Prepare Surfaces for Painting
CPCCPD3021A (D7385)
Topic 1:
Surfaces
Contents
Introduction............................................................................................................................................................................3
Substrates Menu ....................................................................................................................................................................3
Softwood Timbers ....................................................................................................................................................4
Hardwood Timbers..................................................................................................................................................4
Particle Board (Chipboard) ....................................................................................................................................5
Hardwood (Sheeting) ..............................................................................................................................................5
Craftwood / MDF (Medium Density Fibreboard) ............................................................................................6
Plywood ......................................................................................................................................................................6
Gyprock Plasterboard .............................................................................................................................................7
Fibrous Plaster / Plaster Glass ...............................................................................................................................7
Hard Plaster / Gypsum Plaster ..............................................................................................................................8
Fibre Cement (Hardi Sheet) ..................................................................................................................................8
Masonry.......................................................................................................................................................................9
Ferrous Metals...........................................................................................................................................................9
Non-Ferrous Metals.............................................................................................................................................. 10
Plastics (PVC) ......................................................................................................................................................... 10
Expanded Polystyrene .......................................................................................................................................... 11
Vermiculite .............................................................................................................................................................. 11
Glass Glazed Tiles ................................................................................................................................................. 12
End of Substrates ............................................................................................................................................................... 12
Substrate Defects Menu ................................................................................................................................................... 12
Lack of Adhesion ................................................................................................................................................... 13
Bleeding Stains ........................................................................................................................................................ 13
Dampness ................................................................................................................................................................ 13
Acidic Substrates ................................................................................................................................................... 14
Alkaline Substrates ................................................................................................................................................ 14
Efflorescence ........................................................................................................................................................... 15
Corrosive Substrates (Metal) ............................................................................................................................. 15
Mould & Mildew ..................................................................................................................................................... 15
Dry Rot .................................................................................................................................................................... 16
Wet Rot ................................................................................................................................................................... 16
Conclusion ........................................................................................................................................................................... 16
Credits - Funding................................................................................................................................................................ 16
Credits - Images ................................................................................................................................................................. 17
About the National VET E-learning Strategy .............................................................................................................. 17
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Introduction
Main Painter: Wood, plaster, cement, plastic… all of these different substrates - they’re driving me
crazy!
Helper Painter: It’s easy! Let’s take a look.
Main Painter: There are so many different types of surfaces we paint on. Can't we just paint them
all the same?
Helper Painter: But these surfaces differ greatly in composition and characteristic. You will need to
know how to tell them apart, what kind of prep is required, and select a suitable coating.
Main Painter: I wish there was only one type of surface we painters have to paint.
Helper Painter: I know what you mean. But how boring would that be? It's not that hard - let's go
through them one by one.
Substrates Menu
•
Softwood Timbers
•
Hardwood Timbers
•
Particle Board (Chipboard)
•
Hardwood (Sheeting)
•
Craftwood / MDF (Medium Density Fibreboard)
•
Plywood
•
Gyprock Plasterboard
•
Fibrous Plaster / Plaster Glass
•
Hard Plaster / Gypsum Plaster
•
Fibre Cement (Hardi Sheet)
•
Masonry
•
Ferrous Metals
•
Non-Ferrous Metals
•
Plastics (PVC)
•
Expanded Polystyrene
•
Vermiculite
•
Glass Glazed Tiles
Page 3 of 17
Softwood Timbers
Used for construction, and include Pine, Oregon, Cedar, etc.
Properties:
•
Porous, absorbent, soft, strong and straight.
Defects:
•
Resinous knots.
Preparation:
•
Sand and dust.
First coat:
•
Oil or water based primers.
•
Oil or water based clear coatings.
Example image:
•
Cedar
Hardwood Timbers
Used for construction and decorative purposes, panelling and veneering. Includes oak, ash, beech, jarrah,
karri, teak, etc.
Properties:
•
Porous, absorbent, hard, strong and durable.
Defects:
•
May contain sap if still ‘green’ (damp).
Preparation:
•
Sand and dust.
First coat:
•
Oil or water based primers.
