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I've seen a number of mentions of "claying" before polishing, with some people swearing that it's an absolutely necessary step before polishing, while others seem to get good ( or at least pretty decent ) results without this step.

But for a normal car, with not perfect, but decent paint ( some nicks, some oxidation, but hasn't lost it's clear coat yet ) how recommended is this step.

I'm not talking about taking the car to a show, just wanting it to look what you might call "normally" good without it taking 10 hours to complete.

And of course, exactly what is "clay" and specifically, from a technical point of view, why and when is it recommended?

  • I was also curious if by "polishing" you mean just cleaning/waxing, or if you mean actually using cutting/polishing compound to cut the clear coat and take out the imperfections? – Pᴀᴜʟsᴛᴇʀ2 Jul 11 '16 at 20:50
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It would be silly to skip claying if the paint surface is heavy with contaminants and go to the compounding/polishing step; it would be like using makeup to cover blackheads - the right thing to do is remove the contaminants and work off a clean surface.

Compounding uses micro-abrasion to reduce the visibility of paint imperfections while polishing works by "filling" regions of imperfection with wax (usually temporarily). They are not designed to work with the presence of surface contaminants and will do little to mask them.

Also, note that clay mitts and clay towels are available as alternatives to clay bars. They give 95% of the result with none of the usual drawbacks. Plus it's far quicker to clay a car than compound/polish it. For a mid-size sedan you should need no more than an hour.

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tl dr: It isn't necessary, but it improves the quality of the polish/wax job.

"Claying" (otherwise known as using a clay bar or detailing clay), is a means by which to remove contaminates from the finish of your vehicle which washing alone will not remove. The clay bar creates a shearing action, which basically cuts the contaminates off of the clear coat, then encapsulates the contaminate so as to not create damage to the finish. When done, the finish is more ready to receive polish and/or wax.

The clay bar itself is pretty much what the name implies, though it's not made out of organic or natural stuff, but more-so is a synthetic (man made) clay specifically designed to do what it's designed to do: remove paint contaminates. A typical bar of clay comes wrapped up like this:

enter image description here

They can come in just about any color. When you first pull the clay out of the wrapper, you need to knead it, as in, fold it back on itself and get it more malleable. When actually using it, you need to also use a lubricant with it to ensure it isn't sticking to (or grabbing) the clear coat in the process. Here is an image of what it kind of looks like when in action:

enter image description here

The contaminates are stuck to the clear coat, while the clay bar comes along and intercepts them, absorbing them into itself. To do this correctly, you need to continually fold the clay bar back on itself to further encapsulate the contaminants inside the clay bar. When in use, the clay bar will look like this, and is how you'll know it's working:

enter image description here

You work a small part of the car at a time, ensuring you are keeping the clay bar wet and the lubricant present at all times. If you should EVER drop your clay bar to the ground, get a new one, as the contaminants from the ground can cause big damage to the finish on your vehicle.

You should wash your car prior to using a clay bar so as the clay bar is only picking up contaminates from what is stuck to the finish and not everything which is on the vehicle prior to. It should be a noticeable difference after using a clay bar, especially after waxing/polishing. As was stated, it isn't necessary, but it does make the finished product look that much better.

PS: You can clay bar your windows as well to improve optical clarity.

  • Good instructions. I'm wondering if wearing disposable medical-type gloves would be a good idea to protect both your skin and the clay? Also, what kind of lubricant exactly? – Basil Bourque Jul 12 '16 at 0:10
  • @BasilBourque - Gloves aren't needed, but you can feel free to do whatever you like. As for lubricant, most clay bars only call for water. Some manufacturers have their "special" spray, but I wonder what it really is. Just follow the manufacturers directions as far as what to you. Usually if a clay bar requires a special lubricant, it is purchased at the same time as the clay bar. – Pᴀᴜʟsᴛᴇʀ2 Jul 12 '16 at 0:40
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    It seems useful to mention that a) If the paint is already smooth to the touch, claying it won't change anything, and b) Most clay lubricants are exactly the same as detailing spray, which can be made from concentrate for a fraction of the cost. A product called "Optimum No-Rinse" is one example of that concentrate. – Lathejockey81 Jul 12 '16 at 2:04
  • When I say polishing in my question I mean real polishing with compound and a polisher. Then a separate waxing step afterwards. – Robert S. Barnes Jul 12 '16 at 4:09
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    @RobertS.Barnes - In that case, I'd highly recommend doing the clay bar, as you'll be swirling all of those contaminants into the clear coat as you are trying to cut a clean surface. Would not be pretty. – Pᴀᴜʟsᴛᴇʀ2 Jul 12 '16 at 10:54
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The actual polishing is a very sensitive thing, basically it is a wax containing a light abrasive compound, which is softer than a clear cote. Waxing is to put an extra coat of wax on a car which will fill the micro scratches and will look shiny. Polishing - it's a rubbing off a micro coat of clear cote, and in same time get the surface totally flat and shiny, and plus it will leave a wax on a surface. A good polishing will need a proper polisher (big angle grinder, only with about 800-1000RPM), and polishing waxes. To me the best known and enjoyable stuff is 3M. Must be very careful with sharp corners and edges. I never heard about "claying", I always cleaned it off with a polisher, maybe I should try :)


For a beginner I would recommend some kind of T-Cut kits which is designed for beginners, contains very fine abrasives, good wax, and polish it by hand. If you need more polishing, ask any experienced person to help, so he can actually show and explain.

  • Not all polishes contain wax. A true polish will not contain any wax. – Evan Parsons Jun 26 '17 at 14:35
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Yes it is necessary to clay a car before compounding/polishing. It is far better to do it and not need it than to need it and not do it. Lets pretend your car does not have any microscopic issues in the clear coat/paint. First that would mean you have never driven the car, since it is almost a 100% guarantee this will happen after the first drive. Next, if it truly does NOT have any contaminants, what have you lost? An hour of claying? However, I doubt, wholeheartedly, that there is a car out there without contaminated paint.

If you don't you could pick up those contaminants with the buffer and use them to mark the living hell out of your paint.

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