How to Prepare Surfaces Before Re-Marking

Six months after we marked a warehouse floor in Moorabbin, the operations manager called. Their lines were peeling off in sheets. Entire sections lifting like stickers.

We inspected the site. The problem was immediately obvious. The concrete surface underneath the failed markings was black with oil contamination. Hydraulic fluid from forklifts, diesel from trucks, lubricants from equipment.

"Did you degrease this before marking?" we asked the previous contractor (they'd called us to fix the mess).

"We swept it," they said. "Looked clean enough."

That's not surface preparation. That's hoping for the best.

We stripped everything, degreased the entire floor with industrial alkaline cleaners, ground the contaminated surface layer off completely, allowed 48 hours drying time, moisture tested, then remarked properly.

Three years later, those markings are still perfect. But the client paid twice. Once for failed work. Once for proper work.

Surface preparation isn't the glamorous part of line marking. But it's the critical part. Skip it and your markings fail fast. Do it properly and they'll last 6-8 years in harsh industrial environments.

Here's what proper surface preparation actually involves.

Upload photos of your surface for preparation assessment and recommendations

Why Surface Preparation Determines Everything

Line marking materials (epoxy, thermoplastic, waterborne paint) bond to surfaces in two ways: mechanically and chemically.

Mechanical bonding: The material flows into surface texture and locks in physically.

Chemical bonding: The material reacts with the surface at a molecular level (primarily with epoxy on concrete).

Contamination blocks both bonding types. Oil, dirt, old paint, chemical residues. They create a barrier layer between your new marking and the surface. The marking bonds to the contamination, not the substrate. When the contamination fails, your marking fails.

According to Safe Work Australia workplace safety guidelines, inadequate floor marking that peels or degrades creates trip hazards and reduces visibility of safety zones. That means surface prep isn't just about making markings last longer. It's about workplace safety compliance.

The Numbers on Adhesion Failure

We've assessed roughly 80 failed line marking projects since 2009. Projects where markings peeled, delaminated, or failed prematurely. In 68 of those cases (85%), inadequate surface preparation was the primary cause.

Not material choice. Not application technique. Surface prep.

A distribution centre in Somerton had their warehouse floor marked by a budget contractor. Lines started peeling within 4 months. They called us to investigate.

We tested adhesion on the remaining markings. Pull-off strength was roughly 0.3 MPa. Industry standard is 1.5+ MPa for epoxy on properly prepared concrete. The markings were barely hanging on.

Cause? The contractor had painted straight over old failed markings, dirt, and oil contamination. No cleaning. No grinding. No preparation.

Cost to strip and remark properly: $18,500. The original marking cost: $8,200. They paid more than double to fix it.

Assessing Surface Condition Before Starting

Before any cleaning or preparation, assess what you're dealing with.

Surface Type Identification

Concrete: Most common for warehouses, carparks, commercial buildings. Accepts epoxy excellently. Requires mechanical profiling for optimal bonding.

Asphalt: Common for outdoor carparks and roads. Accepts thermoplastic well. Can accept epoxy with specialized primers.

Existing coatings: Painted or sealed surfaces need complete removal or aggressive profiling to expose fresh substrate.

Contamination Assessment

Walk the entire area looking for:

• Oil stains and patches (dark discolouration, slick feel)
• Chemical spills (unusual discolouration, texture changes)
• Grease buildup (common around equipment, loading docks)
• Dirt and dust accumulation
• Old paint or marking residues
• Rubber tire marks (difficult to remove, create bonding issues)

A warehouse in Campbellfield had roughly 40% of their floor contaminated with hydraulic oil. Impossible to see until we cleaned and wet the surface. The oil had penetrated 2-3mm into the concrete. We had to grind off the contaminated layer completely before marking.

Structural Issues

Check for:

• Major cracks (>10mm width) requiring repair
• Spalling or delamination
• Settlement or heaving
• Standing water indicating drainage problems
• Loose or friable surface material

These problems need addressing before marking. Line marking won't fix structural failures.

