Paint and Coatings Knowledge

Chemistry, ingredients and coating technologies

Describe independent dimensions

Identify binder chemistry, carrier, cure mechanism, component count, pigment/finish, application process and service. Waterborne describes delivery, not resin identity or safety. Acrylic can describe thermoplastic, self-crosslinking or reactive polyol systems; 1K is not always physically drying. BASF illustrates these forms S04. Never derive a commercial recipe from a label.

Use a mechanism map: physical carrier loss/particle consolidation; oxidative cure in suitable oils/alkyds; reactive complementary groups such as epoxy/amine or polyol/polyisocyanate; and appropriate heat, moisture or radiation triggers. Check hybrids and exceptions.

Ingredients and film structure

Binders form the matrix; pigments provide colour, opacity or function; extenders affect packing and properties. Distinguish volatile carriers and reactive diluents. Additives affect wetting, dispersion, foam, flow, rheology, preservation or film formation. Do not prescribe additives for an unknown finished paint.

BYK separates pigment processing into wetting, mechanical deagglomeration and stabilisation S05. A dispersant cannot replace adequate mechanical processing. Investigate settling, flocculation, flooding/floating, viscosity and colour-strength changes together.

PVC uses pigment/extender volume divided by pigment/extender plus binder-solids volume. CPVC concerns sufficient binder to fill the pigment structure; physical/optical properties can change markedly around it S06. Do not use weight percentages or equate more pigment with better hiding. Dispersion, optics, thickness and substrate contrast matter.

Drying and curing

The waterborne-film review describes evaporation, particle packing/deformation and polymer interdiffusion S01. Temperature, coalescents and application conditions affect continuity. Touch dry does not establish full resistance. Tg and minimum film-forming temperature are related but different measurements. Physical drying can coexist with chemical crosslinking, as Covestro's waterborne 2K PU diagram illustrates S02.

BASF's film-forming additives illustrate changes to film formation, flexibility and adhesion S03. Explain the mechanism without prescribing an unsupported additive dose.

Technology selection

Compare appearance/UV retention, corrosion barrier, chemical and abrasion resistance, flexibility, heat, application and maintenance. Avoid absolute rankings such as 'epoxy is always best', 'waterborne is weak' or '2K means polyurethane'. Primer and topcoat functions differ. Generic tendencies shortlist options; exact formulated-system evidence establishes suitability.

QD/quick-dry describes a product characteristic. Confirm binder, solvent, substrate/exposure and overcoating information. Names across manufacturers or sectors do not establish equivalence. As research examples, Star Paint's QD Spraying Enamel page identifies a styrenated alkyd S42, whereas Atlas Paints' YEKAShield WB QD page identifies a waterborne acrylic copolymer S43. These pages illustrate different chemistries under QD naming; they do not establish cross-brand equivalence, current TDS instructions or store availability.

Formulation reasoning

Use declared raw-material data on the correct as-supplied/solids basis. Evonik explains EEW, AHEW and the theoretical epoxy-amine calculation: curing-agent parts per hundred resin = 100 × AHEW / EEW S07. Calculate blends by equivalent balance rather than arithmetic averaging of equivalent weights. Finished kits can contain pigments, solutions, diluents and supplier-selected stoichiometry: never infer a kit hardener dose from this generic formula.

Frame formulation work as hypotheses and laboratory tests for dispersion, rheology, application, film formation/cure, adhesion, resistance and storage stability. Do not claim a usable formulation, equivalent product or certified performance without validation.

Selecting systems for different surfaces

Build a performance brief

Establish what must be protected, from what, for how long before maintenance, and under which application constraints. Record appearance, wear, UV/weather, chemical identity/concentration/temperature, immersion versus splashing, cleaning, movement, downtime and access. A practical system is substrate preparation + primer/tie coat + intermediate/body coat + finish + detailing + cure/maintenance. Do not prescribe a default number of coats or 'universal primer'.

Assess these conditions before naming products:

AMPP treats visible cleanliness, invisible soluble contamination and surface profile as separate preparation concerns S40. A clean-looking surface is not automatically ready.

