Prepare Surfaces for Painting
CPCCPD3021A (D7385)
Topic 2:
Preparation
Contents
Introduction............................................................................................................................................................................4
Stage 1: Evaluation ................................................................................................................................................................4
New Surface...............................................................................................................................................................4
Moisture Test ................................................................................................................................................4
pH Test ...........................................................................................................................................................5
Pre-Wallpapered Surface ........................................................................................................................................6
Manual .............................................................................................................................................................6
Steam Stripper ..............................................................................................................................................7
Pre-Painted Surface ..................................................................................................................................................7
Sound vs. Unsound ......................................................................................................................................8
Adhesion Test ...............................................................................................................................................8
Unsound Surface Prep ................................................................................................................................9
Hand Methods ..................................................................................................................................9
Mechanical Methods ..................................................................................................................... 10
Disc Sander ........................................................................................................................ 10
Orbital Sander ................................................................................................................... 10
Belt Sander ......................................................................................................................... 11
Heat Methods ................................................................................................................................ 12
Burning Off Tools............................................................................................................. 12
Heat Guns (Hot Air Guns) ............................................................................................ 13
Chemical Methods ........................................................................................................................ 13
Acids & Alkalis................................................................................................................... 13
Paint Remover................................................................................................................... 14
Unsound Surface Prep - End ............................................................................................................................... 15
End of Stage 1: Evaluation ................................................................................................................................................ 15
Stage 2: Cleaning ................................................................................................................................................................ 15
Washing – Introduction ....................................................................................................................................... 16
Washing – Common Types .................................................................................................................... 16
Washing – Procedure............................................................................................................................... 16
Washing – Solvent Cleaning ................................................................................................................... 17
Washing – Acids & Alkalis ...................................................................................................................... 18
Acids & Alkalis: Common Trade Types .................................................................................. 18
Abrading – Introduction ...................................................................................................................................... 18
Abrading – Methods ................................................................................................................................. 19
Abrading – Common Types ................................................................................................................... 19
Silicon Carbide Paper (Wet / Dry) ......................................................................................... 19
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Production Paper .......................................................................................................................... 20
Garnet Paper ................................................................................................................................. 20
Zinc Stearate (Dry Lube) ............................................................................................................ 20
Wire or Steel Wool..................................................................................................................... 21
Rubbing & Polishing Compounds .............................................................................................. 21
Filling/Stopping – Introduction ........................................................................................................................... 21
Filling – Filling Materials ........................................................................................................................... 22
Filling – Acrylic Fillers............................................................................................................................... 22
Stopping – Stopping Materials ................................................................................................................ 23
Stopping – Procedure............................................................................................................................... 24
Conclusion ........................................................................................................................................................................... 25
Credits - Funding................................................................................................................................................................ 25
Credits - Images ................................................................................................................................................................. 25
About the National VET E-learning Strategy .............................................................................................................. 26
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Introduction
Main Painter: Looks like this wall needs a bit of work before we can start painting.
Helper Painter: It all depends on the prep work!
Main Painter: Preparation? No worries, I’ve got my scraper, my duster and a piece of sandpaper in
my back pocket. Prep will be done in no time!
Helper Painter: Actually, there is a lot more to preparation than just sanding a surface down and
dusting it.
Main Painter: Like what?
Helper Painter: It all depends on the condition of the surface and what’s already on it.
Stage 1: Evaluation
The first stage to preparation is to evaluate, test and get the surface ready for cleaning.
Click on each category of surfaces below to learn more:
•
New Surface
•
Pre-Wallpapered Surface
•
Pre-Painted Surface
New Surface
If you’re dealing with a new surface (i.e. one which has not been painted or wallpapered before), you
may have to conduct the following tests to ensure that the surface is ready for painting.
Click on each of the tests below to learn more:
•
Moisture Test
•
pH Test
Moisture Test
Purpose:
Surfaces that contain moisture can affect adhesion of paint and the coating can crack in the short
term and peel in the long term. Moisture on masonry surfaces can make them more alkaline and
timber surfaces more acidic.
Usual Surfaces:
Masonry surfaces such as bricks, concrete and plaster, as well as gyprock and wood can absorb
moisture.
