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Blackwood Management

Introducing the CLAY COURT GRINDER

Reconditioning of green and red clay tennis courts.

is now available in North America.
Introducing the CLAY COURT GRINDER.

Aggressively Scarify Clay Courts

The Best and Most Affordable Option for green HarTru and Red Clay Court Maintenance.

The CLAY COURT GRINDER alleviates the high cost of yearly clay court maintenance and
puts the monthly maintenance in the hands of your own staff. An investment up front pays for itself in the first year. The CLAY COURT GRINDER easily rolls over clay to

return it to a soft playing surface.

Weekly, Monthly or Total Clay Court Renovation

Weekly, Monthly or Total Clay Court Renovation
The first machine available to club owners and court maintenance companies for reconditioning of green and red clay tennis courts

can easily set depths for monthly refreshing of courts or deeper depths

for total court renovation.


North American Green Clay Courts...The results are clear.

Using the Clay Court Grinder on your green clay courts allows you to return your courts to their original softness. Go from hard crusty clay courts to soft clay courts in 30-40 minutes.

​Members will appreciate the outstanding transformation back to soft clay courts.

One pass with Clay Court Grinder


Olde World Design, Napa Valley, CA

Builder and maintenance of Har-Tru clay courts.

“The Clay Court Grinder helps us with one of the hardest jobs we have in this industry; breaking up a very hard, compacted, and crusted surface on any type of clay court. These courts can become impervious to water penetration. We bought the GRINDER for this specific reason. It’s like a mini rototiller that can pulverize a rock hard surface. The blades can be set to the exact depth needed for the court hardness. The surface is easily broken up and removed, replaced or recycled back into the court.”

Olde World Design builds and maintains clay court and bocce ball courts

Olde World Design


Olde world Design Video

Daniel Nestor Tennis Centre – Canada

6-court indoor year-round indoor clay facility

“We had been looking for a machine that would alleviate bringing in crews to renovate the courts each year at a high cost. We are a year-round indoor clay court facility and the courts get very hard after an indoor playing season. The Clay Court GRINDER allows us to do monthly maintenance ourselves allowing us to keep the courts soft year round. After running the GRINDER over the courts all we do then is add the HarTru binder for particular spots, along with bags of HarTru Coarse Blend, and we have a great playing surface. They’re like new courts again with minimal costs.”

Olde World Design builds and maintains clay court and bocce ball courts

Bethesda Country Club – Bethesda Maryland

Golf and Country Club with indoor/outdoor HarTru clay courts

​”Here at Bethesda Country Club in Bethesda, Md we have three clay courts with an above ground water system that we cover with an air supported structure each indoor season for 32 weeks. At the end of April each year, we take down our bubble and those three courts become outdoor clay courts.

These three courts have been “bubbled” now for thirty years. Each year when we take the bubble down we have struggled with eliminating “hot spots” on the courts where the clay is so baked and compacted that water cannot penetrate the surface. These “hot spots” are bothersome during the indoor season and actually dangerous for play during the outdoor season.

​We have gone through multiple processes to try and rectify the situation. In the spring of 2016, we purchased a “Clay Court Grinder”. Problem solved!!!

​We used the “Clay Court Grinder” after we took down the bubble in April. All hot spots were eliminated after three hours of using the grinder. The 3 clay courts immediately played up to a standard that our discerning members appreciated.

​I strongly recommend the “Clay Court Grinder” for any facility with indoor clay courts.

​Frank Hatten

Director of Tennis

Bethesda Country Club”


Up to 30mm (1.18 inches) and as little as 1mm (.04 inches)

The GRINDER is very suitable for indoor clay court renovation. When the courts harden because of indoor conditions this is when the product is most useful to control costs. (Please note safety and health precautions that should be taken when operating machinery in indoor space along with controlling dust from clay particles becoming airborne during renovation.)

The renovation using a CLAY COURT GRINDER can take about 4 hours if done properly. The results are immediate and play can take place without delay.

This is one of the greatest benefits of the GRINDER. It is small enough for individuals to use and is not difficult to run the machine. This saves on your maintenance budget and allows you to schedule maintenance on your time.

The blades are made from Hardox steel which is the same steel used in building heavy machinery like bulldozers. You can expect years of use with these blades. This lifespan will depend on how often you run the machine and how hard the clay is when renovations are done.