Compare systems, not labels

Explain two or three plausible system approaches with advantages, limitations and evidence still needed. Distinguish inhibitive pigments, zinc-rich galvanic primers and barrier finishes. A zinc-phosphate primer is not automatically a zinc-rich galvanic coating; Dulux's steel note illustrates these mechanisms S41.

For galvanised surfaces, use preparation suited to the zinc condition and selected coating. Dulux discusses controlled sweep blasting and alternative approaches S13. Do not remove protective zinc indiscriminately or assume every alkyd/etch primer is approved. Confirm actual product guidance and consider a representative adhesion trial.

For concrete, do not equate dry-to-touch with acceptable internal moisture. For old paint, assess the weakest existing layer and hazardous-coating risks before abrasive work. A solvent spot test is limited evidence, not full chemical identification.

For plastics, identify the polymer and manufacturer process. Do not recommend flame treatment or aggressive solvents as a generic DIY procedure. For wood and building fabric, follow the dedicated module.

Decide and communicate

State the selected approach, alternatives, decisive conditions and what must be confirmed. Separate technical suitability from local availability, cost or a store's catalogue. Escalate severe-service specifications, structural defects, uncertain hazardous substrates and special approvals to qualified specialists.

Automotive refinishing

Assess the repair

Identify substrate and repair layers: steel/aluminium/plastic/composite; original versus previous repair; corrosion, filler, primer/surfacer/sealer; colour type; clearcoat and target finish. Distinguish cosmetic repair from OEM structural/corrosion repair procedures. Follow the vehicle manufacturer's repair constraints where relevant.

Plan from sound substrate to finish. Identify contamination before sanding; assess old coatings; use the specified preparation and compatible repair system. Do not assume an etch primer, epoxy, polyester filler and 2K surfacer can be interchanged or overcoated in every order. Check documented interfaces and cure windows.

PPG's restoration guide covers preparation, equipment selection and colour/repair processes S08. Use it for workflow principles; its regional product codes, abrasive details and pressure settings are not universal instructions for another system.

Read the whole recipe

Verify coating, hardener grade, reducer, additives, ratio by mass/volume, percentage basis, induction if specified, pot life, viscosity method, nozzle/pressure, coats, flash-off, bake/cure and recoat limits. Distinguish basecoat/reducer from clearcoat/hardener requirements. A hardener guide naming a coating is not automatically that coating's complete application recipe.

Select grade from documented temperature/repair conditions. Do not invent boundary choices when a chart says below/above a temperature but omits equality. Do not infer a thinner percentage applies to base only or activated mixture. Ask or retrieve the missing basis before calculating.

PPG's hot-weather waterborne advice requires its specified reducers S09. Explain that evaporation, atomisation and metallic orientation interact; do not fix an unsuitable gun setup by adding arbitrary thinner.

Control colour and finish

Check code and variant, existing weathering/repairs, lighting and substrate shade. Use a representative sprayout at the intended application conditions. Metallic/pearl orientation and coat sequence can affect appearance independently of the colour formula. See Colour, gloss and appearance. Matte finishes need their own product-specific process; do not assume polishing a matte repair is acceptable.

Control application and acceptance

Confirm booth, airflow, compressed-air cleanliness, equipment compatibility and safe spray controls. Set pressure at the location specified by the gun maker; air-cap pressure, inlet pressure and pump pressure are different quantities. Trial the spray pattern using the intended system.

Track flash-off, intercoat windows, film build, substrate temperature and actual bake conditions. Separate dust-free, handling, polishing and full service cure. Correct defects only within the system's documented repair procedure and sufficient remaining film.

See Paint defects and failure diagnosis for cratering, solvent pop, mapping or poor adhesion. See Safety, handling and environment before spraying isocyanate-containing products. Do not promote 'waterborne' or a 2K aerosol as a harmless alternative.

Buildings, wood, roofs and waterproofing

Walls and decorative work

Distinguish new plaster/masonry, gypsum, previous paint and trim. Establish exposure, cleaning/abrasion, moisture source, alkalinity, cracks, chalking and existing adhesion before selecting primer and finish. Nippon's Singapore guidance explains why chalky weak material undermines new paint S15. Removing/rectifying the failure mechanism comes before coating over it.