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Tools:
A moisture meter can be used to determine the level of moisture on the surface.
Method:
1. Turn the machine on.
2. Apply to surface making sure all prongs have contact.
3. Take the reading.
Readings:
Follow the manufacturer’s instructions. In most cases, readings are shown in percentage (%).
Usually a surface can be painted when moisture levels are 14% or below. Surface readings above
14% need more time to dry.
pH Test
Purpose:
High levels of acid or alkaline will affect a coating. In the short term, burn marks may show through
the coating; in the long term, it may cause paint to saponify (coating changes into a soap-like state)
and the coating may peel.
Usual Surfaces:
Masonry surfaces such as bricks, concrete, plaster and stone which may be alkaline and timber
surfaces which may be acidic.
Tools:
A pH (or Litmus) test kit can be used to determine a surface’s acidity or alkalinity levels.
Method:
1. Apply a strip of Litmus paper to a surface and wet with distilled water. Allow the water to
be absorbed.
2. Wait for approx. 30 sec. The paper will change colour depending on the surface’s alkalinity
or acidity.
3. Compare with the scale/legend supplied by the manufacturer.
Readings:
Follow the manufacturer’s instructions. Readings between1-6 indicates acidity, and 8-14 indicates
alkalinity. A reading between 7 (neutral) and 10 is ideal for painting.
Video:
Watch this video demonstrating how to conduct a pH Test.
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Pre-Wallpapered Surface
Where surfaces have a wall covering, it is necessary to remove the wallpaper prior to any painting
work.
•
If the paper is strippable vinyl, the vinyl coating can be removed very easily by picking at
the bottom edge of each strip of wallpaper and peeling the whole strip off the wall. The
backing paper can then be removed using either of the two methods below.
•
Plastic coated vinyl is a cheaper type of paper that is sprayed with a clear coating during
manufacture. In this case, use either of the two methods below.
Click on each method to learn more:
•
Manual
•
Steam Stripper
Manual
Equipment:
•
Liquid wallpaper stripper.
Steps:
1. Mix the stripper in hot water to the manufacturer’s recommendations.
2. Apply the stripper solution to the wallpaper with a suitable brush or sponge.
3. Soak the entire wall surface twice.
4. Allow time for the solution to soak into the paper.
5. Scrape off the paper with a broad blade stripping knife.
6. Wash down the stripped area with warm water to remove all traces of adhesive and paper.
Notes:
If the paper is difficult to remove:
•
Make a series of knife cuts across the paper to allow the solution to soak in. Be careful to
cut the paper only as damage to the plaster wall is difficult to repair.
•
A stiff wire brush is a useful alternative to scratch the surface.
•
Resoak the surface several times.
•
If procedure is unsuccessful, use a steam stripper.
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Steam Stripper
Equipment:
A steam stripper consists of a water tank that boils water to produce steam. Steam transfers down
a hose to a steaming plate that is held against the wall covering to soften the adhesive.
Steps:
1. Fill tank with hot water to indicated level.
2. Reseal the filler cap tightly.
3. Switch on and allow time for steam to come through steam plate.
4. Hold the plate directly against the wall covering until it softens.
5. When softened, move the steaming plate to the next position and strip off softened section
with stripping knife.
6. Repeat until all paper is removed.
7. Wash down stripped area with warm water to remove all traces of adhesive and paper.
Notes:
•
Before the boiler reaches full steam, water will drip from the plate. Place over bucket or on
a folded drop sheet to avoid water damage.
•
Some papers may take longer than others to soften.
Safety Tips:
•
Keep power/gas connections in safe condition.
•
Do not let water level drop below safe operating levels.
•
Keep the steam hose free of kinks or bends to prevent blockage and safety valve blow out.
•
Be careful when refilling as the filler cap will be very hot. Steam may escape and burn.
•
Always reseal the filler cap tightly.
•
Never leave the steam stripper unattended whilst it is operating.
Pre-Painted Surface
If a surface is pre-painted, it does not mean it can be painted again with confidence. Pre-painted
surfaces also need to be evaluated before painting.