Occasional oil changes along with cleaning of the machine after use is important. The GRINDER is built with a dependable Honda engine… so is very reliable.

On HarTru clay courts we recommend tilting the machine up over the lines as you scarify. In some situations the machine can go over the court lines without damage but we recommend testing it on a section before proceeding.

Monthly use will keep the courts soft and in great condition. Set the depth to 3mm and run the machine over the entire court. Use a gator rake to rake over the surface to even out areas missed and then brush with a court brush. Add matieral when needed and water the court. You are ready for play with a totally renovated court within 3-4 hours.


Tips for Clay Court Maintenance

TIP #1 : Replacing Lines

TIP # 2: Reconditioning clay courts with the GRINDER

TIP #1 : Replacing Lines

Tearing up and replacing old lines can be time consuming and difficult without the right tools. Especially if the court is extremely hard and crusty.

To the right and below you can see the court line has been torn up and what remains are the holes from the nails and a great deal of damage to the court. 


STEP #1 : Clay Court Grinder

With one pass at a depth of 10mm the Clay Court Grinder begins to break up the hard clay pieces.

​With two passes you have a whole layer of finely graded material to work with. All the pieces of hard clay are pulverized and the nail holes have been filled in with the smaller particles of clay.

STEP #2 : Court Scarifyer or Gator Rake

Rake over the clay with a Gator Rake or Lute to smooth out the area. Depending on how deep you scarify with the Clay Court Grinder you will have excess mounds of clay that need smoothing.

Tennis court lutes are designed to both distribute new material on the court and break up and scrape away old material.

Small handheld Gator Rakes do an excellent job at redistributing material and agitating the court surface.

STEP #3 : Add HarTru Clay Binder

With green HarTru courts we recommend adding a bit of HarTru Binder clay over the area where the line will be replaced. This helps bind the material with fresh clay and also serves to fill in any additional holes.

Spread with a court brush to ensure surface is even to prepare for watering

STEP #4 : Water the clay

A very light watering will begin the binding process of the clay. Do not over water this area or you will get runoff of the clay.

The watered clay should look like this. As you can see the damage done to the court with removal of nails is totally gone and the surface is ready for new lines..

STEP #5 :Replace the lines and brush the court

Once the clay has dried you can now replace the lines. Once lines are installed, brush the court and check for bumps or nail heads that might cause tripping. Clean lines with a line sweeper and you are ready to play.

Estimated time to remove lines, scarify and replace lines per short line is 2 hours. 3-4 hours for longer side lines or the base line.

TIP #2 : Reconditioning clay courts with the GRINDER

It is recommeded to use the CLAY COURT GRINDER every month to avoid courts becoming too hard and crusty. It only takes 30-minutes to run the GRINDER over the court leaving the court smooth and ready for play.


Remove the net and gently wet the soil to keep clay dust particles from becoming airborne. We recommend wearing a breathing mask to alleviate breathing in dust during clay court installation or repairs.

For regular maintenance you can pass over the lines. Consider doing a criss cross over the entire court and lifting the Clay Court Grinder over the lines as you pass.

NOTE: Some lines will remain unaffected by the GRINDER but test on your court lines prior to committing to the entire court. You may need to lift the GRINDER slightly above the lines to

alleviate damage. The guide built into the Clay Court Grinder will allow you to scarify directly up to the line without damaging the line itself.


Adjust the Clay Court Grinder to a depth of 15-20mm and continue back and forth up and down the court until fully scarified. When depths are set deeper the machine will be hard to control due to the action of the steel blades. It will pull the operator. We recommend doing smaller depths and running over the court surface several times doing a little at a time. This allows for a more controlled operation of the unit.


If necessary remove some of the older material after the first run but if this is not always necessary depending on the age and quality of the material.


You will have a build-up of excess clay after using the GRINDER. Smooth the court out using a gator rake or Lute and then brush the court and clean the lines. A Gator rake will knock down any clay build-up left behind after using the GRINDER. We recommend adding bags of HarTru Coarse Blend to each side of the court. Use a Lute to spread this material for an even flat quality across the court.


Gently water the court again to ensure clay BINDER is working. The members will love the look of the court if you maintain them properly and monthly maintenance will alleviate bigger costs later..

The more frequent simple maintenance is done on clay courts with the Clay Court Grinder, the less necessary a more expensive maintenance project later. 



