Why Preparation Comes First
Paint performs best when it is applied to a clean, dry and stable surface.
If the surface is dirty, loose, damp or poorly prepared, the new coating may fail even when a high-quality paint is used.
Preparation creates a suitable base for the new paint system. It also gives the contractor an opportunity to identify problems that should be addressed before coating begins.
The required preparation depends on:
- the surface material;
- the condition of the existing paint;
- the age of the property;
- exposure to weather or moisture;
- the coating system being applied;
- the standard of finish required.
Not every project requires the same level of preparation.
A well-maintained surface may need only cleaning, light sanding and minor filling. A deteriorated surface may require substantial scraping, stripping, repairs and priming before it can be repainted.
Cleaning the Surface
Paint should not be applied over dirt, dust, grease, mould or chalking residue.
Exterior surfaces are commonly washed before preparation begins. Depending on the property, this may involve water blasting, soft washing, brushing or chemical treatment.
The cleaning method should suit the building and the surface.
High pressure may be appropriate for durable exterior areas, but it must be used carefully around windows, weatherboards, roof edges, internal gutters and other places where water could enter the building.
Interior surfaces may require:
- dust removal;
- grease cleaning;
- mould treatment;
- washing around kitchens and bathrooms;
- removal of smoke or other surface contamination.
Cleaning is not a substitute for preparation, but proper preparation cannot begin until the surface is clean.
Removing Loose or Failed Paint
New paint should not be applied over a coating that is already peeling, flaking or losing adhesion.
Loose paint must be removed until the remaining coating is firm enough to support the new system.
Depending on the condition of the surface, this may involve:
- scraping;
- mechanical sanding;
- heat-assisted removal;
- chemical stripping;
- complete paint stripping.
Complete stripping is not required for every repaint.
It may be necessary where multiple layers have failed, the existing coating is unstable or the desired finish cannot be achieved by local preparation alone.
The purpose is not to remove paint simply because it is old. The purpose is to remove material that cannot reliably support the next coating system.
Sanding
Sanding serves several purposes.
It can:
- smooth rough edges where old paint has been removed;
- reduce raised grain or surface defects;
- dull glossy coatings;
- improve adhesion between coats;
- prepare fillers and repaired areas;
- improve the final appearance.
The amount of sanding depends on the condition of the surface and the expected finish.
A serviceable exterior repaint does not always require every surface to be sanded completely smooth. Detailed interior joinery or high-gloss finishes may require much more careful sanding.
The preparation standard should match the agreed scope and finish.
Filling Holes, Cracks and Gaps
Small defects are normally repaired before painting.
This may include:
- nail holes;
- minor cracks;
- dents;
- open joints;
- gaps around trims;
- damaged plaster;
- local imperfections in timber.
The correct filler must suit the material, location and expected movement.
A rigid interior filler may not be suitable for an exterior joint that expands and contracts. Likewise, a flexible gap filler is not intended to rebuild damaged timber or replace plaster repairs.
Larger defects may require building, plastering or carpentry work rather than ordinary painting preparation.
A quotation should make clear where minor filling ends and additional repair work begins.
Repairs Before Painting
Painting can protect and improve a surface, but it cannot correct every underlying problem.
Repairs may be required where there is:
- rotten timber;
- damaged weatherboards;
- loose cladding;
- failed sealants;
- water-damaged plaster;
- corrosion;
- leaking joints;
- unstable substrates.
Painting over damaged material may temporarily improve its appearance without resolving the cause of the problem.
The damaged area should first be assessed and repaired using a method appropriate to the substrate.
Where repairs are outside the agreed painting scope, the contractor should identify them and explain whether they require a separate price or another trade.
What Is a Paint System?
A paint system is the complete sequence of products applied to a surface.
It may include:
- surface preparation;
- primer or sealer;
- undercoat;
- finish coats.
Not every project requires every stage.
The correct system depends on the material, the existing coating and the conditions the finished surface will face.
For example, a straightforward repaint over a sound compatible coating may require local priming and two finish coats.