Occupational Health & Safety (OHS)
A painter also needs to be aware of the serious health issues associated with preparing pre-painted
surfaces which may contain lead or asbestos. Please refer to the OHS topic for more information.
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Sound vs. Unsound
A pre-painted surface can be categorised as either sound or unsound.
Sound Surfaces
Sound surfaces are surfaces that are in a firm, solid condition. They might be powdery to touch and
have a dull or flat appearance. A few areas might flake as a result of corrosion or dampness, etc.,
but essentially the coating is firmly adhered to the surface.
In some cases, a coating might not show any signs of flaking, but may have already lost its adhesion
to the surface. To check, an adhesion test can be conducted.
Unsound Surfaces
Unsound surfaces are previously painted surfaces that have completely broken down due to
overexposure to the elements. Surfaces may show severe signs of flaking, peeling, blistering and
cracking.
These surfaces may require paint removal as a means of creating a solid base before commencing
repaint procedures.
Surfaces in this condition require extensive time in their preparation. Failure to provide adequate
preparation will greatly limit the lifespan of the new coating to be applied.
Adhesion Test
An adhesion test, also called a “cross hatch” test, is used to check whether a pre-painted surface is
sound or unsound, i.e. how well the current coating has adhered to the surface. This test can be
carried out on any surface.
•
If a surface is unsound, you will need to know how to remove the current coating (if
required) before a new coating can be applied.
•
If the surface is sound, no further work is required. You can skip straight to the second
stage of preparation.
Purpose:
To check whether a pre-painted surface is sound or unsound.
Tools:
A sharp knife and strong masking tape.
Method:
1. Use the sharp knife to score the surface in a cross hatch design.
2. Place a strip of masking tape firmly over the entire cross hatch.
3. Peel tape off in a quick action, keeping your hands close to the surface.
4. Inspect tape and note how much paint has come off.
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Readings:
•
If significant amounts of paint comes off, this suggests that the coating is unsound and needs
to be removed.
•
If only a minute amount of paint comes off, then it suggests a sound surface.
Note:
Conduct the test in a variety of places, as paint may be unsound only in certain areas, such as
bottom of walls above skirting boards, and greasy or moist areas.
Video:
Watch this video demonstrating how to conduct an Adhesion Test.
Unsound Surface Prep
In the case of an unsound surface, the method of removal may vary. It is important to have an
understanding of these methods, their advantages and limitations in order to select the most
appropriate method for the job.
Click on each method to learn more:
•
Hand
•
Mechanical
•
Heat
•
Chemical
Hand Methods
When to use:
Using hand tools to remove unsound paint films is lengthy and tedious. The paint film would have to
be in such poor condition that it is virtually falling off the substrate to warrant this method.
Basic hand tools are easily accessible and may be suitable when other methods are inappropriate,
e.g. when heat and flame may be a fire hazard, when there is no electricity on site, or when chemical
methods are unsuitable.
Tools:
•
Scrapers (Skarsten / universal types)
•
Abrading (course sandpapers)
Page 9 of 26
Mechanical Methods
When to use:
The use of power tools for removing paint coatings is often the most efficient method.
Sanders are most suitable for removing paint from flat surfaces. Moulded and shaped surfaces are
unsuitable due to their awkward profiles.
Tools:
•
Disc sander
•
Orbital sander
•
Belt sander
Disc Sander
The use of a disc sander is a fast and cost effective method of removing paint from a surface.
Example Equipment:
Makita Disc Sander
Procedure:
•
Select a suitable grit pad for the surface.
•
Wear hearing protection muffs, goggles, dust masks and overalls.
•
Switch on the machine and apply to the surface.
•
Hold the sander at an angle of approximately 10-20 degrees to the surface.
•
Move sander along the surface applying pressure to remove coating.
•
Finish off with a fine pad if necessary.
•
Do not use on quality timber or furniture.
•
Do not destroy timber.
Note:
•
Coarse papers (40-60 grit) are best suited for paint removal.
•
Finer papers (100-120 grit) can be used to smooth the bare surface after the paint has been
removed.
Orbital Sander
Orbital sanders although not as efficient as other methods, produce a very smooth finish and are less likely to
damage the surface as a disc sander.
