Painting Caulk: A Professional Guide

Caulk is a decorator’s best, and sometimes worst, friend. Whilst caulk is an important tool to deal with issues such as hairline cracks and filling the gaps between doors, skirting boards, and windows, painting caulk can cause all sorts of problems.

If you’re currently redecorating your home, you might be tempted to paint unsightly caulk but before you do, read our professional guide to ensure you don’t encounter any issues.

What is Decorator’s Caulk?

Decorator’s caulk is a waterproof and flexible filler designed for use on small cracks and gaps in between window edges, door frames, and skirting boards and is sometimes used as a preventative measure along the edges of walls and ceilings to stop any cracks from appearing.

Once fully dried, caulk takes on a rubbery texture and can expand and contract with the natural movements of the surface it’s applied to.

Can You Paint Over Caulk?

If you follow the correct process it is entirely possible to paint over caulk without encountering any issues. Many variables can impact painting caulk without any problems including the type of caulk, how thick the paint is, and how long you allow the caulk and paint to dry between coats.

Problems to Be Aware of Before Painting Caulk

An example of paint that has cracked after being applied to caulk.

As mentioned above, painting caulk can turn into a nightmare if you don’t follow the correct process. The most common problem encountered by DIYers and professionals alike is cracking and crazing.

Problem 1: Cracking and Crazing

Cracking (or crazing) typically occurs when the caulk hasn’t fully dried yet.

As decorator’s caulk dries, it expands and contracts, and if you apply a paint coating on top of it, the paint will struggle to keep pace with the caulk during this expansion and contraction.

The result is that as the paint dries, it will separate, resulting in a finish that looks cracked. This is especially problematic if you’re using hard-drying paint such as oil-based paint.

How to fix cracking and crazing

Unfortunately, the only way to fix cracking and crazing is by removing the defective coating and caulk.

After removing the paint and caulk, follow the guide as shown further down in this article.

Problem 2: Flashing

Some people also encounter a defect known as flashing after painting over caulk. Flashing is what looks like shiny patches and are easily identifiable. Unfortunately flashing is unpredictable so there’s not much you can do before you encounter this problem.

How to fix flashing

The best thing you can do is to prime the area that is flashing before applying your top coats. I would recommend a coat of Zinsser Coverstain on the problematic area and allowing it to fully dry before applying your top coats.

How to Paint Caulk (Like a Professional)

Step 1: Source an appropriate caulk

One of the most important steps in painting caulk like a professional is sourcing some professional standard caulk. Cheap caulk is cheap for a reason and is the type of caulk more likely to crack and craze.

There are a few caulks on the market that I and many other professionals swear by – one of which I will recommend a bit later in this article.

Step 2: DON’T sand it down

Caulk is not made for abrading so unlike other surfaces, avoid sanding it down when you’re prepping.

Step 3: Allow the caulk to dry

It’s essential that you give the caulk enough time to fully cure before painting over it. As mentioned above, if the caulk is still drying when you apply your top coats, the paint is going to crack.

Bear in mind environmental conditions such as how cold or hot the room is. If the caulk is drying at a low temperature, it’s going to take longer than what the manufacturer suggests. If in doubt, just give it some more time.

Step 4: Apply your first top coat

Once the caulk has fully cured, you can apply your first top coat.

Top tip: if your emulsion is on the thicker side, it’s worth thinning it down 10% as thick emulsion can have a tendency to take longer to dry and thus craze.

Step 5: Allow the first coat to dry

Like the caulk, make sure the first coat has fully dried before applying your next one.

Step 6: Apply any additional top coats

Repeat the steps above until you’re happy with the final finish.

Best Caulk to Paint Over

Caulk is a relatively inexpensive material to source which has led to me trying countless brands over the years. The best, by far, that I’ve used is HB42. HB42 is incredibly reliable and I’ve yet to have an issue with it.

Other brands I’ve tried have always popped up with the occasional problem such as crazing or causing discolouration of the paint applied to it but HB42 seems to be immune to these issues.

My theory is that because it’s so quick drying (about an hour) you’ll never have problems during the drying phase if you leave it overnight (which is what I tend to do with caulk).

Furthermore, it’s very easy to use and smooth over and can even deal with larger cracks without shrinking (although I still recommend using a filler for large and deep cracks!)

Best Paint to Paint Over Caulk With

Another important factor in determining how you avoid issues with caulk when painting over it is the paint you use. I would recommend avoiding contract paints at all costs when painting caulk. In my experience, contract paints frequently crack when applied to caulk so you’re essentially wasting your time by using them on caulk unless you seal the caulk first.

If you want to ensure your paint doesn’t crack or craze then I would recommend using any durable paint. There are a few on the market I prefer to use including Dulux’s Diamond Matt and Johnstone’s Acrylic Durable Matt. Dulux’s flat matt looks a bit better whilst Johnstone’s durable is longer-lasting. With that in mind, take your pick!

Frequently Asked Questions

Are You Supposed to Paint Caulk?

Whether you paint caulk or not is entirely your choice. Some people like to keep the caulk visible if it’s been smoothed over properly and has sharp lines as it can differentiate between wall and ceiling. On the other hand, some people prefer to get rid of the white lines and therefore paint over caulk.

Can You Paint Caulk Straight Away?

No, you can’t paint caulk straight away. You will need to wait for the caulk to fully dry before painting over it otherwise you open yourself up to issues such as cracking and crazing.

What Kind of Paint Will Stick to Caulk?

Any paint will stick to caulk however I would recommend using a durable paint product as it typically has more adhesion. If painting an emulsion on caulk, you can thin it down slightly to give it a better chance of adhering to it.

How Do You Get Paint to Stick to Caulk?

Paint will stick to caulk without priming but if your paint isn’t sticking properly it might be worth using a gripping primer such as Dulux Super Grip Primer.

Do You Need to Prime Caulk Before Painting?

It’s not necessary to prime caulk before painting but some professional decorators will prime to make it certain that they don’t encounter any problems.

Can You Paint Over Cracked Caulk?

Whilst you can paint over cracked caulk, the appearance of cracks on the caulk suggests that it has failed. Therefore, it’s better to dig out the caulk and replace it with a new layer.