Depending on whether you’re painting a cement or timber wall, you’ll need to tackle the job in particular ways.
Cement Based Walls (brick, fibrolite, concrete, masonry, stucco etc)
Cleaning & Preparing
PAL® Handy Tip: Dust from old lead or chromate based paint can be very dangerous! Visit the OSH site for advice on dealing with such paint.
New Concrete
New concrete surfaces need to cure for at least 28 days before painting. During this time, wipe away salt and lime build-up.
After 28 days, use a wire brush to clean the surface. Then rub the surface down to wipe off any loose sand.
Fill all cracks, gaps and holes with exterior filler.
Sand it smooth and dust off.
Apply a suitable primer if the surface is powdery or porous and to lock in the lime. Ask your paint store sales person for advice.
Old Concrete
Your first step is to water blast the surface. The aim is to remove any loose and flaky paint, and to wash off any mould and dirt. Mix an anti-fungal solution into the water
Fill all cracks, gaps and holes with exterior filler
Sand it smooth and dust off
Apply a suitable primer if the surface is powdery or porous and to lock in the lime. Ask your paint store sales person for advice
Be sure to dampen the surface with a hose before you start painting. The moisture will make it easier to paint.
Painting
Type of paint
The best paint to use on concrete based exterior walls is a water-based low sheen acrylic. It’s easy to apply, good on porous surfaces, rapid drying and easy to clean up in water.
Best applicators for the job
For painting cement based walls we recommend using a good quality, big roller. Try a PAL® Roller No.3 (180mm or 230mm) for water-based paint, to give you quick coverage and a nice finish
If you prefer to use a brush, choose a large one, see our section “How to select a brush” for assistance
The first thing to do is to wash the timber surface down with a warm water and sugar soap solution. Dirt and grease tend to build up around door handles and window catches especially. So be sure to give these areas a really good scrub.
If the paintwork is glossy, you might want to rub the gloss down to remove imperfections and create a slightly rougher surface for the new paint to stick properly. Rub down with 200 grit wet and dry abrasive paper dipped in water.
Previously Painted Timber In Good Condition
If the timber has been previously painted, check to see if the paint work is in good condition. If it is, just rub it down with a rag dipped in methylated spirits. Then rub down gloss with 200 grit paper.
This is all the stripping you’ll need to do before filling and then priming.
Always prime previously painted timber with an oil-based primer unless you have totally stripped the timber bare.
Previously Painted Timber In Poor Condition
Harder stripping will be needed if the previous paintwork is in poor condition (flaking, cracked, peeling, etc) or if the previous colour is much darker than the new colour.
Rub down gloss.
Replace or repair any rotted timber.
Prime bare patches of wood.
Fill gaps, cracks and nail holes with exterior wood filler (flexible filler).
Remove any loose putty on windows, and replace with new putty.
Always prime previously painted timber with an oil-based primer unless you have totally stripped the timber bare.
Cleaning & Preparing Specifics for Different Types of Timber
Bare timber
If bare timber has been exposed to the elements for more than a month, you’ll need to sand it back before you paint it
Replace all rotten and decayed timber
All new timber should be primed first. Only THEN should you fill gaps, cracks and holes with exterior wood filler (flexible filler)
Sand smooth and dust down
Then prime. Always use an acrylic primer on new timber.
Weatherboards
A lot of people make the mistake of water blasting weatherboards, and end up with a whole lot of water inside their walls! If the previous paintwork is in good condition, it may just need a good wash down with a sugar soap/water solution and then a fine sand.
If paint comes of easily with light scrapes, you’ll need to strip it back to a smooth surface before painting.
Scrape off, or wire brush away all peeling paint. You can use a heat gun on large areas to soften the paint if the previous paint is water-based. Then you’ll just need to scrape off softened paint with a stripping knife. Don’t use a heat gun around windows though. They might crack the glass. Use a chemical stripper instead.
If the previous paint is oil-based, use an LPG fuelled blow torch to soften the paint, or just sand by hand or with a machine sander.
Spot prime any bare timber.
Remember that previously painted timber must be primed with an oil-based primer unless you have totally stripped the timber bare.
Wood Surfaces (Cedar etc.)
Apply a moss and mould killer to the timber, and leave on for up to 2 days. You may need to repeat this process if the moss or mould is really stubborn
Be sure to thoroughly wash the timber off to get rid of residue
We recommend also using a deck cleaner and brightener that will take the grey out of weathered wood. Try Flood® Dekswood, available in 1L and 4L.
Then sand. When sanding timber, sand WITH the grain. The aim is to get rid of small imperfections and loose fibres from the surface. Loose fibres are likely if the timber has been exposed to the elements for more than a week
Dust the timber off.
Painting
Type Of Paint
For weatherboard use a gloss acrylic
For other timber walls you can use a low-sheen pigmented paint or a semi-transparent penetrating oil stain
For weatherboards, and when using any kind of water-based paint on timber, use one of PAL®’s Masterflow® brushes (available in three price ranges to suit varying budgets). And try a Speed brush handle and pad (125mm/175mm available).
For painting a cedar type wall we recommend using rollers. To select the correct roller use the PAL® Roller System to match to the paint you have chosen.
Handy Tips
Always sand and prime timber on the same day. That way you prevent the risk of any moisture getting in and messing with your paint work.
Make sure you have a hose handy if you’re softening oil-based paint with a blowtorch. This process for removing paint can be a very real fire hazard, especially if your torch catches any rot, rubbish, nests or building paper popping out of the wall!.
When painting weatherboard, start from the top. Paint the lap first and then the face. Try to paint to natural breaks if possible.
