They are made to be used over and over. They are clay.....You keep kneading it until you can find a good clear patch. Eventually this will become impossible and you replace it......
Both of these answers are 100% correct. Here's a writeup that I did on claying which may help in bringing some clarity.
What is the clay bar process, you ask?
Clay Bar is used to remove paint contamination, overspray and industrial fallout.
What is paint contamination?
Paint contamination consists of tiny metal shavings from rail dust, brake dust and industrial fallout. This contamination affects all paint finishes and can cause serious damage when left untreated. Paint contamination can be felt as a "rough or gritty" texture on the paint's surface and can lead to tiny rust spots. This contamination can not be removed by washing, waxing and/or polishing. Check out the three stages of paint contamination.
Stage 1:
Metal shavings land on the paint's surface.
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Stage 2:
Shavings start to oxidize.
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Stage 3:
Rust spots forms in the paint.
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Where does it come from?
There are three major causes of paint contamination:
1. Rail dust - produced from the friction of train wheels against railroad tracks. Over 70% of new vehicles are shipped by rail. Rail dust can contaminate a new car's finish before it even reaches the dealership. Anytime a vehicle is parked or travels near a railroad it is subject to rail dust contamination.
2. Brake dust - particles produced from the friction of brake pads rubbing against the rotor. This metal on metal friction disperses tiny particles of bare metal into the air and on the highway where it collects on passing vehicles.
3. Industrial fallout - another word for pollution, industrial fallout is a byproduct of our modern industrial age.
Testing for paint contamination:
After washing and drying your vehicle, put your hand inside a plastic sandwich bag and lightly run your fingertips over the paint's surface. It should be as smooth as glass. If your car's surface has a rough, gritty or pebble-like texture, it indicates the presence of paint contamination. This should be removed with a clay bar before applying a polish or wax.
Removing Paint Contamination:
There is no wax, natural or synthetic, or any chemical treatment that can prevent or protect against this contamination. Compounding with an abrasive polish may remove paint contamination but it can only be performed a few times before removing too much of the top, clear coat finish. This is why the process of claying is required. Claying removes these impurities without removing your clear coat. It is the safest, most effective way to do so.
Claying is a simple process, although you may have to exert a little energy. The secret to proper claying is to keep the area that you are working on
wet at all times. Not doing so makes the claying process difficult and it also causes marring of the paint. The amount of pressure that you apply is directly proportional to how bad the paint is contaminated. A 10 year old car that has lived in a driveway all of its life is going to require a little more scrubbing than your new car that you have just driven off the car lot.
The object of claying is to get the paint as smooth as glass. Work in small sections (1 foot square areas). Once you get a section smooth as glass, you move on to the next section. Work in small areas so that you don't miss anything. Here's a short video of me claying an area of a bumper in which a deep scratch resides.
The Claying Process Video
The claying process itself does absolutely nothing to remove swirls or scratches. It simply removes the impurities from the paint as stated before. Claying is a very important process
when necessary, and contributes effectively to obtaining that deep, glossy shine.
When should I clay?
Only when your finish fails the baggie test described above. Some folks clay their finish too often. It is not a set in stone step with paint maintenance, it is only required if your paint needs it. A car that stays garaged, covered and not driven often is not going to get clayed as often as a car that sits in a driveway night and day, in a dusty or dirty environment. I have personally clayed my car once, a year and a half ago. It of course is the first car in the scenario above.
Performing the claying process in the shade or indoors helps keep your lubricant from drying to quickly. Try and do so if possible.
The Junkman