A bare, stained, glossy, weathered or difficult surface may require a more specialised system.
The important question is not simply:
“Which paint will be used?”
It is:
“Which complete system is suitable for this surface?”
Primer
Primer is used to prepare a surface for the coats that follow.
Depending on the product, a primer may:
- improve adhesion;
- seal porous material;
- protect bare timber or metal;
- reduce uneven absorption;
- isolate difficult surfaces;
- support the finish coats.
Different substrates require different primers.
Examples may include primers for:
- bare timber;
- galvanised metal;
- previously painted metal;
- masonry;
- plaster;
- stained surfaces;
- difficult or glossy coatings.
Using an unsuitable primer can reduce adhesion or create compatibility problems within the system.
Sealer
A sealer controls the absorption of porous or repaired surfaces.
It may be used on:
- new plaster;
- repaired plaster;
- porous masonry;
- fibre cement;
- water-stained areas;
- surfaces with uneven porosity.
Without suitable sealing, finish paint may absorb unevenly and produce patchy colour or sheen.
Some products combine sealing and priming functions, while others are designed for a specific purpose.
The product should be selected based on the actual surface rather than the label alone.
Undercoat
An undercoat creates a more uniform base for the finish coats.
It may help with:
- coverage;
- colour change;
- adhesion;
- stain blocking;
- smoothing;
- building the required coating thickness.
Undercoats are particularly important on some timber surfaces, previously varnished joinery, difficult colours and surfaces requiring additional isolation.
One coat may be sufficient in some situations. Other surfaces may require two coats before the finish can be applied.
Oil-based undercoats are still used where strong adhesion, stain blocking or isolation is required. However, the correct product depends on the surface and the finish system being applied over it.
Finish Coats
Finish coats provide the final colour, appearance and surface protection.
Most painting systems use two finish coats to achieve:
- even colour;
- consistent sheen;
- proper coverage;
- adequate film build;
- improved durability.
A single finish coat may not provide the appearance or coating thickness expected from a complete system.
The finish paint should also suit the location.
Interior walls, bathrooms, joinery, exterior weatherboards, roofs and decks are exposed to different conditions and require products designed for those uses.
Why the Number of Coats Matters
The number of coats should be based on the requirements of the system, not treated as a marketing statement.
Additional coats may be required because of:
- a major colour change;
- a porous surface;
- difficult coverage;
- repaired areas;
- previous coating failure;
- the need for additional film thickness;
- product specifications.
More coats do not automatically mean a better job.
Applying unnecessary coats cannot compensate for poor preparation or the wrong primer.
Likewise, reducing the specified number of coats may affect colour consistency, durability and compliance with the paint manufacturer’s system.
The full sequence should make technical sense.
Paint Compatibility
New coatings must be compatible with the existing surface and with each other.
Compatibility problems can occur when:
- water-based paint is applied over a glossy coating without preparation;
- the wrong primer is used on galvanised metal;
- a flexible coating is applied over an unstable layer;
- a finish coat reacts with the product below it;
- paint is applied over silicone or contamination;
- a coating is used outside its intended application.
The contractor should identify the existing surface where possible and choose a system that can bond to it.
Where the existing coating is uncertain, testing or additional preparation may be necessary.
Product Selection
A suitable product should be chosen for the surface and exposure conditions.
The most expensive paint is not automatically the correct paint for every project.
Product selection may depend on:
- interior or exterior use;
- exposure to sun and rain;
- moisture;
- required washability;
- substrate movement;
- existing coatings;
- gloss or sheen;
- application method;
- expected maintenance.
The manufacturer’s product range is only one part of the decision.
The correct preparation and application are equally important.
Application Conditions
Paint should be applied under suitable conditions.
Exterior painting may be affected by:
- rain;
- dew;
- low temperatures;
- excessive heat;
- direct sun;
- strong wind;
- moisture within the surface.
Interior painting may be affected by:
- poor ventilation;
- low temperature;
- high humidity;
- dust;
- condensation;
- insufficient drying time.
A surface may feel dry while still containing too much moisture for painting.
