older enamels, so misuse of a clay bar will show readily, so use plenty of detailer. Clay can also be employed to clean hard plastic surfaces, trim, chrome and water-stained rubber in the same fashion as it does paint. The friction coefficient is not the same as with paint, but properly lubricated, the clay works wonders on these surfaces. Paint overspray can be removed from almost all automotive surfaces with clay, too. Note that clay can strip wax from paint, so be prepared to re-wax the vehicle's surface after using clay on it. Some clays are harder than others and leave less margin for error between effective lubrication and not enough. If the clay lubricant/detailer dries on the paint surface, a further spritz will let you wipe it off.
Clay bar treatment kits are available that provide you with the necessary lubricant and enough clay to do plenty of paint, multiple cars worth. Some kits come with a sample of wax, too, to give you a chance to test one manufacturer's formula of wax.
If you've never clay-barred your ride, take a moment to run your hand across the paint. The little things will be there, stuck to it, waiting for you to take action. C'mon—a little stiction never hurt anyone.