Bilt Hamber Auto Clay Regular Review

Bilt Hamber Auto clay regular is a market leader in the field of clay bars.

We bought and tested Bilt Hamber auto-clay to put it though it’s paces.

Short summary: it’s good. Bilt Hamber Auto Clay efficiently removes embedded contaminants from the surface of paint, allowing for machine polishing to be carried out without risk of the pad becoming clogged with contaminants.

Read on for details on where it performs, our testing criteria and details that show you how to use Bilt Hamber Auto Clay like a pro would.

Prepmycar Rating: 8 / 10

Bilt Hamber Auto Clay Bar Regular 200g

Bilt Hamber Auto Clay Results

  • Contamination Removal
  • 7  Abrasiveness
  • 9 Form
  • 7.5  Marring
  • 7.5  Ease of Use
  • 8.5 Value For Money


For many years, clay bars were the detailer’s secret. They were sold to professionals; ordinary car enthusiasts were unfamiliar with their function.

In the last decade, this has changed, with mainstream brands producing clay bar kits for the consumer market. Bilt Hamber Auto Clay is one of the best that I’ve tested to date.

Bilt Hamber Auto Clay Regular is an abrasive clay bar that will removed deeply embedded contaminants. It offers great value for money and is one of the best clay bars for pro and enthusiast detailers alike.


  • Abrasive clay bar that will remove deep contaminants
  • Very good value for money and cost-effective
  • Durable so will last a long time
  • Water is used as a lubricant so no additional costs


  • Can be overkill for a lot of cars that are regularly maintained
  • Will cause marring if over-used

Testing Process

Auto-clay is a product I am very familiar with and has been my go-to clay for over two years. A common mistake that is made with clay bars is that users do not tear a small bit of clay off the bar, which makes the clay very unwieldy.

When I buy a new clay bar, I cut the bar into small sections, roughly 4 cm x 4 cm x 0.5 cm. I then wrap the small sections in greaseproof paper and then store them in the box. That way I do not need to tear bits of clay off the bar during a detailing job, I can just a small pre-cut section. This is also a more efficient way of using clay, as more surface area will be able to be used by cutting the block into smaller chunks. This also means if I drop a piece of clay, I only need to throw away a small amount, whereas if I were using a whole clay bar at a time, I would have to throw out the entire bar.

One of the things to remember when using clay is that it can cause marring in the paint. I wanted to test how much marring is caused by Bilt Hamber Auto-clay. I clayed a panel on a black bonnet, first using only water as a lubricant, as Bilt Hamber suggest. I also used ONR diluted at the clay lubricant ratio to see if there was any advantage to using a clay lubricant with Bilt Hamber clays.

Contamination Removal (9.0/10)

In terms of contamination removal, I am drawing on my personal experience in order to score the clay. If I am using clay, I will first start with chemical decontamination. Using a tar and fallout remover will ensure as much contamination is removed prior to rubbing clay along the paint.

When using Bilt Hamber Auto clay, I use the ‘hashtag technique. I first use the clay in vertical motions and then horizontal motions, I do not use circular motions. I tend to work in fairly small sections, roughly 30 cm x 30 cm.

After using the clay, I am always amazed at how much contamination is removed from paint that otherwise looked quite clean. Paint always feels smoother after I have used Auto-clay, as does glass. Claying glass will improve the clarity and can help reduce wiper judder. I have also used Auto-clay to remove paint splatter from wet road markings, which it removed with ease.

Abrasiveness (7/10)

Regular Auto-clay is quite firm and is not the easiest to shape. It is more malleable in warmer temperatures, in the winter months I often hold the clay in my hand to warm it up or leave it to sit in war, water for a minute or two. With the clay warmed up, it is considerably easier to shape and form.

Form (9/10)

Auto-clay holds form very well, in colder temperatures a little too well. I like clay to be able to adapt to contour changes in the paint, which in colder weather it does not always do. On the plus side, the clay does not degrade during use, I have not seen any small bits of clay breaking off, which can happen with some lower quality clays.

Marring (7.5/10)

Marring is something is that is to be expected when using clay and is the reason it is essential to machine polish after using clay. While using Auto-clay, I have noticed that marring has been inflicted, but it has never been serious.

The photo below shows the marring that existed after using water alone.