Pressure Washing and Deep Cleaning

First step: remove loose contamination.

Equipment Requirements

Minimum pressure: 3,000 PSI for effective cleaning Recommended pressure: 3,500-4,000 PSI for industrial floors Water temperature: Cold water adequate for most applications, hot water (60-80°C) for heavy grease

Flow rate matters too. Minimum 10 litres per minute for efficient coverage.

We use commercial trailer-mounted units with 4,000 PSI and 15 LPM flow. They clean warehouse floors much faster than small domestic units.

Pressure Washing Technique

Work systematically in overlapping passes. Hold the nozzle 300-450mm from the surface. Closer creates surface damage, further reduces cleaning effectiveness.

For carpark line marking projects, we typically pressure wash the entire surface even if it looks clean. Dust and fine contamination isn't always visible until you start cleaning.

Allow 24-48 hours drying after pressure washing before applying marking materials. Concrete holds moisture. Rushing this step causes adhesion failures.

When Pressure Washing Isn't Enough

Heavy oil contamination, thick grease, or chemical residues need chemical cleaning before or after pressure washing.

Dealing with Oil and Chemical Contamination

This is where most cheap contractors fail. They skip chemical cleaning to save time and money. Then markings fail.

Degreasing Methods

Alkaline degreasers: Most effective for oil, grease, hydraulic fluids. pH 12-14 products. Apply concentrated, allow 15-30 minutes dwell time, agitate with stiff brushes, pressure wash thoroughly.

Solvent cleaners: For specific chemical contaminations. Use with caution due to environmental and health concerns.

Steam cleaning: Effective for heavy grease. Requires specialized equipment.

We use commercial alkaline degreasers applied at manufacturer's recommended dilution rates. Cheap options from hardware stores don't work on heavy industrial contamination.

Application Process

1. Sweep or vacuum loose debris first
2. Pre-wet the surface with water
3. Apply degreaser at recommended concentration
4. Allow proper dwell time (don't rush this)
5. Agitate with stiff deck brushes or mechanical scrubbers
6. Pressure wash thoroughly with clean water
7. Check for remaining contamination (water beading indicates oil still present)
8. Repeat if necessary

A manufacturing facility in Keysborough had diesel contamination from truck parking. First degreasing pass removed roughly 60% of contamination. Second pass got another 30%. Third pass finally achieved clean surface. Total process took two full days.

They wanted to skip the third pass to save time. We refused. Either do it properly or find another contractor. They agreed to the third pass. Markings are still perfect 4+ years later.

Extreme Contamination

Sometimes contamination has penetrated too deep for chemical cleaning. Only solution: mechanical removal of the contaminated layer.

That Moorabbin warehouse mentioned earlier required grinding the top 2-3mm of concrete off completely. The contamination had soaked in during years of neglect. Degreasing wouldn't touch it.

Grinding cost: roughly $4,800 for 3,000m². But the alternative was marking over contamination that would guarantee failure.

Send us surface photos for contamination assessment and preparation recommendations

Removing Old Line Markings

Old markings must be removed completely. Don't paint over them.

Why Complete Removal Matters

Old markings create an uneven surface. New markings follow the profile of old markings, creating visible ridges and shadows. Looks unprofessional.

More critically, if old markings are failing (peeling, cracking, delaminating), new markings will fail at the same locations. You're bonding to a failing substrate.

Removal Methods

Diamond grinding: Most effective for thermoplastic and thick epoxy. Specialized equipment with diamond segments removes markings and profiles the surface simultaneously. Expensive but thorough.

Shot blasting: Effective for paint and thin coatings. Creates excellent surface profile. Generates significant dust requiring proper containment.

Water blasting: Ultra-high-pressure water (10,000+ PSI) removes markings without damaging concrete. Expensive equipment, specialized operators required.