Ask what a moisture reading measures, which instrument/method was used and the relevant product threshold. Do not universalise a percentage or a fixed plaster-curing time. Room humidity, substrate moisture and internal slab RH describe different things.

Distinguish moisture intrusion, rising damp, condensation and plumbing leaks. A stain-blocking or alkali-resistant primer is not automatically a waterproofing system. Salts and recurrent damp need diagnosis of the cause. Cracks may be static defects, construction joints or movement requiring different detailing.

Wood

USDA's 2021 finishing chapter relates performance to species/anatomy, extractives, moisture, weathering and finish type S14. End grain can absorb differently; extractives can discolour coatings; wood movement stresses films. Establish timber condition, previous finish, exposure and maintenance expectations.

Compare penetrating finishes, opaque film systems and clear varnishes by appearance, protection and maintenance. Clear outdoor finishes do not automatically preserve an unchanged colour or achieve the longevity of a pigmented system. Confirm exterior suitability, UV performance, water exposure, preparation and refinishing process. Interior furniture hardness is a different requirement from exterior dimensional movement.

Avoid improvised wood-preservative recipes or guaranteed life. Match the complete stain/sealer/topcoat system and verify the substrate's coatings/preservative history.

Roofs and waterproofing

First identify roof material, slope/drainage, standing-water duration, joints, penetrations, movement, traffic, condensation and existing membranes. Distinguish a decorative roof paint, reflective coating and a complete waterproofing membrane.

Sika's South African Sikalastic-560 PDS (September 2025, v06.01) distinguishes a reinforced roof system and limitations, including long-term ponding, rising moisture and permanent immersion S19. This product example does not establish limits for all roof membranes.

Check substrate compatibility, primers, reinforcement/detailing, consumption/thickness, weather window, rain resistance, cure and traffic protection. Colour/reflection claims do not prove thermal-insulation performance. A larger generic coverage estimate must not reduce the required membrane thickness. Escalate structural movement, asbestos-containing roofing, failed drainage or inaccessible details for competent inspection.

Protective and marine coatings

Define exposure before specifying

Separate atmospheric corrosion, splash/tidal exposure, immersion and buried service. Identify substrate, salinity/pollution, condensation, chemicals, operating temperatures, abrasion, cathodic protection and maintenance access. Local microclimate can matter more than the broad geographic label.

Hempel's corrosion-selection guide links environment, substrate, durability and preparation to system selection S21. ISO 12944-1's public catalogue describes the series scope S32. Do not declare a structure C5 merely because it is coastal, equate a durability class with a warranty, or treat an atmospheric scheme as qualified for immersion.

Use zinc-rich/inhibitive/barrier roles as alternatives requiring system evidence. Confirm zinc-primer preparation and overcoating, stripe coats/edges, intermediate build and finish function. Recognise that generic resin descriptions alone cannot establish chemical resistance, service temperature or compatibility. Request chemical identity, concentration, contact time, temperature, cleaning and combination of stresses.

Inspection and specification

Document substrate assessment, preparation grade/profile, soluble contamination, environment, product/component identity, coat sequence/thickness, recoat windows, cure, repair and acceptance. See Application and quality inspection. Never invent the maximum salt level, profile, DFT or holiday-test voltage from a generic coating family.

Ask for current manufacturer specifications and qualified review for chemical tanks, CUI, high heat, offshore severe service, buried pipelines or fire protection. A salt-spray-hour result does not provide a direct conversion to field years. ISO 9227's public abstract describes a test method, not a universal service-life model S34.

Marine

Distinguish topsides, underwater hull, ballast, cargo spaces and potable-water tanks. An antifouling coating controls biological attachment; it is not interchangeable with a general corrosion coating. Consider vessel material, speed/use, idle periods, water conditions, docking, old coating compatibility and application/cure-before-immersion conditions.

The IMO AFS page describes international controls on harmful antifouling systems, including organotin and cybutryne S23. Confirm vessel scope, jurisdiction, dates and current applicable controls before making a compliance conclusion. Do not imply every boat worldwide has identical certification duties.

Contain hazardous residues when discussing removal and maintenance; avoid directing discharge to water. Verify antifouling substrate compatibility and the complete tie-coat/system with the manufacturer. For potable water or food-contact claims, consult the exact certification rather than inferring suitability from 'marine' or 'epoxy'.

