How to Remove Old Paint

There are two main methods of removing old paint – with heat from a blowlamp or gun or by using a chemical paint stripper. Both methods work by softening the paint film, making it blister and lift, so that it can be removed with a stripping knifeor shave hook. In terms of time and trouble, there is not much to choose between the two methods – both are time-consuming and messy. And both methods can be dangerous.

You may also remove old paintwork with some sort of abrasive, but this is hard work (even if you use power tools) and creates a lot of dust. You are most likely to need to use abrasive papers for finishing off a surface just before you paint it – after using a chemical paint stripper, say – or for rubbing down between coats of paint to provide a key for the next coat.

Remove Old Paint

Using heat

A blowlamp is a flame gun which burns liquefied petroleum gas. Using a blowlamp is the most economical method of stripping large areas of oil-based paint (normal gloss paints, say). Other types of paint such as emulsion or cellulose (often found on ears) cannot be removed successfully by flame, and a blowlamp is not suitable for stripping paint over materials, such as plastic, which would be affected by the heat.

A blowlamp can remove paint fairly rapidly and is particularly suitable for flat areas, but to avoid burning the surface under the paint the flame must be moved continuously over the paintwork. Edges and mouldings are difficult to strip with a blowlamp and are likely to be burnt. Areas adjacent to glass are also difficult to strip without the glass being cracked by the flame. And you should not use a blowlamp when you want to leave wood with its natural appearance after you have stripped it. In all three of the above situations the best way to strip paint is with a chemical stripper. Do not use a blowlamp outside when it is windy in these conditions the flame cannot be controlled effectively.

If you have a lot of paint stripping to do, you should choose a lamp which is comfortable to hold and economical to use. Lamps with broad flame burners do not seem to work consistently better than those without them. A blowtorch is lighter and easier to hold but has to be used near its cylinder.

Gas blowlamps use either butane or propane. You attach a cartridge or cylinder to the burner, open a valve to let out a stream of gas and burn it. Gas blowlamps generally work off cartridges; gas blowtorches (see picture) work off cylinders at the full pressure of the gas inside the cylinder – few have pressure-reducing regulators. The pressure inside the lamp depends on temperature as it gets colder the blowlamp becomes less effective. Butane lamps will not work below 0¡ãC but propane ones keep going down to ¡ª 40¡ãC. The pressure inside the lamp docs not depend on how much gas is left. Both gases are more dense than air, so gas leaks flow along surfaces and collect in hollows. Never tilt a gas lamp in use until it has been lit for about five minutes. If you do the lamp may produce a huge flame and drip burning liquid.

Hot-air guns are like large hairdriers (though should never be used as one!): air is blown over an electrically heated element and the hot air softens the paint so it can be scraped off. They have the advantage over blowlamps in that they do not scorch wood and. if used with a shield, can be safely used near glass. Many have optional spreader nozzles, useful for stripping large fiat items, and concentrator nozzles, useful for narrow ledges and crevices or corners.

The main disadvantage of an electrical hot-air gun is that you are limited by the flex (most uses will require an extension lead) which can also get in the way.

Using a blowlamp or gun

lust prepare the area by placing a non-llammablc sheet underneath to catch scrapings (not always necessary outside) and remove extraneous flammable things from the vicinity of the flame. Before starling to strip, put on tough gloves -burning paint could fall on to your hands and cause a nasty burn.

Remove Old Paint

When using a blowlamp, allow it to warm up for a few minutes before use. Hold the blowlamp in one hand and a shave hook in the other. Play the flame (which is invisible in bright sunlight) over the painl from a distance of approximately 150mm. As the paint begins to bubble, pull it off with the scraper. Two passes will probably be required to leave the surface fairly clean. Slight ridges and mottling of dried paint can be abraded off once the surface is cool. With a hot-air gun, use a flat scraper.

Never use a blowlamp for stripping old lead-pigmented paint (assume all very old paint is this type) unless the area is well ventilated. Do not use a blowlamp to strip paint on softwood fascia or soffit boards – old birds’ nests are very flammable and if one catches alight it could result in a major roof fire. Never use a blowlamp near a thatched roof.

If using an extension lead with a hot-air gun, it is vital that this has the rating for the power of the gun (always more than 5 amps) and that it is fully unwound to avoid overheating of the extension flex.

Filed Under: Home & Maintenance


About the Author: Jason Prickett loves to write about home maintenance and stuff you can do yourself instead of hiring any professional. His step by step guides will assist you in completing your home maintenance tasks.

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