•
Oil or water based clear coatings.
Example image:
•
Jarrah
Page 4 of 17
Particle Board (Chipboard)
Wood chips and resin firmly compressed at a high temperature. Used mainly for furniture and shelving.
Properties:
•
Rigid, dense, even textured, water-resistant chipboard used for flooring.
Defects:
•
Non-resistant chipboard will swell when wet.
Preparation:
•
Remove dust.
First coat:
•
Water based primer.
•
Water based clear coating.
Example image:
•
Chipwood
Hardwood (Sheeting)
Made from wood pulp, wood fibres and resin firmly compressed at a high temperature (e.g. masonite). Used
as a lining for walls, ceilings and panel doors.
Properties:
•
Porous, absorbent, hard, strong and durable.
Defects:
•
Very smooth.
Preparation:
•
Remove dust.
First coat:
•
Oil based primer or sealer.
•
Oil based clear coating.
Example image:
•
Masonite
Page 5 of 17
Craftwood / MDF (Medium Density
Fibreboard)
Fibreboard used for shelving, doors, furniture and mouldings. Has replaced chipboard in many situations.
Properties:
•
Strong/stable with uniform density and superfine finish.
Defects:
•
Waxy finish on surface. Resin used for manufacture contains formaldehyde, which is
carcinogenic.
Preparation:
•
Remove dust.
First coat:
•
Water based primer.
•
Water based clear coating.
•
NOTE: Oil bases could react with wax/resin.
Example image:
•
Customwood
Plywood
Thin veneers of wood glued together with the grain running at right angles. Used in furniture, doors and wall
panelling. Thickness between 3-25mm depending on the number of veneers or plies.
Properties:
•
Rigid, porous and absorbent.
Defects:
•
Varying texture.
Preparation:
•
Remove dust.
First coat:
•
Oil or water based primers.
•
Oil or water based clear coatings.
Example image:
•
Plywood
Page 6 of 17
Gyprock Plasterboard
A building material composed of a layer of gypsum plaster sandwiched between two layers of kraft paper.
Used extensively for lining walls and ceilings, replacing fibrous plaster sheets.
Properties:
•
Porous, very absorbent. It does not craze like fibrous plaster.
Defects:
•
Tends to show peaking at flush joints.
Preparation:
•
Remove dust.
First coat:
•
Water based sealer.
Example image:
•
Gyprock
Fibrous Plaster / Plaster Glass
A building material made of gypsum plaster and synthetic fibre. Together they form hard rigid sheeting or
decorative mouldings. Sheeting has been replaced by plasterboard.
Properties:
•
Porous, absorbent, smooth faced, chemically active due to a presence of alkali (usually where
jointed).
Defects:
•
Susceptible to warping, buckling and cracking.
Preparation:
•
Remove dust.
First coat:
•
Oil based sealer.
Example image:
•
Plaster glass
Page 7 of 17
Hard Plaster / Gypsum Plaster
Mixed and applied by trowel to provide a hard uniform finish to ceilings or walls.
Properties:
•
Porous, absorbent and chemically active.
Defects:
•
If moisture is present, this can lead to efflorescence. Other defects include saponification,
lime burn, poor adhesion of paints, hairline cracking, trowel marks and a loose chalky
surface.
Preparation:
•
Dust and check for moisture/pH levels.
First coat:
•
Oil based sealer.
Example image:
•
Hardwall plaster
Fibre Cement (Hardi Sheet)
A combination of cement silica, cellulose fibres and water. Available as piping, flat sheeting, corrugated
sheeting and planking. Used for exterior lining on timber/metal framed housing, eaves and fences.
Properties:
•
Porous and absorbent.
Defects:
•
Check for moisture.
Preparation:
•
Remove dust.
First coat:
•
Flat plastic/water or oil based sealer.
Example image:
•
Hardiflex
Page 8 of 17
Masonry
Masonry materials include bricks, stone, concrete and cement render.
Properties:
•
Porous, absorbent and chemically active. These materials contain alkaline salts and other
chemicals which may have a detrimental effect on some drying oils in paint.