The contractor should allow suitable drying and recoat time between washing, preparation, priming and finish coats.
Rushing the system can affect adhesion and curing.
Drying Time and Curing Time
Drying and curing are not the same.
A coating may be dry enough to touch or recoat but may not yet have reached its final hardness and durability.
Full curing can take longer, particularly for:
- enamel paints;
- high-build coatings;
- epoxy systems;
- coatings applied in cool or humid conditions.
During the curing period, painted surfaces may be more vulnerable to marking, blocking, moisture or heavy cleaning.
Homeowners should follow the contractor’s instructions before using freshly painted doors, windows, shelves, floors or other high-contact surfaces.
What Does a Painting Warranty Cover?
A painting warranty normally covers defects directly related to the contractor’s workmanship.
Depending on the written terms, this may include problems such as:
- peeling caused by inadequate preparation;
- missed areas;
- coating failure caused by incorrect application;
- failure to complete the agreed paint system.
A warranty does not normally mean that every painted surface will remain unchanged for the entire warranty period.
Paint is exposed to weather, movement, moisture, wear and building conditions that may be outside the painter’s control.
The exact coverage should be written clearly.
What May Not Be Covered?
Common warranty exclusions may include:
- water leaks;
- ongoing moisture;
- structural movement;
- substrate failure;
- timber movement or resin bleed;
- corrosion originating below the coating;
- damage caused by other trades;
- impact or physical damage;
- mould caused by ventilation or moisture conditions;
- areas repaired or altered after completion;
- maintenance not carried out by the owner;
- failures in existing coatings below the new paint system.
These exclusions should be reasonable and relevant to the property.
A warranty should not be used to hide poor workmanship, but it also cannot make the painter responsible for every future building problem.
Manufacturer Warranty vs Workmanship Warranty
These are not the same.
A paint manufacturer may provide a product warranty when its coating is used according to the specified system.
The painting contractor may provide a workmanship warranty covering the preparation and application completed by the contractor.
A product warranty may not apply when:
- the surface was unsuitable;
- the specified preparation was not completed;
- incompatible products were used;
- the coating was applied outside the required conditions;
- the underlying building material failed.
The homeowner should understand who is providing the warranty and what each party is responsible for.
What Makes a Warranty Meaningful?
The length of a warranty is only one consideration.
A useful warranty should clearly state:
- who provides it;
- what work is covered;
- which surfaces are included;
- how long the coverage lasts;
- what is excluded;
- what maintenance is required;
- how a claim should be made;
- what remedy will be provided if the claim is accepted.
A long warranty with vague terms may offer less protection than a shorter warranty with clear and realistic coverage.
The warranty should also match the condition of the property and the selected paint system.
Maintenance After Painting
Even a correctly prepared and painted surface requires maintenance.
Exterior surfaces should be inspected and cleaned periodically to remove:
- dirt;
- salt;
- mould;
- airborne contamination;
- debris collecting around joints or gutters.
Small failures should be repaired before they develop into larger problems.
Interior surfaces should be cleaned using methods suitable for the selected paint and sheen.
Harsh chemicals or abrasive cleaning may damage some finishes.
Keeping records of the products and colours used can also make future maintenance and touch-ups easier.
Questions to Ask Your Painter
Before accepting a quotation, consider asking:
- What preparation is included?
- Will loose or failed paint be removed?
- Is complete paint stripping required anywhere?
- Which primers or undercoats will be used?
- Are any areas likely to require two undercoats?
- How many finish coats are included?
- Are the proposed products suitable for the existing surface?
- How will moisture or coating failure be addressed?
- What repairs are included?
- What warranty is provided?
- What conditions are excluded from the warranty?
- What maintenance will be required after completion?
The answers should be reflected in the written quotation wherever they affect the price or scope.
Key Takeaway
Preparation, paint systems and warranties should not be considered separately.
Good preparation creates a stable base.
The correct paint system protects that base and provides the required finish.
A clear warranty explains what the contractor will stand behind after the project is completed.
The strongest result comes from all three working together.