Floors, road marking, powder and specialist uses

Resin flooring

Define loading, traffic, abrasion, slip requirements, cleaning chemicals/temperature, hygiene, UV, downtime, moisture and movement. Distinguish thin coatings, self-smoothing layers, broadcast systems and thicker mortar/screed constructions. Adding aggregate changes yield and texture; a generic litres-per-square-metre estimate cannot substitute for the system's consumption.

Check concrete strength, laitance, curing compounds, contamination, substrate profile, cracks/joints and the specified moisture-test method. ASTM F2170 measures in-situ slab RH S31; its results cannot be read as mass-percent moisture. A surface meter reading is not automatically interchangeable.

Reviewed product example: the South African Sikafloor-263 SL ZA PDS, June 2022 v02.01, states 79:21 A:B by weight, with conditions and temperature-dependent pot life S18. Use this as an interpretation example only; retrieve current local documents before a job. Do not apply 79:21 by volume, assume this floor system covers rising moisture, or remove the importance of substrate-temperature/dew-point limits. Parts, filler and mixed density require correct identities and bases.

Check blush/recoat preparation with the exact system. WEST SYSTEM's own epoxy guidance specifies water washing for its amine blush before relevant sanding/overcoating S20. Do not make a solvent wipe the universal blush remedy.

Road marking

Separate waterborne/solventborne traffic paints, thermoplastic, reactive systems and preformed materials. Define pavement type/age, traffic, climate, colour, skid resistance, application equipment and reopening requirements.

FHWA's 2022 guidance explains retroreflective elements partially embedded in different binders S24. Dry and wet-night performance differ; visible white colour is not evidence of adequate night visibility. Retrieve the road authority's current specification for material, thickness, bead characteristics/application, friction and acceptance. Do not transfer US requirements into South Africa automatically.

Powder and radiation cure

Distinguish thermoplastic fusion from thermoset reaction; identify resin/crosslinker, pretreatment, substrate heat tolerance and target performance. Allnex's historical resin guide includes polyester/hybrid and UV powder technologies S25. It is a chemistry discovery reference, not current product selection.

Axalta's AE80013301620 TDS labels its cure chart by object temperature S26. Oven setpoint is not the same as part temperature. Verify current product schedule and actual part-temperature history, including section thickness and thermal lag. Do not generalise a temperature/time chart to every powder. Check powder compatibility, reclaim, contamination and application/equipment safety.

Special approvals

Food-factory flooring does not establish direct food-contact or drinking-water suitability. NSF/ANSI/CAN 61 concerns health effects of materials contacting drinking water S38; verify the exact listed product, use conditions and local acceptance. Also verify exact certified assemblies for fire protection. Refer intumescent thickness design, aerospace, nuclear and other critical-service approvals to the applicable qualified specialist.

Application and quality inspection

Control a complete process

Build a job-specific inspection plan rather than supplying a universal checklist. Use accepted project requirements and current manufacturer documents for preparation, profile, contamination, climatic limits, mixing, thickness, recoat/cure and acceptance.

Before coating, record substrate and old-coating condition, cleaning/preparation method and evidence, dust/salts where relevant, environmental/substrate measurements and instrument identification. AMPP's surface-preparation scope distinguishes cleanliness, salts and profile S40. Visual blasting grade is not a complete contamination assessment, and different preparation methods need not create identical profiles.

During application, check product/component batch identity, storage/shelf conditions, temperature, stated ratio/basis, mixing/induction, clock start/pot life, approved thinner, equipment settings, wet build and intercoat windows. Do not reset expired pot life by adding solvent. Track environmental changes rather than relying on a single morning reading.

Check the reference point for spray pressure and the viscosity cup and temperature. Ford/DIN/ISO cup seconds are not automatically interchangeable. Sprayer pump pressure and gun inlet/air-cap pressure are not the same measurement. Follow gun, coating and equipment instructions.

Film thickness and consumption

Distinguish wet-film measurement from dry-film inspection, and per-coat thickness from complete system thickness. Jotun's application guidance discusses WFT/DFT control and practical coating losses S22; See Coverage, film thickness and mixing calculations for volume-conservation arithmetic. Thinner can alter the wet thickness needed for the same dry build. Overspray, profile, porosity and uneven application affect practical consumption.

