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Rotation Influences Stripe Removal performance

Can you guess if this stripe was removed by water, scarification (grinding) or rotary erasing? If so, email your response to for the answer

Can you guess if this stripe was removed by water, scarification (grinding) or rotary erasing? If so, email your response to

Lets dispel the myth and misinformation about grinders and blasters used in stripe removal.

  • The improper use of waterblasting causes surface damage
  • The improper use of “grinders” causes surface damage
  • The proper use of waterblasters damage some surfaces
  • The proper use of “grinders” will NOT damage surfaces

Stripe Removal Performance is Influenced by Rotation

Yes, stripe removal performance is influenced by rotation.

Stripe removal performance, from the standpoint of speed and surface scarring, is influenced by the cutting head’s directional rotation. The rotational direction of removal equipment (water, steel, carbide, diamonds, etc.), in either a vertical or horizontal direction affects pavement scarring.

Agency Confusion

There is confusion among DOT agencies as to how to best protect their pavement surfaces from improper removal methods. Some agencies believe that “grinders” cause surface damage and prevent its use on contracts. Agencies are outlawing the use of “grinders” in favor of waterblasting, even knowing that waterblasting is not the cure-all for stripe removal. This article dispels the myths about removal and helps the reader determine the best method when markings have to be permanently removed and not re-applied in the same location.

A “grinder” is a general term that is thrown out to represent every type of mechanical cutting device. What is not clear and misleading is that the term “grinder” is misused and misrepresented in striping. When everyone has access to the facts so they can make an informed judgment about what to allow or prohibit on striping contracts, everyone wins.

It’s time that the record is set straight about “grinders” so agencies can specify simply the clear results they expect and not the methods to achieve those results, so the job is completed properly. on time and on budget. 

What Agencies Expect When Contractors Remove Markings

  • The removed markings will not conflict with any new markings applied
  • Removed surface approximates the contiguous outlying surface profiles
  • The work is completed without deep pavement scars that allow water to accumulate or pond
  • The surface remains sound without fracturing, micro-cracking or undermining

What is a Grinder?

A grinder is not a grinder unless it’s actually a grinder. When removing pavement stripes, a scarifier, planer, eraser, groover, scabbler, or miller is NOT a grinder.

A grinder is actually a rotary-style machine outfitted with frictional force abrading stones or discs applied under pressure at right angles and moved across the surface until a nearly flat (SP 2) finish is achieved.

Turning of water, stones, metals or disc cutting devices over the surface in a drum-style (barrel) or rotary-style (planetary) should help identify if the equipment is a grinder or not.

Most surface-preparation and traffic-line removal work can be accomplished using either vertical drum-style scarifiers. These rotating cutters will create all the required profiles in the surface profile chart (SP1-SP10).

Vertical Drum-Style Eradicators

When agencies use the term “grinders,” they mostly are describing scarifiers, planers, millers, and groovers, the hardest-hitting impact equipment that leave sharp-edge marks.

These vertical cutting, trenching, and grooving eradicators, when engaged as stripe removers, quickly remove large volumes of materials with great cutting force. The hard force fractures both the marking material and surface into chips and dust producing a linear striation-grooving pattern when the equipment is directed in a straight path across and into the surface.

Scarifiers, outfitted with toothed cutters and spacers assembled on steel shafts mounted at the perimeter of a drum rotate at high speeds and flails to fracture or pulverize the surface producing vibration. The greater the vibration along with the cutting shear force concentrated narrowly through the cutting tip breaks up sound materials and causes weakening of unsound surfaces leaving potential surface micro-cracking or bruising.

The concentration of the cutters over a narrow area, such as the stripe alone, leaves a vertical cut impression of the cutter tip on the surface. The wider the spacing pattern, the deeper each cutter tip can reach, yielding deep surface scars.

If the removal process follows the original pavement marking pattern, removing the coating color but leaving a sharp-edge stripe pattern that can allow water to pool, a false stripe, called a ‘ghost line’ is created. This marking will reappear at night when surface is wet and headlight beams capture the false stripe.


A waterblaster can be outfitted on either a rotary disc or a drum style.

When waterblasters use vertical positioned pulsating jets on a drum, they demo hard or soft surfaces very fast, leaving voids and sharp edge grooves.

When these same jets are positioned away from vertical at a glancing angle on a spinning rotary disc, markings are removed from the surface, while the hard nonporous surfaces left intact. When these same jets remove very thick hard materials (thermoplastics) on soft surfaces (open graded surface coarse), water will undermine and rut the surface while washing away all the pavement fines and binder.

Rotary-Style Erasers

A rotary eraser is not actually a grinder. It is a combination impact and scraping planetary removal device.

Whereas vertical eradication concentrates the cutters over a narrow area, planetary rotary-style erasers spread the cutting force over a much wider area, leaving a non-grooved consistently smooth finish. The simultaneous vertical and horizontal, floating/planing, rolling-cutting-action pushes away the marking materials instead of driving the materials into the surface, like a scarifier or vertical-drum planer. The result is an “erased,” bevel-edged, feathered appearance without grooving or undulation patterns.

Depending upon the markings to be removed, the rotary eraser removal tool can be outfitted with select cutters each held on a spindle at a preset pitch and down pressure to control the angle and depth of cut. The eraser’s chassis includes cut-depth caster wheels that can be engaged by the operator to remove markings in a sweeping side-to-side action. This oscillating action peels and pushes the markings off the surface at a glancing angle to keep unstable surfaces sound with a smooth bevel-edged profile.

Dust-Free, Year-Round Removal

Any removal without water produces dust. A vacuum attached to any style eradicator (drum or rotary) will contain all airborne dust from the jobsite. To pickup any remaining materials, a secondary wand or a sweeper broom truck is used.

Since drum or rotary eradicators remove stripes without water, the surface remains dry for any immediate re-striping, thus shortening the work-zone closure. No water use means surface-prep and stripe removal can be a year-round operation.


For years misleading statements, half-truths or, quite simply, fiction, about “grinders” have been communicated among contractors and agencies. These myths have often been quoted uncritically or unchallenged, which has not helped to separate fact from fiction.

Every abrasive cutting action equipment from water, shot to frictional abrading equipment scar pavements. Unwanted scaring occurs when the removal action causes an unwanted pavement surface pattern such as a  conflicting guidance (ghost lines) or  an unstable pavement surface (fracturing, undermining, trenching).

Rotary erasers and waterblasters offer a similar removal appearance  because of the disc rotation. The eraser offers exact depth-of-cut control, and the waterblaster works best on hard, sound surfaces. Soft, exposed, or unsealed surfaces will be undermined and rut with prolonged water exposure.

Instead of calling all mechanical stripe eradicators “grinders,” define the equipment by its rotational style, – drum or rotary. Stripe removal is better defined by its rotation:  (1) drum-style vertical-cut rotation (scarifier, planer, millers or groovers); or (2) rotary-style (erasers, blasters or grinders) machines. For definitions, please click here.

Instead of prohibiting  the use of all “grinders” because of potential pavement scarring problems, lets give the contractors what is expected, a sound safe surface that matches the contiguous surface conditions without sharp-edge grooving.

By clearly defining the term “grinder” before outlawing its use removes the hardship so contractors can complete their job on time and on budget. Agencies should be specific as to what results they want to achieve.

Click here for specifications that focuses on the results, and not the recipe.

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