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Example Equipment:
Makita Orbital Sander
Procedure:
•
Select a suitable grit paper.
•
Wear hearing protection muffs, goggles and dust masks.
•
Switch on sander and apply to surface.
•
Keep sander horizontal to surface.
•
Move smoothly over surface with forward and backward strokes applying light pressure on
the sander to grind down the surface.
•
Finish off with a fine paper if necessary.
Note:
•
The orbital sander will leave a fine pattern of circles on the surface.
•
It may be necessary to finish sanding by hand to remove the circle patterns.
Belt Sander
Belt sanders are slower than disc sanders at removing coatings but are capable of producing a much
smoother surface.
Example Equipment:
Hitachi Belt Sander
Procedure:
•
Select a suitable grit belt.
•
Wear hearing protection muffs, goggles, dust masks and overalls.
•
Switch machine on and hold firmly. The machine will ‘run’ across the surface in the
direction of belt rotation.
•
Apply sufficient pressure on sander to remove coating.
•
Move machine smoothly over surface and avoid uneven pressure.
•
Finish off with fine paper if necessary.
•
Sand with the grain, not across it.
•
Ensure the machine is held horizontal to surface at all times.
•
Machine will gouge surface if not used carefully.
Note:
•
Rotation of the belt exerts a great deal of force towards the back of the sander and the
timber being worked.
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•
Timber must be fixed or restrained.
Heat Methods
When to use:
Heat methods are ideal when removing heavily layered coatings. Applied heat causes the coating to
soften and bubble so it can be removed with a scraper. It is efficient and less labour intensive than
hand removal methods.
If used indoors, placement of non-flammable sheeting is recommended. Heat is also not practical
when removing water based coatings as the acrylic becomes a sticky consistency that is difficult to
remove.
Tools:
•
Burning off tools
•
Heat guns (hot air guns)
Burning Off Tools
Burning off is normally carried out using an LP gas appliance. Avoid breathing in smoke and do not use on
days of total fire ban. Some paints may burn furiously once alight, while other coatings may split or soften
with little heat. Handle with extreme care.
Example Equipment:
•
LP gas bottle
•
Shave hooks
•
Flat burning off scraper (long handle)
Procedure:
•
Wear goggles, dust masks and overalls.
•
Hold the gas torch in one hand, turn the gas on and ignite the torch at the end of the nozzle.
The scraper is held in the other hand.
•
Apply heat to the coating by slowly moving the flame around, allowing sufficient time for the
coating to soften.
•
Based on the principle that hot air rises, start from the bottom of the surface and work
upwards. This allows paint above to be softened as you work.
•
Scrape the softened paint with a scraper while coating is still hot/warm. As the coating
cools, it will harden and will require re-burning.
•
When the coating is scraped off, sand down to remove surface roughness prior to priming.
Note:
•
Do not overheat and burn the substrate.
Page 12 of 26
•
Not suitable for timber that will be painted with a clear finish as burn marks may be visible.
Heat Guns (Hot Air Guns)
Hot air guns emit a stream of hot air that can blister and soften paint. They can be used indoors and on
days of total fire ban. As there is no naked flame, they can also be used to remove clear coatings. This
method is slower than the burning off method.
Example Equipment:
Makita Heat Gun
Procedure:
•
Clear the work area.
•
Switch the machine on.
•
Apply heat to the surface, allowing sufficient time to soften the coating.
•
Remove softened coating with a scraper.
•
Sand down to remove any surface roughness.
Note:
•
Do not apply heat to glass.
•
There is no flame, so there is no risk of burning timber.
Chemical Methods
When to use:
Chemical methods are an efficient and clean way of removing paint. Ideal for removing several
layers of paint at a time. Best used on surfaces such as timber where a clear coating will be applied.
Not usually recommended for external use as evaporation causes chemicals to dry before having an
effect on coatings.
Products:
•
Acids and alkalis
•
Paint remover
Acids & Alkalis
Both acid and alkali methods are similar as paint removal is usually carried out in a ‘bath’. For this reason, it
is not common practice for a painter to have all the necessary equipment.
Page 13 of 26
Example:
Hydrochloric acid
Procedure:
•
Wear goggles, respirator, overalls and gloves.
