Painting and Finishing Internal Bifold Doors

Our internal bifold doors come in a range of finishes with the option to purchase already painted and ready to hang. Some customers prefer however to purchase their internal bifold doors unfinished so they can paint them at home to match existing doors within their interior.

Thanks to their complex folding nature (not to mention their considerable size) internal bifold doors are a little trickier to paint and finish. But if you follow the right procedure, the task is quite straightforward.

In this article, we’ll talk you through everything that’s involved in painting and finishing a set of internal bifold doors – whether it’s a set you’ve just bought or one that’s been in your home for years and needs a little care and attention.

Prefinished, Unfinished and Primed Internal Bifold Doors: What Do They Mean?

Let’s start by clearing up a few terms. When shopping for internal bifold doors (or timber doors of any sort), you might have heard the terms ‘prefinished’, ‘unfinished’ or ‘primed’ bandied about. But what exactly do they mean?

Prefinished Doors

A prefinished door has a layer of finish applied at factory level. All the homeowner needs to do is get it installed, and it’s ready to go. Factory-level finishes tend to be a great deal more consistent, resilient and long-lasting than the ones you might apply at home, and so this is a fantastic way of saving time and effort – provided, of course, that you’re willing to sacrifice flexibility.

Unfinished Doors

An unfinished door, as you might expect, comes with no finish whatsoever applied as standard. It will, therefore, give you the freedom to apply whatever finish you like. If you’re looking to minimise costs, a set of unfinished bifold doors might appeal – you’ll make extra work for yourself, but you’ll be able to paint the doors to match your windows, furniture or decor.

Primed Doors

Primed doors strike a compromise between the two types of door we’ve mentioned. They’re ideal for those looking to paint their doors a specific colour. A white-primed bifold door will arrive with a coat of primer that’s been applied at factory level, but the topmost coats of paint are left for the homeowner to apply. If you’re going to be painting your door any colour other than black, then pre-priming is a great way to save yourself time and money.

What Type of Paint for Internal Bifold Doors

If you’re thinking of painting your bifold doors, you’ll also need to think about what sort of effect you’re going to opt for. Glossy paints have a shinier appearance, and they’ll more capably resist dirt and stains. Satin paints offer more of a matte-style effect (though they aren’t quite as understated as the stuff you put on your walls). Given that doors are expected to absorb more muck and fingerprints, it should come as no surprise that gloss finishes are more popular.

How to Paint Primed Internal Bifold Doors

Painting a pre-primed bifold is fairly straightforward. Let’s run through the required process.


First, we need to cover the ground with a sizeable cloth sheet. You can then put two sawhorses into place for each panel you’re going to be painting in one go. Laying your panels flat will minimise the chance of paint runs. You’ll need to remove the hardware from the door – it’ll make life awkward, particularly if you’re looking to lay each panel flat on the floor. Ideally, it’s best to disassemble the entire thing – that way you’ll be able to easily access the edges of each panel.


If the primer is already applied, then you won’t have any further cleaning or sanding to do. Just give the door a quick wipe with an almost-dry cloth and start painting. Start from the top of each panel and apply the paint in long, thin strokes. It’s better to apply multiple thin layers than it is a single thick one. Work your way from the centre and finish with the edges. If you’re painting the door for the first time, paint underneath where the locks and hinges will go. This will create a complete seal around the entire door and ensure that the moisture level on the inside will remain consistent.

It’s essential that you allow each coat dry before applying the next – you might wish to leave each overnight. Since you’re going to be painting two sides of each panel, this might add a considerable amount of time to the process, but it’s the only way to achieve consistent results. Keep applying layers until you’re happy with the way the door looks but be sure to check that the edges of your doors aren’t given so much extra paint that they end up touching one another. This possibility can be avoided by regular wet-sanding; after each coat is dried, sand and clean the door before applying the next.

How to Spray-Paint Bifold Doors

If you have the necessary equipment, then you might be tempted to use a sprayer rather than a brush to apply your paint. To be able to handle gloss paint of the sort that looks good on doors, your sprayer will need to be heavy-duty. What’s more, you’ll need to work in a well-ventilated area and ensure that any hardware is removed, and any glazing is suitably masked. It’s also worth considering that spraying is wasteful – a significant portion of the paint will vaporise before it has a chance to settle onto the surface of the door.

Spray-painting will ensure that the layer of paint is nice and thin. This is especially important in the case of bi-folds, whose edges must come into close contact with one another without the risk of rubbing and touching.

How to Paint Wooden Internal Bifold Doors

If your doors lack a coat of primer, then you’ll need to apply one yourself before moving onto top coats of paint. This is also true if you’re refurbishing an older set of bifold doors. The process is broadly similar to the one we’ve outlined above, except you’ll need to spend a little extra time on preparation.

Sanding Internal Bifold Doors

You’ll need to apply your primer to a smooth, clean surface that’s free from nicks and scratches. If your door is new, this might not be a problem; if it’s old, you’ll need to fill in any gaps with wood filler. In either case, give the door a once-over with fine sandpaper, eliminating any visible blemishes. Then use a damp cloth to clean away any sawdust residue.

If you don’t clean away all of the dust, you’ll end up trapping it beneath the primer, which will cause an unsightly bobbling that’s especially visible with gloss. You’ll need to also ensure that the surface of the wood has entirely dried before you apply any paint. Fail to do this, and you risk trapping moisture inside the door, which can lead to rot and other problems.

In the case of an internal door, this isn’t such a considerable problem, as you won’t need to worry about rainwater interrupting the drying process, and you’ll be able to take as long as you need for the door to dry.

Priming Internal Bifold Doors

Apply the primer using a wide brush, or, if the door is flat enough, with a roller. In most cases, you’ll just need a single coat of primer. Apply it to the front, wait for it to dry, and then repeat the process on the rear. You might need to lightly sand the primer for maximum smoothness.

From this point, you can move on to painting the door in exactly the manner we’ve described above.

It’s worth noting that our pre-finished doors come with a lengthy guarantee, offered in accordance with EN927/1-7. This assumes that the door is well looked-after during its lifespan. If the finish is allowed to degrade to the point that moisture can get into the timber, then the door will deteriorate well before its time. Check your doors every six months or so for signs of degradation. If a given part of the finish appears to be wearing away, then repair it – and check that whatever has caused the deterioration is prevented from doing so in future.


If your bifold doors are to look their best and last for as long as possible, then they’ll need to be finished in the right way. This means taking the time to adequately sand and clean your door before adding your coats of primer and paint, taking the time between each for thorough drying. This might mean setting aside an entire weekend for thorough drying – or perhaps even longer. The results, however, are sure to be more than worth it. If you’re looking to achieve a particular colour, then you’ll have no choice but to go down this road.

If, on the other hand, you’d prefer to get your doors installed as soon as possible, you might prefer to go for a pre-finished door. This option will save you the trouble of painting the doors when they arrive.