Defects:
•
If moisture is present, this can lead to efflorescence. Other defects include saponification,
lime burn and poor adhesion of paints.
Preparation:
•
Remove dust and check moisture/pH levels. Concrete panels (tilt-up) must be checked for
bonding agents.
First coat:
•
Water based sealer or alkali resisting oil based sealer.
Example image:
•
Brick
Ferrous Metals
Metals containing iron, e.g. cast iron, wrought iron, mild steel, high tensile steel and stainless steel. Used for
structural purposes.
Properties:
•
Non-absorbent and corrodible.
Defects:
•
When iron and steel are exposed to oxygen and water, they quickly corrode and rust forms
on the surface. It is the iron content which causes the rust.
Preparation:
•
Degrease, wire brush, dust and apply rust converter.
First coat:
•
Metal primers (that contain zinc).
Example image:
•
Sheet iron
Page 9 of 17
Non-Ferrous Metals
Metals containing no iron, e.g. aluminium, zinc, copper, brass, bronze, lead, chromium, cadmium, tin,
zincalume, etc. Zinc-coated iron and steel may also be classed as non-ferrous metals, e.g. galvanised iron.
Used for structural and decorative purposes.
Properties:
•
Non-absorbent and corrodible.
Defects:
•
Non-ferrous metals can corrode when exposed to oxygen and water that contain impurities.
Fine, firmly adhering corrosion deposits are formed which inhibit and slow down the
corrosion process. Corrosion can be accelerated by contact with dissimilar metals, acid or
alkaline materials.
Preparation:
•
Dust and degrease.
First coat:
•
Etch primer or galvanised iron primer for galvanised iron.
Example image:
•
Zincalume
Plastics (PVC)
PVC (polyvinyl chloride) refers to synthetic materials available as mouldings or sheet form; they are usually
self-coloured white or grey. Painting is not necessary unless a particular colour is required, e.g. waste pipes
and downpipes. Used extensively for moulded spoutings, downpipes and waste pipes.
Properties:
•
Non-porous and non-absorbent. Smooth surface lacking adhesion.
Defects:
•
Release agents that remain on surface after manufacture.
Preparation:
•
Degrease and abrade.
First coat:
•
Oil or water based paints.
Example image:
•
PVC pipe
Page 10 of 17
Expanded Polystyrene
Polymerised styrene resin expanded into an extremely lightweight, insulative material which is used
extensively for ceiling tile panels.
Properties:
•
Porous and non-absorbent.
Defects:
•
Solvent borne paints may dissolve the polystyrene but can be used after sealing with a water
based paint.
Preparation:
•
Dust.
First coat:
•
PVA or water based paint.
Example image:
•
Polystyrene sheet
Vermiculite
Vermiculite refers to a group of hydrated laminar minerals which are aluminium iron magnesium silicates
resembling mica. Pre-mixed vermiculite plasters are available, either gypsum or cement based and can be
applied by hand but are usually sprayed to produce an attractive, decorative textured finish on concrete
ceilings.
Properties:
•
Porous, absorbent, clean to handle, non-abrasive, rot proof and good anti-condensation
properties.
Defects:
•
Vermiculite plasters are tough and resilient rather than hard. They will indent under impact
rather than crack and fall away.
Preparation:
•
Dust off with broom.
First coat:
•
Oil or water based paints.
Example image:
•
Formiculite
Page 11 of 17
Glass Glazed Tiles
Ceramic tiles have a hard glazed coating applied and fired under high temperatures. Normally not painted.
Used on floors and walls in wet and greasy areas.
Properties:
•
Non-porous and non-absorbent.
Defects:
•
They are usually very dense, smooth and shiny, providing very little adhesion for paint.
Preparation:
•
Do not sand as this will damage the surface. Degrease and abrade using water and whiting
or methylated spirit and whiting. Remove all traces of whiting and paint as soon as possible.
Do not allow further contamination.
First coat:
•
The material used must possess good adhesive properties. There are paints specially
formulated for tiles and laminates.
Example image:
•
Glazed tiles
End of Substrates
Main Painter: Wow, there sure are a lot of substrates! Now that I know them, can we start
painting?