•
Submerge the coated object into the ‘bath’ and allow the chemicals to attack the coating.
•
The time taken to remove the paint coating can vary from two to twenty-four hours.
•
Withdraw the item from the ‘bath’, careful not to splash or touch any chemical.
•
Scrub down to remove paint residue and wash with water to neutralise.
Note:
•
Poor neutralisation may lead to adhesion problems.
•
Acid and alkali methods may cause shrinkage and splitting of timber joints.
•
These methods are not recommended for valuable and quality timber articles.
Paint Remover
Paint remover comes in a paste-like form. Solvents in the paste penetrate and soften the coating. Ideal for
indoor use. As most removers are based on methylene chloride, only use when there is proper ventilation.
Example:
Selleys Kwik Strip paint stripper
Procedure:
•
Always wear protective clothing, rubber gloves and safety glasses. Do not inhale vapours.
•
Protect surfaces adjacent to area being treated.
•
Apply the paint remover with an old brush.
•
Allow to stand for 15 minutes or as recommended by the manufacturer.
•
Scrape off affected paint coatings.
•
Repeat until surface is clean.
•
Wash surface as per manufacturer’s instructions. Poor neutralisation will lead to adhesion
problems.
•
Allow to dry and sand down surface.
•
Dispose of debris safely.
Note:
•
Be careful when opening the can – vapour pressure inside may cause the lid and contents to
‘fly out’.
Page 14 of 26
•
Do not wash in hot water as steam may emit a toxic vapour.
•
If remover comes in contact with skin, wash affected area immediately.
•
Avoid applying in warm breezy conditions as the paste may dry too quickly and not
penetrate the coating.
•
If applied too sparingly, only the top layer of paint will be affected.
Unsound Surface Prep - End
Once an unsound surface has been removed of its coating, it is now ready for the final stages of
preparation.
End of Stage 1: Evaluation
After the first stage of preparation, the surface you’re dealing with should be sound and ready for
Stage 2 of Preparation. Let’s recap what we’ve learnt in Stage 1 to make sure the surface is ready:
New Surface
•
Moisture Test
•
pH Test
Pre-Wallpapered Surface
•
Manual
•
Steam Stripper
Pre-Painted Surface
•
Hand Methods
•
Mechanical Methods
•
Heat Methods
•
Chemical Methods
Stage 2: Cleaning
The second stage of preparation is to wash, abrade, fill and stop the surface so that it’s ready for
painting. Click on each of the sound surface preparation techniques to learn more:
•
Washing
•
Abrading
•
Filling / Stopping
Page 15 of 26
Washing – Introduction
Surfaces in areas such as kitchens, bathrooms and laundries, and those affected by stains will need
to be washed down prior to painting.
Smoke deposits, dirt, soap, grease and fingermarks must be removed, or the following faults may
occur:
•
Slows down or prevents drying of coating
•
Discolouration of coating due to grease, smoke, oil, etc.
•
Poor or lack of coating adhesion
•
Poor quality finish
Washing – Common Types
Material
Advantages
Disadvantages
Sugar soap
•
•
Inexpensive
Etches the surface
•
•
Softens paint if mixture is too strong
Residue left on surface may slow or
prevent drying of subsequent coatings
Washing
soda
•
•
Inexpensive
Does not froth up
•
•
Softens paint if mixed too strong
Difficult to rinse off all traces; residue
may affect drying of subsequent coatings
Detergent
powder
•
Removes grease very
efficiently
•
•
Softens paint if mixed too strong
Expensive and difficult to remove
because of its frothing action
Soap
powder
•
•
Milder than detergent
Does not soften paint
•
•
•
Expensive
Difficult to remove froth and greasy film
Residue may affect drying of subsequent
coatings
Emulsifying
liquids
•
Excellent degreasing
properties, particularly
thick grease and oils
from absorbent
surfaces
•
Expensive
Table 1 - Common types of washing products with separate columns for the product name, advantages and
disadvantages.
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Washing – Procedure
Steps:
1. Mix the detergent solution in a bucket.
2. Use an old grass fibre brush (approx. 150mm) to apply the detergent as some solutions are
harmful to bristles. Sponges are also suitable.