Annual budgets associated with clay court maintenance can be extremely high. The CLAY COURT GRINDER alleviates much of these yearly costs by keeping the court in prime condition throughout the year. If courts are properly maintained throughout the season, less expensive work is required annually.

The CLAY COURT GRINDER allows approximately 40% savings of material by regenerating the old crusted clay back to its softer form.

NOTE:  We always recommend adding new HarTur clay material during yearly maintenance on green courts. Your first pass on the court (3mm) with the CLAY COURT GRINDER produces clay material that should be removed and replaced with new  HarTru clay.

See our GRINDER Tips page for more information on court renovation and Clay Court GRINDER tips.

See breakdown and examples of cost savings that the Clay Court Grinder can achieve with regular maintenance and in-house court renovations


Monthly scarification of courts cost using CLAY COURT GRINDER

• Operate the CLAY COURT GRINDER at it’s lowest depth, 1mm (.04 inches)  It is not necessary to remove lines during this process.

• Groom court using Lute and the Court Brush

• Water and roll court.

TOTAL COST – STAFF LABOUR ONLY (3 hours approximately)  

The CLAY COURT GRINDER refreshes the clay surface and replenishes the packed down clay. Fresh clay can be added in as required.




The Daniel Nestor Tennis Centre (DNTC) is a 6 court indoor clay facility.     The HarTru courts were built in 2013. The court base includes 5 inches of Type A gravel and 3 inches of crusher dust and is entirely enclosed in a bubble year-round. These courts are not exposed to climate such as wind, rain or frost so loss of clay to wind or erosion is not a factor. All courts are watered by hand each morning so moisture is controlled.

The DNTC is open year-round with the most activity happening from   October through May of each year. The summer is filled with junior camps   so the shoulder seasons are May/June and September.

DNTC COURT MAINTENANCE REQUIREMENTS : Within two years the clay courts began to show their wear through hardening, a crusty surface, shallow areas, and depressions.  See the video on DNTC renovation and use of the CLAY COURT GRINDER by clicking on this link.

Costs estimates to have an outside source come in and fix these issues ranged from $18,000 to $25,000 USD. After discussions with several indoor clay facilities in North America facing the same problem, various remedies were suggested including using a cement scarifier. These are about 10 inches wide and have rotating blades (diamond tip) that work similar to the CLAY COURT GRINDER but with a much narrower grinding width compared to the GRINDER at 16 inches. Cost for rental was $300+ per day USD. This machine was unsuccessful since it left many ridges and lacked control of depth scarification required.

The decision to purchase the VENUS TERRAROSSA from Italy was made after reviewing the equipment and discussing with other facilities that had already purchased the machine. The CLAY COURT GRINDER is the North American version of the VENUS.


The following cost breakdown on the DNTC renovation of 6 courts is based on USD.

1) VENUS TERRAROSSA purchase                                 $5,900   

            (This is a one time cost)                              

2) HARTRU Binder Clay (6 bags per court x 6)              $2,520

3) HARTRU COARSE GRAIN (3 bags per court x 6)       $1,260

4) Labour                                                                           $1,800

TOTAL 2015 RENOVATION                                        $11,480 *

NOTE: Original quotes from suppliers were averaging between $16,000 and $25,000 for the work detailed above. A savings of at least $4000 in the first year.

*Shipping of HarTru clay material and VENUE MACHINE is not included in this cost. Labour was done by DNTC staff and small crew of part-time general labour help.

2016 DNTC Clay Court Maintenance BUDGET

In 2016 the DNTC did MONTHLY court maintenance to all 6 clay courts. No outside source or equipment was required because of the VENUS TERROSSA (CLAY COURT GRINDER) purchase in 2015. 

NOTE: This year court lines have been replaced so additional costs outside the scarification process are included for review.

1)  HARTRU Binder clay                                             $2,520

2) HARTRU COARSE GRAIN Topper clay                $1,680

3) Labour                                                                     $3,700

4) Tennis court line replacement                              $2,340

TOTAL 2016 RENOVATION                                 $10,240

Within two years the VENUS (CLAY COURT GRINDER) has paid

for itself.

For more information on CLAY COURT GRINDER shipping and costs please email courtgrinder@blackwodtennis.com or fill out the form on our CONTACT page of this website. We will respond within a day to your request


(480) 703-0522



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