Helper Painter: Not so fast! Not all surfaces come in mint condition. You’ll also need to know how
to identify problems with substrates and how to prevent and treat them.
Substrate Defects Menu
1. Lack of Adhesion
2. Bleeding Stains
3. Dampness
4. Acidic Substrates
5. Alkaline Substrates
6. Efflorescence
7. Corrosive Substrates (Metal)
8. Mould & Mildew
9. Dry Rot
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10. Wet Rot
Lack of Adhesion
Description:
•
Failure of a coating or material to adhere to a substrate.
Common Causes:
•
Painting over poorly prepared surfaces, e.g. damp and greasy surfaces, smooth and shiny
surfaces, etc.
•
Formation of rust or efflorescence under painted surfaces.
•
Expansion and shrinkage of painted surfaces.
Prevention / Treatment:
•
Ensure that substrates are correctly prepared – they are clean, dry and free of contaminates,
and correctly sealed or primed before application of coatings.
Bleeding Stains
Description:
•
Soluble stains that show through a paint coating.
Common Causes:
•
Occurs when materials such as lipstick, crayon, tar and some inks permeate paint coatings
and show on the surface.
•
Can also be caused by painting substrates contaminated by smoke and painting over oily or
knotty resinous timbers.
Prevention / Treatment:
•
Where possible, remove contaminates then seal back with either a stain sealer or a
proprietary bleed sealer.
Dampness
Description:
•
Dampness is either due to weather conditions or structural dampness. It can be a problem
for paint coatings, causing a lack of adhesion, staining and eventual peeling of the coating.
Common Causes:
•
In new buildings, moisture is present in brickwork, plaster, concrete and masonry. Where
an oil based system is used, sufficient time must be allowed for this moisture to dry out
prior to painting.
Page 13 of 17
•
Rain penetration due to faulty roof flashing, broken tiles, blocked guttering or porous
external substrates.
•
Rising damp due to absence of or defects in damp proof courses.
Prevention / Treatment:
•
Ensure adequate protection of substrates from moisture penetration and ensure that there
is adequate ventilation.
Acidic Substrates
Description:
•
Either naturally occurring or environmental factors that lodge acidic compounds on a
surface.
Common Causes:
•
Red Pine, Oak and Cedar are timbers with high acid and oil content.
•
Cooking fumes in kitchens and pollutants in industrial areas can also be acidic and cause
breakdown of some coatings.
Prevention / Treatment:
•
For decoration of acidic timbers, use an oil stain finish. Treat acid affected surfaces like
commercial kitchen walls by washing down with a mild alkaline solution (e.g. sugar soap).
Alkaline Substrates
Description:
•
Substrates that contain lime or cement, e.g. cement render, concrete, brickwork, stone,
plaster, etc. Also substrates that had paint removers applied or treated with caustic
solutions can also be alkaline.
Common Causes:
•
Painting over alkaline surfaces (e.g. plaster) can cause breakdown of adhesion in a coating.
Painting alkaline surfaces with an oil paint also causes saponification (the reaction between an
oil or resin and an alkaline substrate, forming a soapy substance).
Prevention / Treatment:
•
Allow sufficient drying time of the new substrate. Use a moisture meter to ensure surfaces
are dry enough to be painted and conduct a pH test (do not paint if pH level is over 10).
Alternatively, neutralise alkali by treating with mild acid then seal with an alkali resistant
sealer or use an acrylic paint system.
Page 14 of 17
Efflorescence
Description:
•
A white crystalline deposit forming on masonry surfaces such as bricks, cement render,
plaster and concrete.
Common Causes:
•
Moisture causes water soluble salts to rise to the surface. When moisture evaporates, salts
remain on the surface.
Prevention / Treatment:
•
Rectify the cause of moisture contacting the affected substrate. Remove surface
efflorescence by dry brushing. Leave to dry thoroughly. If salts do not resurface, apply an
alkali resisting sealer (e.g. a pigmented oil based sealer).
Corrosive Substrates (Metal)
Description:
•
Corrosion is the deterioration of a metal.
