Removing old layers of paint: when is it necessary?

Is the paint flaking off your window frames, is there a thick crust on your front door, or are you unsure whether an old layer still adheres properly? Then the question soon arises whether everything has to come off before repainting. In this article you will read when removal is really necessary, which methods are available, what needs extra care in older Amsterdam buildings and when you are better off leaving it to a professional painter.

1. Not every layer has to come off

Many people assume that a good paint job starts with stripping everything back to bare wood. In practice that is rarely needed. A coat of paint that still adheres well, is even and shows no cracks is actually an excellent base: it is degreased, lightly sanded and then painted over. Removing healthy layers anyway takes away protection and leaves the wood needlessly exposed to moisture.

Removal only makes sense when the existing layer is itself the problem. Think of paint that comes away in flakes, a thick crust built up over decades of repainting in which the detail of the mouldings has disappeared, or layers so badly cracked that water creeps in behind them. In Amsterdam buildings with a long history you come across this regularly, especially on street-facing window frames and doors that have been given a new coat many times over.

2. Signs that a layer needs removing

Whether a layer has to go is usually something you can see and feel for yourself. Look out for these signs in particular:

• Paint that lifts in flakes or blisters when you run a filling knife along it.
• A crazed pattern with deep cracks running right down to the wood.
• Bubbles or blistering, often a sign that there is moisture beneath the paint.
• Mouldings and rebates painted up so heavily that windows and doors stick.

If you are unsure about adhesion, a simple tape test gives you something to go on: score a small grid into the paint, press some strong tape firmly over it and pull it off sharply. If a lot of paint comes away with it, the surface is not sound enough to build on. More pitfalls that crop up during this kind of preparation are covered in common painting mistakes.

3. Scraping, heat stripping or chemical stripper

There are three common ways of removing paint, each with its own use. Scraping and sanding work well for loose patches and thin layers. A heat gun softens the paint so you can lift it off with a scraper; that is effective on thick layers of exterior paintwork, but calls for care near glass, sealant and dry timber. Chemical stripper dissolves the paint and is useful on fine mouldings where a scraper cannot reach.

Whichever method is used, the next steps are the same: clean the surface thoroughly, neutralise any stripper residue, let it dry and only then apply primer. How to tackle that next stage properly is explained in the article on primer and surface preparation. A practical order for the whole preparation process can be found in the checklist for preparing paintwork.

4. Older buildings and lead paint

In homes built a long time ago, the bottom layers of paint may contain lead. That used to be common in paint for woodwork. As long as those layers sit beneath a sound top coat, there is little to worry about. Once sanding or burning begins, however, dust or fumes are released that you do not want to breathe in and that should not end up in your home or garden.

That is why, on buildings like these, the work is done by wet sanding or with chemical stripper, the surroundings are covered and the waste is disposed of properly. With canal houses and other characterful buildings, there is the added consideration that original details must be preserved. You can read more about that in painting a listed building. In Amsterdam's historic centre this extra care is the rule rather than the exception.

5. Doing it yourself or hiring a painter

Scraping a few loose spots on a garden gate is something you can easily do yourself. With complete window frames, a front door with a lot of moulding or all the exterior woodwork around the house, removing old layers quickly becomes the biggest part of the job. You see that reflected in the price too: the amount of preparation largely determines what exterior painting costs.

During the free consultation our painter assesses which layers can stay and which have to go, so you do not pay for work that is not needed. The quote then sets out exactly what preparation will be carried out. If you would like to know what is going on with your window frames or doors, feel free to send a few photos through the quote form, so he has a first impression in advance.

In practice this topic belongs with exterior painting and wood rot and window frame repair. There you can read about the approach and the options, or request a free, no-obligation quote straight away.

Further reading: What does interior painting cost?, What does commercial painting cost?, What does wood rot repair on frames cost?.

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