3. Work from bottom to top. If upper surfaces are cleaned first, detergent will run
downwards and may cause streaking of the lower surface.
4. Using a brush, scrub an area of approximately 1m2.
5. Rinse this area with a sponge and clean water before continuing.
Notes:
Always follow manufacturer’s directions, as strong mixtures of detergents may soften paint.
Safety Tips:
•
Due to the corrosive nature of some detergents, do not immerse your hands in washing
solutions.
•
Wear rubber gloves and eye protection.
•
Beware of slip and electrical hazards.
Washing – Solvent Cleaning
Various paint thinners and solvents may also be used for the removal of oil, grease, wax, silicone,
etc., particularly on metal surfaces. These solutions may cause health and fire hazards; therefore,
care must be taken when using these products.
Remember:
•
Do not place or carry solvent wet rags in the pockets of your overalls or clothes.
•
Do not allow solvent rags near food and drink.
•
Never leave used or solvent saturated rags in a confined space as spontaneous combustion
may result.
•
Hang saturated rags to dry or place them in water.
•
Do not allow solvent rags to touch painted surfaces as it may cause blistering.
Examples:
•
Diggers Methylated Spirits
•
Diggers Mineral Turpentine
Page 17 of 26
Washing – Acids & Alkalis
You may also find that acids and alkalis are useful as cleaning, etching and neutralising agents in the
washing process. Acidic surfaces need to be washed and neutralised with a mild alkaline solution,
and vice versa. Many surfaces may be acidic or alkaline due to its nature, treatment or
environmental factors:
Acidic
Alkaline
Various types of timbers contain acids such as
grades of red pine (western red cedar).
Surfaces such as cement, plaster, fibrocement
sheeting, brick, etc. are alkaline in nature.
Some timber saps are slightly acidic and can
react with some paints.
Surfaces may become alkaline in practical use,
e.g. when treated with caustic soda, ammonia,
sugar soap, etc.
Cooking fumes in kitchens may produce
deposits of acid salts and fats.
Highly acidic atmospheres in city and industrial
areas due to the presence of sulphurous fumes
may chemically react with coatings causing
excessive or premature film breakdown
Table 2 - Example scenarios where the surface may be acidic or alkaline.
Acids & Alkalis: Common Trade Types
Alkaline
Acidic
Common Trade Types
Uses
Phosphoric acid
Etching and conversion solutions
Oxalic acid
Timber bleaching agent
Chromic acid
Etching solution
Acetic acid
An etching and neutralising agent
Ammonia
Bleach and neutralising solution on timbers
Caustic soda
Removal and cleaning agent
Lime
Degreasing bleach and ingredient in various substrates
Sugar soap
Cleaning solution
Sodium hypochlorite
(White King, bleaching agent)
Treatment of mould and fungi
Table 3 - List of common trade types of acids and alkalis, with each row showing the type of acid or alkali and its uses.
Abrading – Introduction
An abrasive is a hard material used to smooth rough or irregular surfaces.
Page 18 of 26
Abrading is useful for:
•
Sanding down surfaces until smooth so the coating can adhere to it.
•
Slightly roughening surfaces which are too smooth to provide a ‘key’ or grip for the paint
coating.
Abrading – Methods
Rubbing down, more commonly known as ‘sanding’, are either classified as dry sanding or wet
sanding.
Dry Sanding
Dry sanding is generally for levelling or smoothing surfaces prior to painting. A block of cork or
wood may be used to enable pressure to be applied evenly.
Rubbing with the grain is essential if the timber is to be stained or clear finished, as scratches across
the grain will show when the surface is stained.
Wet Sanding
Wet sanding has several advantages over dry sanding:
•
Total absence of dust
•
The lubricating action of water or spirit lubricant prevents clogging of the abrasive, lessens
the danger of scratching and provides a smoother finish, especially when preparing for acrylic
lacquer finishes.
Abrading – Common Types
•
Silicon Carbide Paper (Wet / Dry)
•
Production Paper
•
Garnet Paper
•
Zinc Stearate (Dry Lube)
•
Wire or Steel Wool
•
Rubbing & Polishing Compounds
Silicon Carbide Paper
(Wet / Dry)
Grades:
120, 180, 220, 280, 320, 400, 600, 800 and 1200. The lower the number, the coarser the paper.
