Are you wondering if it’s okay to paint caulk? Silicone caulk is often used to seal gaps, cracks or joints between stationary components in a building. It sometimes happens that you need to paint over this caulk and you cannot get a good finish because the paint keeps running away from the sealant.
But how might you actually paint over this caulk?
Let’s take a closer look at everything you need to know.
Can You Paint Over Silicone Caulk?
You cannot paint 100% silicone sealant because silicone is not compatible with emulsion paints. More specially, silicone is hydrophobic and emulsion paints are water-based which means if you try to paint over caulk, the silicone will repel the paint.
In fact, this incompatibility is the precise reason why silicone is such an effective sealant as it creates a watertight seal that repels water with ease.
However, there are certain types of caulk which can be painted.
Can You Put Paintable Caulk Over Silicone?
Yes, you can apply paintable caulk to silicone. After cleaning the original seal with rubbing alcohol, you simply apply a thin bead of paintable caulk over the silicone and then wait 24 hours to paint over the top.
Most professionals will tell you not to caulk over existing caulk. While this is true in case of old caulk, you can use siliconized acrylic latex caulk over the initial layer of silicone sealant as long as the surface clean.
It’s important to know that nothing sticks properly to old damaged silicone which is why painters often remove the silicone with a caulk remover and then replace it with a new bead of paintable caulk.
Types of Caulk That Are Paintable
There are different types of caulk which are usually made up of either silicone, acrylic-latex, polyurethanes or hybrid polymers.
Some common examples of paintable caulks include the following:
Acrylic Latex Caulk: This water based caulk is often referred to as “painters caulk” because it dries quickly and you can paint over it.
Acrylic/Latex Caulk with Silicone: Siliconized acrylic latex caulk is used when you want the seal to be painted with all the benefits of silicone, such as extra moisture resistance and flexibility.
Also see: Silicone vs. Acrylic-Latex Caulk
Butyl Rubber Caulk – This sticky caulk is paintable using most types of commercial paints and often used on metal joints such as the guttering of a building.
While silicone sealant is superior to polyurethane and hybrid caulk in almost every way, you can often paint over the other two.
Here’s a quick look at how these sealants differ to silicone.
Polyurethanes – Polyurethane sealants form watertight seals that work well in weather conditions which makes them suitable for the exterior of a building. However, this sealant can be used on all types of surface including metal, wood and plastic and it is possible to paint over this type of sealant.
Hybrid polymers – There are several features and benefits, but hybrid polymers sealants essentially combine the elasticity of silicone with the paintability of polyurethane.
Now, you might be asking yourself the following question…
Does Caulk Need to Be Sanded and Primed Before Painting?
You can only sand caulk if the sealant is not made of silicone. It’s also necessary to wait until the caulk is fully dried as sand paper should never be used on a wet surface. This is why professionals use a wet finger to level the surface of a seam and create a smooth dent that results in a clean finish.
Just so you know, you should use a small piece of sandpaper to make sure you only sand the seal itself. It’s also important to wipe down the area with a wet cloth after sanding to remove any unwanted debris or dust from the seal.
But what about priming the caulk?
You can use a shellac spray to prime caulk. After applying a quick spray from this primer, you need only wait five minutes before painting over the top of the sealant.
Shellac spray leaves a smooth and durable finish on the sealant and emulsion paints will then stick as required to the new coating.
How to Paint Over Silicone Caulk?
There are two effective methods to paint over non paintable caulk. Let’s take a look at (Ⅰ) the shellac spray method and then (Ⅱ) applying paintable caulk to a silicone seal:
Method-1: Using a Shellac Spray Primer to Paint a Caulk
- Pick Up Painter’s Tape and a Can of Shellac Spray: You can pick up some blue painter’s tape and a can of shellac spray at any home improvement store. You can then tape up the area around the caulk that you don’t plan on painting and shake the can several times to mix it properly.
- Direct the Nozzle and Spray in Short Bursts: When the can is shaken (more than ten times), you should point the nozzle directly at the caulk and use short bursts to spray the length of the seal. Shellac spray should stick to anything and takes approximately 5 – 10 minutes to dry.
- Get Your Paint Ready: During this waiting time, you can get the paint ready and then paint freely over the caulk once the shellac spray primer has had enough time to dry.
Method-2: Applying Paintable Caulk to a Silicone Seal
- Use Denatured Alcohol: Clean the silicone sealant surface with denatured alcohol. The smooth nature of silicone is one of several reasons why emulsion paint doesn’t stick properly to silicone caulk. Wiping a seam with denatured alcohol can act as sandpaper by roughing up the surface and it only takes approx. 5 minutes to dry.
- Masking Tape: Use painters tape to mask the area if necessary.
- Apply Paintable Caulk to the Silicone Seal: Get a tube of acrylic-latex plus silicone caulk such as the DAP Alex Plus®. Load the tube into a caulking gun and apply a thin layer of caulk over the original seal. The Alex Plus® is usually ready to paint after 30 minutes; but check the instruction label on the bottle for the exact drying time.
- Paint Over the New Seal: You can now paint freely over the top of the seal with any type of emulsion, oil-based or latex paint. Apply a second coat if you can still see the color of the original seal underneath.
How Long Before You Can Paint Caulk?
The time to wait before painting varies from 30 minutes to 12 hours depending on the type of caulk and the manufacturer.
If you are unsure, wait at least 12 to 24 hours before painting over caulk because painting over this seal too soon can result in cracked caulk.
Can You Caulk After Painting?
You can caulk after painting if this caulk will be hidden from view by either molding or trim. You can also get colored caulk matching the paint color.
However, it’s typically best to apply caulk before painting if the caulk will be visible as this ensures a nicer, smoother and more durable seal.
Note: You might be tempted to try the clear caulk, but most of them are not 100% transparent and the glossy surface might look awkward. For more information, read this article on the pros and cons of clear vs. white caulk.
Final Thoughts
While you cannot apply paint directly to silicone caulk, the above methods should help you work around the situation. The correct timing is needed when using a shellac spray or waiting for caulk to dry but the process is rather straightforward with the right tools and products.
You might also want use a paintable caulk in the future to avoid such problems but it’s important to know the difference between caulks and ensure you always use the right one for the job.
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