Originally Posted by detailwerkz.com

To work with clay you will need a lubricant. Fortunately what you use is not critical and many products will work fine. Many clay kits ship with a "Quick Detailer" spray which works. I use a tablespoon of car wash detergent (dawn) in about 20 oz. of distilled water and dispensed using a spray bottle.

The "baggie test" is the way to go and is recommended as an easy way to demonstrate the power of claying. Put your hand in a ordinary sandwich baggie (the thin kind, not the thick rugged ones) and spray a test area of the paint with the above described clay lubricant. Then go over the paint surface as shown with just enough pressure to get a feel for the surface. You'll detect all sorts of bumps and defects, many more than are apparent with even a close visual inspection.

Claying is done after the car is washed, but before it is waxed or polished.

To use the clay, apply some of the clay lubricant to the area you are going to work on, which shouldn't be larger than about 2' x 2'. Then glide (in other words, use only minimal pressure) the clay over the surface. If the lubricant is working, the effort to move the clay over the surface will be next to nothing; you are really guiding its movement more than anything else. A lot depends on how much the clay has to pick up.

As you progress, you'll note that the clay bar gets thinner. You'll then have to rework the bar so that it is thick again by kneading it. I like to just fold it over, the reasoning is that it will have a cleaner surface. You'll get a feel for how it is working by the way it glides over the paint surface. This "feel" will also tell you when the clay bar is losing its effectiveness (it's resistance increases) and needs to be replaced. When you are finished with a section, dry it using the same towels you use after you wash the car. It's a good idea to re-wash or heavily rinse the entire car with a hose after you are finished with the claying task. When you are finished, do the "baggie test" again. The results will be easily felt.

A clay bar is good for about four to five treatments. This depends on factors such as the size of the vehicles and how dirty they are. One important note: if you ever drop a clay bar, you MUST throw it away. The potential for causing scratches from material it picks up is just too great. If you intend to reuse the clay bar, store it in a box or baggie to keep it clean.