Following is an extract of a post by TAYYAB should be more than enough to please you
What is Claybar?
Claybar is a bar of claybar which is chemically treated to remove above surface bonded contaminants, like oxidation,industrial fumes etc.
How much Claybar needed?
1.That depends on the condition of your car's paint.How have you been washing the car?Have you been waxing it?Is it exposed to dust too often?.For instance, if a 3 years old car hasn't been waxed since day one and washed by the service stations, then it may need one whole claybar or two claybars.Usually, it happens when you claybar on a really dusty car, the claybar completely gets filled with dust and you have to replace it with a new one.Using the same dusty claybar can cause scratches because the dust granules which has been taken off by the claybar will scratch the clear coat.
How to use it?
2.Claybar is not wet at all.It is a bar of clay treated with chemicals to pull of the toughest dirt or grime.To make the claybar wet,a detailer spray is given.You need to spray the detailer spray on the claybar as well as the panel you are working on.Once both the things are wet,you start doing claybar on the panel.
WARNING: If you happen to drop your clay bar, dispose it and not use it again.The dirt from the ground will stick to the claybar and will result in severe scratches if applied to the panel you are working on.
Claybar actually cleans the paint.You asked about Cleaner Waxes,they also do the same job as a claybar.The only difference is cleaner waxes are abrasive.
After you claybar the whole car,you can wash it to remove any residue and proceed to the next stage.