ISO 19840's public scope concerns DFT on rough surfaces, instrument adjustment, sampling and acceptance; it excludes nominal DFT below 40 micrometres S33. Obtain the applicable full standard and project specification before claiming a conforming inspection or inventing sampling counts/tolerances. Check instrument substrate suitability and geometry. A single reading does not characterise an entire structure.

Adhesion and performance tests

These points come from public issuer scope/significance pages S29, S30, S31, S34, not purchased full methods. For concrete pull-off, retrieve the concrete-specific method rather than automatically applying the metal procedure. A glue failure may limit the conclusion about coating/substrate bond strength.

Choose tests that address the mechanism and specification. Do not invent acceptance thresholds for soluble salts, holidays, abrasion, cure or adhesion. Keep records of results, locations, conditions, instrument checks, deviations and repairs. Final acceptance and warranty belong to the competent authorised parties.

Paint defects and failure diagnosis

Investigate before prescribing

Separate observation, history and hypothesis. Ask when the defect appeared, its distribution and affected layers; preparation; exact materials/batches; ratio/thinner; film build; flash/recoat/bake; temperature/RH; equipment/air quality and subsequent exposure. Photos can help describe a defect but rarely establish a sole root cause.

Rank likely mechanisms and specify evidence that would change the ranking. Preserve samples and batch/job records if a consequential dispute exists. Avoid destructive testing or removal until old-coating hazards and inspection needs are assessed.

The PPG defect index is a diagnostic discovery tool S12, not proof that every similar-looking defect has the same cause.

Worked mechanisms

PPG's cissing guidance identifies silicone as one possible cause alongside grease/wax, air-equipment contamination and incompatible materials S10. Do not diagnose every crater as silicone or immediately prescribe an anti-cissing additive. Inspect cleaning sequence, environment and compressed-air maintenance; obtain manufacturer approval for additives.

PPG's solvent-pop guidance links trapped solvent, excessive build and inappropriate cure/reducer conditions S11. A 'faster drying' thinner or hotter bake can worsen the problem. Verify the product instructions and actual film/cure history before recommending corrective refinishing.

For epoxy surface blush, identify the system and conditions and follow its cleaning/recoat procedure S20. Do not confuse surface residue with uncured bulk resin. A soft coating can involve ratio, mixing, temperature, incompatible components or incomplete cure; more hardener is not a universal repair.

For wall peeling/chalking, inspect moisture and the strength of the underlying material S15. Painting over a weak layer does not fix that layer.

Repair and prevention

Choose the least destructive technically supported repair, subject to product instructions and sufficient remaining film. Distinguish polishing defects from failures needing removal or substrate repair. Define a small representative trial where appropriate, acceptance checks and prevention measures linked to the suspected cause. Escalate severe corrosion, persistent moisture, structural movement, hazardous old coatings or disputed high-value failures to competent inspection.

Colour, gloss and appearance

Separate several effects

Colour formulation, substrate/groundcoat, opacity, film thickness, surface texture, gloss, illumination, viewing geometry and human adaptation can all influence the apparent match. A code, screen image or single instrument number does not guarantee a physical match.

Distinguish hue, lightness and chroma. For metallic/pearlescent finishes, viewing/application geometry and flake orientation add complexity; use the appropriate multi-angle process and representative sprayout. Do not promise an exact formula from an ordinary photograph.

Measure comparably

BYK's industrial-coatings reference distinguishes colour/gloss and colour-difference equations and discusses metamerism S27. A single Delta E value is incomplete without the formula, measurement geometry, illuminant/observer, sample and acceptance context. Do not treat Delta E 76 and Delta E 2000 as numerically interchangeable or impose one universal pass threshold.

Use consistent sample preparation, backing, opacity, thickness, texture and instrument settings when comparing readings. Establish the relevant visual acceptance conditions and reference sample. Check calibration and instrument capability for the actual finish. Gloss measurements need their geometry and units, and gloss does not fully describe haze, orange peel or distinctness of image. Retrieve the relevant method rather than inventing a conversion between sheen names and gloss units.