Chemical stripping: Rarely effective for industrial markings. Works on fresh paint, struggles with cured epoxy or thermoplastic.

We primarily use diamond grinding for thermoplastic removal and shot blasting for old paint removal. Both methods profile the surface while removing old markings, achieving two objectives simultaneously.

Partial Removal vs Complete Removal

Some contractors argue you can "spot remove" damaged areas and paint over the rest. We disagree. Inconsistent surface preparation creates inconsistent adhesion and lifespan.

Either remove everything or commit to remarking over perfectly intact existing markings (rare situation).

Creating the Right Surface Profile (CSP)

Clean isn't enough. The surface needs texture for mechanical bonding.

Concrete Surface Profile (CSP) Standards

The International Concrete Repair Institute defines CSP levels from 1 (lightest) to 10 (most aggressive).

CSP-1: Very light texture, looks almost smooth. Achieved by light sanding. Insufficient for most line marking.

CSP-2: Light sandpaper texture. Ideal for epoxy line marking. Achieved by light shot blasting, acid etching, or light grinding.

CSP-3: Medium sandpaper texture. Acceptable for epoxy, good for heavy-duty coatings. Achieved by moderate shot blasting or grinding.

CSP-4+: Aggressive texture. Usually excessive for line marking, more appropriate for thick coating systems.

We target CSP-2 for all warehouse and carpark epoxy applications. It provides optimal bonding without excessive surface roughness.

Achieving CSP-2 Profile

Method 1: Shot blasting Portable shot blast equipment propels steel shot at the surface. The impact creates consistent profile across large areas. Generates significant dust requiring containment and filtration.

Coverage rate: 150-300m² per hour depending on equipment size and required profile depth.

Method 2: Diamond grinding Diamond-impregnated segments remove a thin surface layer while creating profile. Less dust than shot blasting. Works well on contaminated surfaces requiring removal of the contaminated layer.

Coverage rate: 100-200m² per hour depending on equipment and surface hardness.

Method 3: Acid etching Diluted hydrochloric or phosphoric acid chemically etches concrete. Environmental concerns limit use. Not effective on heavily contaminated surfaces. We rarely use this method anymore.

Checking Profile

Visual inspection and feel give rough indication. For critical projects, use CSP comparison chips (physical samples showing each profile level) to verify.

Alternatively, use a surface profile gauge (measures peak-to-valley depth in microns).

Moisture Testing and Drying Time

Moisture trapped under line marking causes adhesion failure. This is especially critical for epoxy, which won't bond to wet surfaces.

Acceptable Moisture Levels

Epoxy applications: Maximum 6% moisture content Thermoplastic applications: Maximum 8% moisture content Waterborne paint: Less critical but still better on dry surfaces

Moisture Testing Methods

Method 1: Calcium chloride test Place anhydrous calcium chloride under a sealed plastic dome for 72 hours. Weigh before and after. Calculate moisture vapor emission rate (MVER). Standard method for coating applications.

Method 2: Electronic moisture meter Pin-type or pinless meters measure electrical resistance or capacitance to estimate moisture. Faster than calcium chloride but less accurate. Good for quick screening.

Method 3: Plastic sheet test Tape plastic sheet to concrete. Check after 24 hours for condensation on underside. Crude test, not quantitative, but indicates obvious moisture issues.

We use electronic meters for initial assessment and calcium chloride tests for verification before large projects.

Managing Moisture Issues

Allow proper drying time: After pressure washing, concrete needs 24-48 hours minimum in warm, dry conditions. Longer in cold or humid weather.

Mechanical drying: Use fans or dehumidifiers to accelerate drying in enclosed spaces.

Moisture barriers: In extreme cases, apply moisture barrier primers before marking. Adds cost and time but prevents failures.

A basement carpark in Docklands had persistent moisture issues from groundwater. Standard drying time wasn't sufficient. We applied moisture-barrier epoxy primer before marking. Added roughly $3,200 to the project cost but prevented guaranteed adhesion failure.

