Both acrylic and silicone caulking has a similar function.
To seal cracks, insulate against cold or hot air, and prevent moisture from passing through, but what they are made from will dictate their use for your project.
Understanding the attributes and differences between acrylic and silicone caulking will help you choose the right one.
So, let’s dive right in by knowing about both…
Also known as latex-based caulks this type of caulking tends to be more popular than its silicone counterpart.
Mostly because acrylic caulking is easy to use and can clean up quickly.
In addition, the clean seal that it provides is perfect for painting projects.
Cracks in the woodwork, ceiling, and walls can be quickly filled and fixed with acrylic caulking.
Acrylic caulking is an excellent insulator and is perfect to use around doors, electrical outlets, and windows as well.
Its one downside though is that it does not do well when coming into contact with water.
When exposed to too much moisture, acrylic caulks tend to shrink which will create gaps over time.
Sometimes called rubberized silicone, this is a strong caulking product that keeps its flexibility over time.
Unlike acrylic caulking, silicone is quite good as a waterproof seal.
It will not shrink or crack when exposed to water. This is why you often see it used on toilets, showers, tubs, sinks, and other plumbing fixtures.
Its waterproof nature also makes it perfect for outdoor use, especially under wet weather conditions.
This is why silicone caulking is often used on the outside of homes and other structures that require waterproofing.
However, it’s one downside is that because silicone (present in the caulk) repels water, it also means it repels paint.
Therefore, it is not recommended that you use silicone caulking for painting projects.
It will keep the paint from bonding and can cause peels and cracks fast.
Acrylic vs. Silicone Caulking
Although silicone and acrylic caulk is similar in nature and looks rubbery when cured on the surface, the difference lies in the environment and surfaces where they can be used.
Both acrylic and silicone caulking can be used to seal up most gaps in home interiors.
The exception is that silicone is best used for humid areas such as the bathroom and kitchen.
The only exception would be if these areas are to be painted, in which case acrylic caulking is recommended.
In addition, for outdoor applications that will not be painted, silicone is the superior caulking product.
The good thing is it’s available in various different colors, (including clear) which does not turn yellow very fast.
|Cannot be painted over
|Good for indoors
|Good for outdoor usage
|Is non-elastic and not waterproof
|Elastic waterproof sealant
|Can shrink or crack in the water
|Does not shrink or crack in the water
|Can last for approximately 5-6 years
|Can last for approximately 15-20 years
|Dries quickly and becomes very hard when dry
|Cold and heat resistant, better for larger joints
When to use polyurethane caulk?
Although silicone caulk adheres very well to almost any material, it does not work very well to seal around wood surfaces.
That’s where polyurethane caulk comes in handy.
Polyurethane caulk is known for its flexibility and can be used on wood and other surfaces that need to be painted.
However, the main drawback of polyurethane caulk is it does not hold up as well as silicone caulk on surfaces that are exposed to direct sunlight.
So, if you need to caulk and paint wood surfaces that are away from direct sunlight it’s good to use polyurethane caulk.
Polyurethane caulk is easier to apply, and clean up than silicone caulk. Plus, it is less expensive.
Is painter’s putty the same as caulk?
Although caulk, spackling compound, and putty are all used to fill holes and gaps by painters they are not all the same materials.
The key difference is in their flexibility and ability to resist moisture.
Where caulk is a flexible coating that resists moisture, putty and spackling compound are the products that dry hard and aren’t water-resistant.
Tips for Applying the Caulking
To apply the right amount of caulk, it is recommended that you cut the tip at a 45-degree angle.
This will allow for better control of the amount of caulk being applied to the opening.
You should cut as small an opening as possible, so you can control the exact amount of caulk that is needed.
The goal is to create a neat line of caulk that does not require any messy clean-up.
Use good quality caulk, clean the surface thoroughly, and apply it directly to the opening.
Once it is set, use a primer, sealer, or undercoat to cover the caulk if it is to be painted over.
Instead of trying to apply a single, big glob of caulk, think about applying a few small layers instead.
This will not only seal up the opening better it will reduce the cleanup time.
Plus, be sure to have a good scraper and some rags or clothes to speed up the cleaning process.
Given how fast the caulk can dry, you should clean any tools and equipment that touch the caulk quickly to avoid any issues later on.
Should I Caulk or Paint the Surface First?
If you need to paint the surface you are caulking, remember – latex-based caulks are supposed to be used under the paint as they are paintable and long-lasting.
Then comes the sequence in which you need to apply the paint or caulk.
Usually, for indoor surfaces, you should put the caulk first and then the paint.
This will hide the caulk and will make the surface look better.
However, if the surface is exposed to polluted air particles, dirt, or grime (like outdoors) it’s best to do the opposite.
Since the exterior surfaces are not protected and are exposed to various harmful materials (including harsh UV sun rays and moisture), the specks of dirt can stick to the caulk – if you do the caulking first.
These dirt particles will affect the paint adhesion and can become visible if you paint over the caulking afterward.
It’s therefore good to do the exterior painting first and then follow up with caulking.
There is however a drawback when you follow this outdoor caulking & painting sequence – your exterior designs will not look pleasing with the caulk residue left behind.
To fix this issue, it’s good to choose a clear transparent caulk that becomes invisible after application.
You can even pick the same color caulk (from the range of colored caulks available) which will blend perfectly well with the exterior paint colors.
How Long Should I Wait for Paint to Dry Before Caulking?
Although caulking is done before painting in most conditions, you may sometimes need to caulk after painting.
Like when you have painted your newly installed tile backsplash, door, or window and then realized there is a gap you need to fill with caulking.
To fix that gap or holes, the paint needs to be completely dry before caulking, or the caulk won’t adhere to the surface and will just peel right off.
Most paint labels will give a suggested dry time for how long you should wait before caulking, which is typically 24 hours.
With that said, how soon after painting the surface can you caulk will depend on various factors which will include:
- Type of paint and number of coats you applied
- Paint application methods- like spray, brush, or roller
- Ventilation and weather conditions including temperature and humidity
So, to be on the safe side, you can test the paint by gently pressing your finger into the area.
If the paint comes off on your finger, it’s not dry enough and you’ll need to wait a bit longer.
If the paint is dry to the touch, you can go ahead and caulk.
So, what’s the verdict? Acrylic or silicone caulking for your project?
In general, acrylic caulking is a better choice for indoor projects since it doesn’t emit fumes and is easy to clean up.
Silicone caulking is a better option for outdoor projects because it resists weathering and moisture.
However, there are some exceptions to this rule – if you need a caulk that will withstand high temperatures, for example, then silicone would be the best option.
Ultimately, the best way to choose between acrylic and silicone caulking is to consider the specific needs of your project.
Jack Luis is a semi-retired painter who loved painting his clients’ ideas on their walls.
He had worked as a painter for over a decade serving customers in areas such as Charleston, Mount Pleasant, Beaufort, and Georgetown, SC (South Carolina). Today in his free time, he likes to read and write about the newer techniques implemented in his profession. You may read more about him here or get in touch with him here.