Painting caulk: 6 practical pointers for the perfect finish

Close up of a paintbrush cutting in against a window frame
(Image credit: Getty Images)

Painting caulk is all about perfecting your technique – as well as making sure you are using the correct sealant before you start.

While similar in appearance and finish, silicone is definitely not designed to be painted while the decorators caulk, sometimes known as 'painters' caulk', is. Both sealant and decorators caulk are flexible sealants however, so make sure you are using the right product before you start caulking.

The great thing about decorator's caulk is that it will give you more flexibility when fitting any built-in woodwork. Using it to fill in any gaps and then painting it afterwards will leave you with a smooth finish and colour match to the surrounding areas.

Here we answer a host of common questions on how to paint caulk to get a seamless, professional finish. 

How do I tackle painting caulk?

When it comes to painting caulk you can use the same method as you usually use to cut in when painting. So as long as you know how to cut in paint you can apply this technique to painting around windows, painting around doors and painting skirting boards. All you need to make sure of is that the caulk is dry and clean from dust and debris. 

For those who are terrible at cutting in, you can of course also use painter's tape, but this comes with a massive health warning. Even using the best quality painter's tape can and probably will take off some of the paint underneath, leaving you with little bald patches that you will need to painstakingly go over afterwards. This is almost certainly true if using tape over the top of any newly-painted areas. So basically, if you can, do try to perfect your freehand cutting in technique where possible. And invest in a decent cutting in paint brush to do it with.

Caulk isn’t just used for sealing around these areas, it is also used to seal the edges of cornices and coving. So it if painting a ceiling or painting a wall you simply need to approach the job in the same way as you would any standard paint project. 

How long does caulk take to dry? 

This is a very similar question to how long does silicone take to dry as both work in very similar ways. So it's worth noting that the same drying times can be applied to decorators caulk. 

A standard decorators or painters caulk will be touch dry within 10-15 minutes. This is how long you have to work – or tool – the caulk before it starts to set. Once the caulk starts to set you will not be able to shape it and will need to replace it and start again.

Typically, the caulk will be touch dry within an hour, meaning dust and debris won’t stick to the surface. Give it another couple of hours before you think about applying any paint. Ideally you want to leave the caulk for 24 hours to allow it to fully cure. 

Why does paint crack on caulk? 

There can be a variety of reasons why paint cracks over caulk. It can be the paint and it can be the caulk. Water-based paints like emulsion are typically where the problem occurs and this is more to do with the paint than the caulk.

A good example of this is along the top of skirting boards, around the architrave on doors and windows, where the emulsion meets the paint work. It also occurs where coving has been caulked and painted over with emulsion. Especially when the caulk and paint haven't been allowed to dry properly.

However, to make sure the problem is not the caulk, do not apply too much caulk when sealing skirting boards, doors, windows etc. A thin bead will dry quicker and ultimately will cure quicker. Leave your caulk for at least 24 hours before painting. 

If you have an area where you have too much caulk – or silicone sealant – you should think about removing silicone or caulk and reapplying.

If using an emulsion one option to help cure the cracking is to apply an oil-based primer or undercut over the caulk and leave to fully dry before you apply the emulsion.  

Can I leave caulk unpainted? 

Yes you can but it may attract more dust and can yellow over time.

Decorators or painters caulk is a flexible waterproof filler that is used to fill small gaps. Typically is used for caulking skirting boards, doors and windows and comes in white. If you are applying the caulk to an area where the walls, windows, doors and trim are going to be white then you can leave the caulk as is. That said, you may find the finish not quite as seamless as a crisp layer of paint.

Obviously, if you decide to change the colours of the surrounding walls or woodwork you always have the choice to paint over the caulk.

Can I paint over silicone caulk? 

Silicone sealant isn’t designed to be painted over. Typically, a silicone sealant will be used for siliconing a shower or bath and matches the sanitaryware which is often white. It's also a popular choice for kitchens where a waterproof sealant is needed i.e around sinks.

If white isn’t the colour, you can create a colour match with a coloured silicone sealant. There is plenty of colour choice available, but expect to pay around twice the price you would for a cartridge of white silicone.  

You can use decorators caulk  as an alternative as it is also waterproof, but it should only be used in areas that are subject to occasional water rather than areas likely to be saturated with water like in a shower or around a bathtub.

Should caulk be done before or after painting? 

Unless you are having a complete refurb where you are plastering walls and installing new doors, windows and architrave, then you will almost always be caulking over existing paint. To make sure the caulk adheres as best as possible, clean the existing paintwork with sugar soap and rub down if possible.

If you are adding caulk to new wooden skirting boards you want to make sure that there are primed or undercoated first before you apply the caulk.

Steve Jenkins

Steve is Homebuilding & Renovating's DIY content editor, and has been a writer and editor for two decades. He is an avid DIYer with over 20 years of experience in transforming and renovating homes. He specialises in painting and decorating, but has strong all-round building skills, having previously worked in the industry for 10 years.