Three years later, markings are perfect. Without the barrier, they would've failed within 6-12 months.

Crack Repair and Surface Repairs

Major cracks or damaged areas need repair before marking.

When Repairs Are Necessary

Active cracks (still moving): Require structural assessment and proper repair. Don't mark over them until stabilized.

Stable cracks >5mm width: Fill with flexible polyurethane or epoxy crack filler.

Spalled areas: Remove loose material, clean thoroughly, patch with repair mortar.

Surface delamination: Remove failed material completely, clean, patch.

Small hairline cracks (<2mm) can usually be marked over without repair. The line marking spans the crack adequately.

Repair Process

1. Clean crack or damaged area thoroughly (compressed air, wire brushing, vacuuming)
2. Ensure completely dry
3. Apply primer if required by filler manufacturer
4. Fill crack or patch area with appropriate repair material
5. Allow full cure time (24-72 hours typical)
6. Grind or sand repair flush with surrounding surface
7. Proceed with line marking

Repairs add time and cost but they're necessary. Marking over structural damage doesn't fix the damage. It just hides it temporarily.

Different Requirements for Different Materials

Surface prep varies slightly depending on which line marking material you're applying.

Epoxy Line Marking Preparation

Most critical preparation required. Epoxy relies on both mechanical and chemical bonding. Contamination blocks chemical bonding completely.

Requirements:

• Thorough degreasing of any contamination
• CSP-2 minimum surface profile
• Maximum 6% moisture content
• Complete removal of old coatings
• Temperature between 10-30°C during application

Thermoplastic Line Marking Preparation

Less sensitive to contamination because bonding is primarily mechanical and thermal. Hot thermoplastic can penetrate light contamination.

Requirements:

• Pressure washing to remove loose debris
• Degreasing heavy oil contamination (light contamination less critical)
• Maximum 8% moisture content
• Old markings can sometimes be marked over if sound
• Surface profile less critical (thermoplastic creates its own mechanical bond through heat)

Waterborne Paint Preparation

Least demanding but still requires proper preparation for reasonable lifespan.

Requirements:

• Clean, dry surface
• Remove loose material and dirt
• Degreasing heavy contamination
• Light surface profile beneficial but not critical
• Can be applied over existing paint if sound and well-adhered

Equipment and Materials Needed

Proper surface preparation requires specific equipment. Don't attempt it with household tools.

Minimum Equipment List

Pressure washer: 3,000+ PSI, 10+ LPM Degreaser: Commercial alkaline product, 20L minimum Stiff deck brushes: For agitating degreaser Diamond grinder or shot blaster: For creating surface profile (rental options available) Moisture meter: Electronic pin-type minimum Safety equipment: Eye protection, hearing protection, respirator (grinding generates silica dust)

For Large Projects

Ride-on scrubber: Mechanized cleaning for areas >1,000m² Industrial dehumidifier: For moisture management in enclosed spaces Surface profile gauge: For verification of profile depth Crack routing equipment: For preparing cracks >5mm for filling

Rental vs Purchase

Small contractors doing occasional line marking projects should rent specialized equipment (grinders, shot blasters). Purchase only makes sense above 10-15 projects annually.

We own all equipment because we complete 200+ projects yearly. But we started with rentals in 2009 until project volume justified purchasing.

Timeline Considerations

Proper surface preparation takes time. Rush it and markings fail.

Typical Timeline for 1,000m² Warehouse

Day 1 morning: Initial assessment, contamination identification Day 1 afternoon: Pressure washing entire area Day 2: Degreasing contaminated areas (might require two passes) Day 3 morning: Grinding or shot blasting for surface profile Day 3 afternoon: Final cleaning, moisture testing Day 4: Drying time (weather dependent, might need 48 hours) Day 5: Line marking application

Total: 4-5 days minimum before marking begins.

Contractors who promise "clean and mark in one day" are skipping critical steps. You'll repaint sooner.