Page 19 of 26
Properties:
Synthetic silicon carbide affixed to a waterproofed backing paper.
When used with a lubricant, dust is eliminated and less chance of paper clogging, enabling a faster
cutting. The lubricant helps prevent scratching. It has superseded the use of pumice stone and
other abrasive powders. It is tough and long lasting if kept unclogged during use.
Usage:
Usually only used where a smoother finish is required. Used with water for abrading all types of prepainted surfaces.
Production Paper
Grades:
40, 60, 80, 100 and 120. The lower the number, the coarser the paper.
Properties:
Synthetic aluminium oxide on paper with a water soluble adhesive. It is available in sheets or in a
roll with paper or cloth back. It is tough and has a very hard cutting edge.
Usage:
Used dry for heavy abrading operations by hand or mechanical sanding tools.
Garnet Paper
Grades:
40, 60, 80 and100, open coated to grade D.
Properties:
This is a natural garnet open coated to grade D paper with a water soluble adhesive. It has a very
sharp cutting edge.
Usage:
Used dry for hand or mechanical abrading of wood that is to be painted or varnished.
Zinc Stearate (Dry Lube)
Grades:
120, 180, 220, 280 and 320.
Properties:
A high quality dry abrasive paper. Contains a dry lubricant to retain the cutting edge. It is
sometimes referred to as ‘open cut paper’.
Page 20 of 26
Usage:
To cut back previously painted surfaces.
Wire or Steel Wool
Grades:
Available in various grades.
Properties:
Formed by shaving thin wire strands from low carbon steel and combining them into balls, rolls or
pads. The strands are sharp but soft and malleable. Abrading is normally done by hand (wearing
protective gloves).
Usage:
•
Ideal for abrading moulded/shaped items where sand paper access may be limited.
•
For degreasing and etching metals and plastics.
•
For scouring timber after stripping with a liquid paint remover.
•
For flatting varnish or lacquered surfaces to produce a matt finish.
Rubbing & Polishing Compounds
Grades:
N/A.
Properties:
Made from an abrasive suspended in a paste. Some abrasives are a mixture of cristobalite and
quartz. The paste may contain products of oil, e.g. kerosene, to help in the cutting action.
Rubbing and polishing can be done either by hand using a soft cloth or using a buffing machine and
pad.
Usage:
Used for rubbing and polishing synthetic and nitro cellulose finishes, but can be used to etch surfaces
that sand papers may scratch.
Example:
K+H Buff N Shine Cutting Compound
Filling/Stopping – Introduction
When preparing surfaces, it is necessary to fill repaired defects and indentations so that they are not
seen in the finished job. This is called filling and stopping.
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Filling is the process of filling slight surface imperfections by applying a smooth paste (filler) with a
filling knife or blade.
Stopping is the process of levelling holes or cavities with a material that dries with minimum
shrinkage.
Filling – Filling Materials
Filling materials can be categorised as either:
•
Water mixed cellulose fillers, or
•
Ready mixed oil based fillers.
Filler
Uses / Properties
Plaster/cellulose based
(‘polyfilla’ type)
•
•
•
•
Used on plaster and for filling grain in timber
Good adhesion
Slight shrinkage on drying
Absorbent when dry
Plaster/vinyl based
(‘instant polyfilla’ type)
•
•
•
•
Used on internal surfaces
Supplied ready mixed
Very smooth paste
Shrinks on drying
Cement/vinyl based
(‘exterior polyfilla’ type)
•
•
•
Used for external surfaces
Excellent adhesion and water resistant
Brittle and difficult to abrade
Synthetic emulsion based grain
fillers
(‘fine surface polyfilla’ type)
•
•
•
•
•
Used for internal and external surfaces
Supplied ready mixed
Very smooth paste
Can be worked to a fine feather edge
Quick setting
Table 4 - Different types of fillers and their uses and/or properties.