The next photo shows the marring after using Auto-clay in conjunction with Optimum No-rinse Solution diluted to be used as a clay bar lubricant.

To me there was no noticeable difference in the two photographs, marring will occur regardless, emphasising the need to machine polish after claying. It is important to note that this marring will be removed easily by using a machine polisher. Another point to note is that the bonnet I tested the clay on was close to perfection, there were no swirl marks in the paint, so the only marks present have been caused by clay.


Bilt Hamber states that their clay only requires water as a lubricant and looking at the photos above, I cannot see any discernible difference. I have also tried using the clay using the soapy water from my rinse bucket, but again this did induce some marring. It is important to remember that there may be chemicals in certain shampoos that could break down the clay, for that reason I always recommend following the manufacturer’s recommendation with regards to lubrication.

Ease of Use (7.5)

The Bilt Hamber Auto clay does not come as part of a ‘kit’, as some other clay bars do from other manufacturers. As mentioned, it is quite a firm clay, tearing a piece off is quite difficult, which is why I opt to use a blade or scissors to divide the clay. The ability to use plain water as a lubricant is a big advantage for this clay and simplifies the process.

Value for Money (8.5/10)

Auto-clay Regular is sold in 200g blocks for a cost of just £9.95 ($12.10 USD), which is cheaper than most competitors to start with. I estimate I use about 50 g of clay on a car, which equates to roughly £2.50 ($3.04 USD) per car. Compared to other products used in detailing such as shampoo, wax or snow foam, this seems like a lot.

It is worth remembering that clay should absolutely not be used on a regular basis, it’s simply too abrasive for that. Regularly applying tar and fallout removers may completely remove the need to clay a car or reduce the time interval needed. I do not clay my car regularly, maybe once a year before an enhancement polish, so for me spending £2.50 ($3.04 USD) a year on clay represents good value.

About Bilt Hamber

Bilt Hamber is a UK-based manufacture of detailing products and industrial corrosion solutions. Some of their popular products include Surfex HD, Autofoam and Double Speed Wax.

They manufacture three grades of clay bar:

  • Regular, this is the most abrasive and is suitable for cars that have never been decontaminated or have a lot of contamination present, it is also the firmest of the clays
  • Medium, for cars that have moderate contamination, it is more suitable for winter use as it is more malleable
  • Soft, this is ideal for users who like to clay their cars regularly. This clay is the least abrasive and will induce less marring than the other grades

Bilt Hamber Auto Clay Regular FAQ

Does Bilt Hamber Auto-clay need a special lubricant?

Only water is needed to allow Auto-clay to glide along the paintwork surface. Testing showed that there was no noticeable difference in the marring caused between a dedicated clay lubricant and plain water.

When do I need to clay bar a car?

If your paint feels rough, it may be time to clay. Try using a tar remover or an iron fallout remover first, as this is a less aggressive method.

Which Bilt Hamber clay is best?

The three Bilt Hamber clays serve different purposes. Regular is intended for heavily contaminated cars. Medium is for cars with moderate contamination, while soft is for more regular usage. Medium and soft grades are easier to form into shape so are more suitable for use in wintertime.

Bilt Hamber clay seems very tough, is this normal?

Clay bars get firmer as they cool and softer as they heat up. If your clay bar feels too firm to use, first cut it into smaller chunks using scissors, then place the clay in warm water for 30 seconds. This will soften the clay and allow it to be formed into shape.

Final Thoughts

Bilt Hamber Auto Clay is an essential piece of kit to have as a detailing enthusiast or professional. Contamination will inhibit the durability of waxes and sealants, as well as detracting from the look of the car.

Auto-clay is a cost-effective and incredibly efficient way to remove this contamination. The regular grade would be most suited to professionals who regularly see neglected cars, or for a beginner of car detailing, as it is likely their car will have a built-up of contamination that will need to be removed. For those that regularly maintain their vehicles, the medium or soft bars would be more suitable.

One of the best features of Auto-clay is that water can be used as a lubricant, for me, it just simplifies the whole process and helps to lower the cost of detailing.

Grab it Now

Bilt Hamber Auto Clay Bar Regular 200g
  • Intense cleaning action for embedded contaminants
  • Only water needed as lubricant
  • Leaves an ultra clean, smooth finish

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