X-Rite's instrument manual defines metamerism through a change in matching under different illuminants S28. The manual's graphics-instrument workflow is not an automotive measurement standard. Verify the instrument/procedure suited to the application.

Practical matching workflow

1. Identify the target, colour code/variant and finish, plus ageing and previous repairs.
2. Inspect under the agreed controlled lighting and more than one relevant light source.
3. Prepare a sample using the intended substrate, primer/groundcoat, material batch and application.
4. Assess opacity, colour, effect orientation, texture and gloss after the specified dry/cure period.
5. Adjust only through the approved tinting/formulation process; retain records and samples.

A sample matching in daylight but diverging indoors can be metamerism; differences in gloss/texture or viewing angle can also matter. Do not prescribe a tint adjustment until these causes are separated. A monitor, rendered colour swatch, photograph or RAL/NCS reference name alone is not a physical colour approval.

Hiding and finish choice

Distinguish spreading rate at required film thickness from opacity over a contrasting substrate. Pigment dispersion and optics matter S06. A darker/new colour or pronounced substrate contrast may affect the coating process; do not invent coat counts. Balance the required appearance with surface condition, cleaning, maintenance and system suitability.

Safety, handling and environment

Identify actual hazards

Read the exact regional SDS, label, application instructions and equipment manual. Component hazards can differ from the mixed/cured material. Waterborne, low odour, low VOC, 1K, solvent-free and cured-to-touch are not equivalent to harmless.

Match precautions to the task, scale and exposure: vapour/aerosol, skin/eye contact, dust, fire/explosion, sensitisation, oxygen deficiency, confined spaces and high-pressure equipment. Consult competent occupational safety expertise for workplace controls. Do not prescribe a respirator or glove solely from a generic coating name.

Spraying and urgent situations

UK HSE's motor-vehicle guidance says filtering respirators are unsuitable for spraying isocyanate paints and specifies air-fed breathing apparatus S35. Explain its jurisdiction and task scope; do not present it as South African law. Do not assure a user that an organic-vapour cartridge, a disposable mask, an open garage door or absence of smell makes isocyanate spraying safe. Appropriate controlled spraying facilities, breathing-air arrangements and trained supervision need competent assessment. Keep people out of spray mist and respect documented booth-clearance procedures.

High-pressure injection can look small but needs urgent care. The Graco/Airlessco manual warns against treating it as a simple cut S39. If injection is suspected, advise immediate emergency medical assessment and identify the material/equipment to clinicians. Do not delay while researching toxicity or provide a home-treatment plan.

For breathing difficulty or serious chemical exposure, prioritise emergency assessment, movement away from exposure if safe and the exact SDS first-aid guidance. Do not enter an unsafe space to rescue someone.

Surface work, mixing and storage

Assess potential lead/chromate coatings, asbestos-containing substrates, silica and combustible dust before sanding, grinding, blasting or heating. Do not recommend uncontrolled dry abrasion, burning or improvised chemical stripping of unknown hazardous coatings. Follow pressure-relief and isolation procedures before spray equipment maintenance.

Reactive mixes can generate heat; batch size, container geometry and temperature affect working time. Follow maker instructions. Do not increase hardener to accelerate cure, add solvent to expired material or seal an actively reacting waste batch without appropriate instructions.

Control ignition sources, incompatible storage, ventilation and spill containment according to SDS and site requirements. Select chemical-resistant PPE by documented permeation/task requirements. Do not use solvents to clean skin.

Jurisdiction and environmental claims

South Africa's Hazardous Chemical Agents regulations provide a GHS/SDS framework S37. Navigate SDS sections for hazards, handling/storage, exposure controls, physical properties, reactivity, disposal and transport. Confirm current law and workplace applicability rather than treating every SDS as a complete risk assessment.

The 2024 South African lead-in-paint regulations have defined scope, concentration basis and commencement provisions S36. Retrieve current official text/amendments when advising on compliance; do not reproduce a legal threshold without its basis or certify a product from its marketing claim.

Keep paint, solvent and contaminated residues out of drains, ground and water. Verify local collection/disposal and courier dangerous-goods acceptance; flash point or an SDS transport section alone is not a courier booking approval.