Example Images:
•
Polyfilla Professional Interior Powder Filler
•
Polyfilla Professional F6 Deep Filler
Filling – Acrylic Fillers
Properties:
Flexible acrylic filler is available in white, brown and grey colours.
Usage:
•
Can be used for filling most building materials both internally and externally.
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•
Filling cracks around door and window frames, cornices and skirting.
•
Blade filling small joints, cracks, etc.
Procedure:
•
Acrylic fillers must be smoothed off immediately upon use as a skin forms in 20 minutes
and fully sets in 7 days (setting time alters with weather conditions).
•
Once dry, the filler cannot be sanded.
•
For deep cracks, do not fill more than 10mm deep – allow to dry and repeat procedure.
Notes:
•
Do not leave these fillers exposed outside as they will re-crack. Painting over is
recommended.
•
Do not use if rain is imminent.
Example:
Selleys No More Gaps – Multipurpose Gap Filler Gun
Stopping – Stopping Materials
A stopper is a flexible material that dries with minimum shrinkage and useful for treating large holes
and cracks.
Stopper
Linseed oil putty
Uses / Properties
•
•
•
Commonly used on wood for stopping holes and
fixing glass in place.
Less expensive than hard stopper
Becomes brittle with age
Plaster
•
•
•
•
Stopper for gypsum and lime plasters
Quick setting and drying
Rake out and undercut for good adhesion
For deep holes, sand is added to the plaster to reduce
shrinkage and cracking
Sand and cement mix
•
•
Four parts of sand to one cement (4:1)
Used for deep holes in plaster and making good
external rendering and brickwork
Mastic (acrylic gap sealer)
•
•
Very flexible material based on oil, latex or resin
Mainly used around external doors and window
frames
Usually applied with a caulking gun
•
Cellulose stopper
•
•
•
Used extensively in the vehicle refinishing industry
under nitro cellulose finish
Quick drying
No shrinkage
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Stopper
Uses / Properties
Plastic wood
•
•
•
•
•
Mixture of wood flour and resin
Used under clear wood finishes
Ready mixed or two-pack varieties
Quick setting
Expensive
Tinted stopper
•
•
•
Water borne
Used under clear wood finishes
Available in a variety of colours to match stained wood
Waterproof sealant
•
•
•
•
Very flexible – based on latex or silicone resin
Waterproof
Tinted
Filling cracks around baths and basins
Table 5 - List of stopping materials and their uses and/or properties.
Examples:
•
Polyfilla Professional Putty
•
Selleys PlastiBond Builder
Stopping – Procedure
Equipment:
•
Filling blade
•
Putty knife
•
Filling knife
•
Water
•
Brush pallet for mixing filler
Notes:
•
Make sure your equipment is clean.
•
To avoid unnecessary sanding, remove excess stopping material from the surface before
setting takes place.
Procedure:
•
Dust or rake out the crack or hole before filling to ensure good adhesion.
•
Prepare stopping material to manufacturer’s instructions.
•
To avoid wastage, mix only sufficient filler that can be used within setting time.
•
Stop up large cracks or holes first. They may require a second coat.
•
Work from top to bottom – ceiling, walls and woodwork.
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•
To minimise shrinkage of stopping material on solid plaster surfaces, wet the hole or crack
with water before you apply the stopping material.
Conclusion
Main Painter: I’m starting to understand why preparation is so important now.
Helper Painter: Remember - with the right preparation methods and tools, you can be assured that
you’re doing a professional job that will satisfy customers.
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).
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 2: Preparation (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 of ‘Dulux’, ‘Selleys’ and/or ‘Poly’ products were used with permission from DuluxGroup.
All images of ‘Pascoes’ products were used with permission from Pascoes Pty Ltd.
All images of ‘Diggers’ products were used with permission from Recochem Inc.
All images of ‘K&H’ products were used with permission from 3M.
All images of ‘Makita’ products were used with permission from Makita.
All images of ‘Hitachi’ products were used with permission from Hitachi Power Tools Australia.
Disclaimer: All images of branded products were used for illustrative purposes only. Please note
that other brands are available for purchase in your line of work.
All other images used in this resource are owned by Polytechnic West. © Polytechnic West 2013
Information within this resource was current at 2013.
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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.
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