Common Causes:
•
Chemical attack when metal is exposed to the action of moisture, oxygen, acid or alkali.
•
Corrosion can also be caused by contact between dissimilar metals, e.g. iron and tinplate.
Prevention / Treatment:
•
Avoid contact between dissimilar metals and use an appropriate metal primer followed by a
coating system that will resist moisture.
Mould & Mildew
Description:
•
Fungal growth that multiplies and feeds on organic matter.
Common Causes:
•
This is common in poorly ventilated or damp buildings.
Prevention / Treatment:
•
Trace and remedy the cause of dampness. Remove mould and mildew by washing with an
anti-fungicidal solution or a 3:1 mixture of water and household bleach. Leave for 10-20
minutes then rinse off with clean water. Repaint with a paint containing a mould inhibitive
agent. If there is a mould stain evident, a suitable oil based sealer will be required prior to
applying anti-fungal finishing coats.
Page 15 of 17
Dry Rot
Description:
•
A fungus that destroys timber. In its early stages, the timber is excessively wet, spongy and
covered with fine silvery strands. When timber has dried out, it is brittle and has no
strength.
Common Causes:
•
The fungus develops when timber has a moisture content above 20%, in humid atmospheres
and poor ventilation.
Prevention / Treatment:
•
Trace and remedy the cause of dampness. Increase ventilation and remove all infected
timber. Treat adjacent timber and new timber with wood preservative or a coating system
that resists moisture.
Wet Rot
Description:
•
Wet rot develops in timber containing 50-60% moisture content. Timber is darkened and
cracked with the grain. It becomes spongy and excessively wet beneath a seemingly sound
surface.
Common Causes:
•
External timbers where flaking paint allows penetration of excessive moisture, e.g. window
sills that are consistently wet.
Prevention / Treatment:
•
Trace and remedy the cause of dampness. If rotting is not too severe apply timber primer
followed by subsequent coatings. For severe cases, remove affected timber, replace with
new primed timber and apply subsequent coatings.
Conclusion
Main Painter: Wow, that was a lot to take in. I’m glad I checked everything out.
Helper Painter: Now that you’re more familiar with different substrates and their defects, let’s see
what prep you’ll need to do before we start painting.
Credits - Funding
This project was made possible through funding from the National VET E-learning Strategy 20122015, a joint initiative of the Australian and state and territory governments
(http://flexiblelearning.net.au).
Page 16 of 17
For further information on the National VET E-learning Strategy, please contact the FLAG
Secretariat:

Phone: (03) 9954 2700

Email: flag_enquiries@natese.gov.au

Website: flexiblelearning.net.au
Topic 1: Surfaces (Prepare Surfaces for Painting), © Commonwealth of Australia (Department of
Industry, Innovation, Climate Change, Science, Research and Tertiary Education), 2013.
(http://creativecommons.org/licenses/by/3.0/au)
Credits - Images
All images used in this resource are owned by Polytechnic West. © Polytechnic West 2013
Information within this resource was current at 2013.
About the National VET E-learning Strategy
This project was made possible through funding from the 2012-2015 National VET Elearning Strategy (‘the Strategy’). The Strategy is a joint initiative of the Australian and state
and territory governments aimed at strengthening the Australian training sector’s use of new
learning technologies; stimulating innovative approaches to increasing participation in
training and employment, and improving the skill levels of the Australian workforce
(http://flexiblelearning.net.au).
For further information on the National VET E-learning Strategy, please contact the FLAG
Secretariat:
Phone: (03) 9954 2700
Email: flag_enquiries@natese.gov.au
Website: flexiblelearning.net.au
Topic 1: Surfaces (Prepare Surfaces for Painting), © Commonwealth of Australia (Department of Industry,
Innovation, Climate Change, Science, Research and Tertiary Education), 2013.
With the exception of the Commonwealth Coat of Arms, the Department’s logo, any material protected by a trade
mark and where otherwise noted all material presented in this document is provided under a Creative Commons
Attribution 3.0 Australia (http://creativecommons.org/licenses/by/3.0/au/) licence.
Page 17 of 17