Assess sustainability using performance, application losses, maintenance/recoat cycle and relevant lifecycle/emissions evidence. Low VOC alone does not establish a universally safer or lower-impact system.

Coverage, film thickness and mixing calculations

Use verified product inputs or clearly labelled assumptions. These calculations check arithmetic, not product suitability or permission to use a recipe. Use consistent units.

Film build

For volume-solids fraction s and target dry thickness d in micrometres:

• WFT = d / s (micrometres).
• Theoretical spreading = 1000 × s / d (m²/L).
• If allowed thinner is t litres per litre original coating, approximate effective solids = s/(1+t), assuming additive volumes. Use mixed-product volume solids, not mass solids or a single component's solids. Account for practical losses separately. These equations follow volume conservation; Jotun's application guidance discusses thickness control and coating losses S22.

Area and quantity

Theoretical litres = area × coats / spread, where spread is per coat. Do not multiply coats again if the published coverage already represents a full system.

• Additional allowance a: practical litres = theoretical × (1+a).
• Loss fraction l of purchased material: practical litres = theoretical/(1-l).
• No allowance: set mode none and value 0. 20% additional and 20% loss are different. Do not apply both to the same loss. User-supplied pack sizes support mathematical rounding only, not an assertion about what a store sells.

For line marking, area = length × width in consistent metres. Subtract openings or add edges/complexity only as measured or stated. Different layers may have different consumption.

Ratios and thinner basis

For a 79:21 ratio by mass and a 10 kg total, A = 7.9 kg and B = 2.1 kg. This is an arithmetic example, not product authorisation.

For a ratio by volume, distinguish the base volume, activated mixture and final ready-to-use volume. Identify whether thinner is specified as a fraction of base or activated material. 4:1 plus 10% of activated material is not the same as 10% of base. For a final target, solve backwards rather than adding thinner on top of that target. Ratios do not convert from mass to volume without component densities.

Density

Net mass = volume × density. Add verified can/carton/pallet tare separately; component density, mixed density and colour-specific values may differ. Never infer shipping weight from nominal litres alone.

Raw-material stoichiometry

Theoretical parts curing agent per hundred resin at 1:1 reactive equivalents: 100 × AHEW/EEW S07. Check as-supplied basis, blends, reactive diluents and supplier-selected stoichiometry. Do not substitute this for a finished coating's manufacturer ratio.

Show dimensional arithmetic explicitly and independently check it. Arithmetic does not validate dew point, service life, moisture limits, compatibility, regulatory compliance or certification.

Worked arithmetic examples

These are hypothetical inputs, not a product prescription.

• At 60% mixed-product volume solids and a target DFT of 120 micrometres, unthinned WFT = 120/0.60 = 200 micrometres. Theoretical spreading = 1000 × 0.60/120 = 5 m²/L.
• For 120 m², two coats and 8 m²/L per coat, theoretical quantity = 30 L. A 20% additional allowance gives 36 L. If instead 20% of purchased material is lost, required quantity = 30/0.80 = 37.5 L. With hypothetical 5 L packs, either result rounds up to eight packs, or 40 L.
• For exactly 1 L ready-to-use material at a hypothetical 4:1 ratio by volume plus 10% thinner measured on activated material, activated volume = 1/1.10 = 0.909091 L. Base = 0.727273 L, hardener = 0.181818 L and thinner = 0.090909 L. Only use this basis if the actual product instructions specify it.
• At a declared density of 1.3 kg/L, 5 L weighs 6.5 kg net. Packaging tare must be added separately for shipping.

Sources and document versions

Checked on 31 October 2026. IDs in the modules refer to these records. 'Reviewed' means relevant text/sections were opened and considered, not that every page was read, that a standard was purchased, or that a manufacturer approved this reference. Links are discovery/evidence routes; retrieve current applicable documents before product or compliance decisions.

| S42 | Star Paint, QD Spraying Enamel | Page date unstated | Southern Africa; regional applicability unverified | Product-page chemistry description reviewed; not current TDS/SDS validation. | | S43 | Atlas Paints, YEKAShield WB QD Metal Paint | Page date unstated | South Africa | Product-page chemistry description reviewed; not current TDS/SDS validation or a comparison endorsement. |