KILZ Primer Over Mastic (Is It Recommended?)

Considering the many uses mastic has in construction, you shouldn’t be surprised when you find it on your walls or floors.

Whether it’s the regular mastic or the black type, which contains asbestos, you are probably eager to cover it up.

As you may already know, primers are very good at sealing surfaces. And even though there are many types of primers, can you use KILZ primer over mastic? That’s going to be our main focus in today’s article.

KILZ primer

Can You Use KILZ Primer Over Mastic?

KILZ primer can be used on a wide range of surfaces. However, mastic is not one of them.

When you go through the description of the KILZ primer, you will notice that it’s not formulated for use over adhesives or glues. Because mastic is an adhesive, when you apply KILZ, it is likely to fail.

If you must paint a floor or a wall, remove the mastic, apply your KILZ primer, and then paint over it.

What Will Happen When You Apply KILZ Primer Over Mastic?

Two things are going to happen when you apply KILZ over primer. The KILZ will reactivate the mastic, and it will not dry.

You will end up with a sticky substance that can’t be painted. KILZ is an oil-based primer. That is why when you apply it over mastic, it reactivates the adhesive and bleeds through.

Understandably, the thought of applying KILZ primer over mastic seems like an easier solution. However, the results are always catastrophic. Therefore, to be safe, explore other options for sealing mastic.

Will KILZ Primer Seal the Asbestos Inside Black Mastic?

One of the main reasons people apply primer over mastic is to conceal asbestos. So, can you use KILZ primer to seal the asbestos inside the black mastic? Not really.

As mentioned earlier, KILZ primer will reactivate the adhesive in mastic. Therefore, the asbestos will bleed through it.

If you suspect the mastic in your floor contains asbestos, the best solution is to remove it completely. Covering it with KILZ won’t have any impact. At the same time, your home will still be exposed to asbestos which is a health risk.

Are There Alternative Methods of Dealing with Mastic Other than Using KILZ Primer?

Because KILZ primer is ineffective at sealing mastic, are you interested in other methods of dealing with your mastic problem? Here are the top three alternatives on how you can deal with mastic other than using KILZ primer;

• Use a Mastic Remover

Even though it’s the most tiresome and time-consuming method, it’s the best way to deal with Mastic. If you don’t want mastic on your walls or floors, you can get rid of it using a mastic remover.

There are many mastic removers in the market. Good examples include Goo Gone and 3M adhesive cleaner. With either of these products, you can scrub mastic from your floors.

Please note that before removing mastic, you must test it for asbestos. If it contains asbestos, it should be cleaned by a professional company to avoid contamination.

• Apply Cement Overlay

Cement overlays are mostly used to correct imperfections over floors. However, they can also be used to conceal mastic.

The thin cement coating will dry into a rough and paintable surface. One of the perks of using cement overly is that it’s super durable and can also be used to enhance the aesthetics of your floor.

• Use a Special Primer like Perfect Primer

There is one primer brand that is well known for sealing mastic, and it’s known as Perfect Primer. This silky-smooth face primer creates a strong bond with mastic and seals it completely.

Unlike other primers, Perfect Primer is alkyd-based, which prevents it from reactivating the adhesives in mastic. So far, Perfect Primer is the only primer I know that can be used over mastic.

Most primers behave just like KILZ and should be approached with caution when being used in such a scenario. Perfect Primer is also an excellent product for sealing asbestos in mastic.

Which Substrates Can You Use KILZ Over?

Since we have ruled out that KILZ can’t be used over mastic, you are probably wondering what you can use it on. The good news is that KILZ primers are available in various formulas designed for different surfaces.

For instance, you can get KILZ primer formulated for metal substrates. You can also get another KILZ primer designed for drywall or plastic.

Therefore, when shopping for KILZ primer, first determine the substrate you want to use it on. Then look for a formula made for that substrate.

You should also know that there are multi-purpose KILZ primers. These are, however, limited to a particular number of substrates.

Mastic floor

Does KILZ Primer React with Mastic?

You can expect a reaction when you apply KILZ primer over mastic. As mentioned earlier, KILZ is either water or oil-based. When you apply such a primer over mastic, it reactivates the adhesion.

Some people assume that mastic can’t react with other products because it is dry. But the exact opposite is what happens.

KILZ will react with mastic, and the mixture will turn sticky. Even if it dries eventually, the surface won’t be ideal for painting.

If you make the mistake of applying KILZ over mastic and it turns sticky, you will need to re-introduce a mastic remover and get rid of both.

If you have black mastic, it may turn white or ashy. When this reaction occurs, there is a good chance that if asbestos is present, its particles may leak into the environment, which is a huge risk.

Can KILZ Primer Over Mastic Endure Foot Traffic?

Before applying any primer on your floor, it’s crucial to gauge its durability. On other substrates, KILZ primer can withstand a lot of foot traffic.

However, when you apply it over mastic, it will get scraped easily because of the reaction that occurs. It will eventually wear out, especially if applied in a high-traffic area.

How Long Will KILZ Take to Dry Over Mastic?

On recommended substrates, KILZ dries within an hour. However, over mastic, it may take more than a day because KILZ primer reactivates the mastic. And after it dries, it will remain tacky for a few more days.

Also, the number of KILZ primer coats you apply over mastic heavily determines how long it will take to dry. The more coats you apply, the longer it will take.

Should You Hire an Expert to Apply KILZ Primer Over Mastic?

Even if you hire an expert contractor, KILZ primer will not adhere to mastic. It will reactivate the mastic and won’t hold up for very long.

The best part about hiring a contractor is that they will inform you about the risks of applying KILZ primer over mastic. So, this is a problem you will avoid before it’s too late.

However, if you get an inexperienced contractor who doesn’t know how mastic reacts to KILZ, they may land you into a huge mess.

Does KILZ Primer Help with Tile Adhesion to Mastic?

The presence of a primer can help with tile adhesion to mastic. However, you have to wait until it fully dries. Also, if you suspect mastic contains asbestos, you are better off removing it before tiling.

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