Weather Impact

Hot, dry weather accelerates drying. Cold, humid weather extends drying times significantly.

A winter project in Ballarat required 72 hours drying time after pressure washing. Summer projects dry in 24-36 hours.

Indoor climate-controlled spaces dry faster and more predictably than outdoor areas.

Upload your site plans for timeline estimates and preparation scheduling

What Happens When Surface Prep Is Skipped

We've repaired enough failed projects to know exactly what happens when contractors cut corners.

Adhesion Failure Timeline

Poor cleaning, no degreasing:

• Markings look fine initially
• Within 2-6 months, edges start lifting
• By 6-12 months, sheets of marking peel off
• Complete failure by 12-18 months

No surface profiling:

• Markings appear okay initially
• Gradual degradation from traffic wear
• Failure starts in high-traffic areas within 12-18 months
• Complete failure by 24-30 months

Marked over wet surface:

• Initial appearance normal
• Within weeks, small bubbles appear under markings
• Bubbles grow and merge
• Large sections delaminate within 3-6 months

The Financial Cost

That Moorabbin warehouse from the beginning paid roughly $9,500 for failed markings. Then paid us $18,500 to strip and remark properly. Total cost: $28,000.

If they'd hired us initially for $21,000 (proper preparation included), they'd have saved $7,000 and 6 months of degraded safety marking.

Skipping surface prep saves 20-30% on the initial project cost. Then costs 150-250% when you're forced to remark within 18 months.

The Safety Cost

Failed markings create safety hazards. Faded or missing pedestrian walkway markings increase forklift-pedestrian incident risk. Unclear bay boundaries in carparks cause vehicle damage and disputes.

According to Safe Work Australia, inadequate floor marking contributes to workplace incidents. That's not just an operational issue. It's a legal compliance issue.

What We've Learned From 5,000+ Projects

We've prepared surfaces in freezing Tasmanian warehouses and steaming Queensland logistics centres. Basement carparks with moisture issues and outdoor facilities in full desert sun.

Surface Prep Is Never Optional

The projects that last 8+ years all had meticulous surface preparation. The projects that failed early all cut corners somewhere in the prep process.

There's no secret to long-lasting line marking. It's boring, methodical surface preparation.

Test Don't Guess

We moisture-test every project. We verify degreasing effectiveness before proceeding. We check surface profile visually and tactilely.

Testing takes 30 minutes. Redoing failed work takes days and costs thousands.

Client Education Matters

Facility managers often don't understand why preparation costs so much. "Why can't you just paint over the old lines?"

We explain. Show photos of failed projects. Explain adhesion principles. Most clients appreciate the education and approve proper preparation.

The ones who insist on shortcuts? We politely decline those projects. We won't put our name on work we know will fail.

Weather Windows Are Real

You can't rush drying time. Schedule projects during favorable weather windows. Don't promise completion dates that require skipping drying time.

We've delayed projects by 2-3 days waiting for proper drying conditions. Short-term schedule pain beats long-term adhesion failure every time.

Get Professional Surface Preparation

Surface preparation requires specialized knowledge, proper equipment, and rigorous attention to detail. It's not a job for general maintenance staff or cheap contractors using household equipment.

We've completed 5,000+ line marking projects across Australia since 2009. Every one started with proper surface preparation. That's why we've never had a council issue an improvement notice for failed markings and why our projects routinely last 6-8 years in harsh industrial environments.

What we provide:

• Complete surface assessment with contamination identification
• Comprehensive preparation specification based on actual conditions
• All necessary equipment (pressure washers, grinders, shot blasters)
• Chemical cleaning with commercial-grade degreasers
• Moisture testing and verification
• Surface profile verification
• Timeline planning accounting for weather and drying
• Full documentation of preparation work completed

Contact Director Niel Bennet: 0417 460 236

Your line marking is only as good as the surface underneath it. Let's prepare it properly.