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Sound Deadening Spray for Cars – Everything You Need to Know

James Benchman
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by James Benchman

Cars, generators, and even kitchen appliances make life more convenient, but they can also contribute to noise pollution, distractions, and disrupting the peace.

Road noises, loud generators, and thin walls are just a few examples of how helpful technology can become distracting and noisy. As a solution, many people invest in mats, foam, and insulation that deaden noise, cancel vibration, and boost the sounds they want to hear.

However, these materials can also be expensive, heavy, and hard to apply.  Not to mention taking them off can be even more of a challenge than putting them on.

Instead, consider using sound deadening spray — quick to use and easy to apply, it’s one of the most beneficial products for short-term soundproofing.

Below, you’ll find everything you need to know about what soundproofing spray is, how it works, and how it compares to other materials.

See Also: Best Automotive Sound Deadening Material Reviews

What is Sound Deadening Spray?

Sound Deadening Spray

Sound deadening spray allows you to soundproof certain machines and spaces by covering it in layers of liquid soundproofing material.

Not only is it cheaper than other materials, but it’s also the easiest to use.  You simply spray it on any vehicle, machine, and in any place that you need to soundproof.

1. Why Use it?

Even if you already own some sound deadening materials or plan on getting some, having spray on hand can be extremely beneficial.  This is because the spray can be used to fill gaps between other soundproofing materials.

Fortunately, not only is the spray great for soundproofing certain areas, but also for dampening noisy machines such as kitchen appliances and generators.

Although it’s not as effective as more expensive materials such as mats, foam, and insulation, it can come pretty close to it after a few layers have been applied.

2. What is it Made of?

Sound deadening spray is the liquid version of mass loaded vinyl sheets, which is more expensive than materials such as mats but also one of the most effective.

The materials of spray are almost identical to the materials of mass loaded vinyl, which makes also makes it resistant to heat.

But if it’s made with some of the same materials as the best sound deadening materials, then how come soundproofing spray is one of the least effective?  It depends on how much you use.

How Does Sound Deadening Spray Work?

In order to understand how sound deadening materials work, a basic knowledge of sound waves is necessary.

According to Universal Class, sound is a mechanical wave that’s produced by vibrating objects.  Once produced, the waves travel from one point to another, making sounds as they go.

When an object vibrates, the air around it is set into motion and the sound produced is turned into heat energy.

It is the job of the sound deadening material to absorb the sound waves produced in order to make them disappear faster, eliminating the noise.  When using the materials to soundproof a room, they block sound to prevent its transmission between the rooms.

Regardless of which product you’re using, every type of sound deadening material uses these physics principles of sound waves in order to perform their best — including sprays.

They are effective in doing so, as APS Physics even conducted a study that concluded liquid foam sound deadeners can block the transmission of ultrasound frequencies entirely.

For example, when you cover a certain machine in sound deadening material, it absorbs the noises being made by that machine before they can be transmitted to the surrounding atmosphere.

On the other hand, when you cover a specific room or vehicle in sound deadening material, it absorbs all external noise before they can be transmitted into the space you’ve soundproofed.

Sound Deadening Spray vs. Mats

Automotive Car Sound Deadening

While sound deadening mats and spray-on materials do have several things in common, they also have quite a few differences.

Spray-on sound deadeners are notorious for chipping after being applied.  Not only are they supposed to absorb heat and sound waves, but they’re also designed to fend off rust, in which case chipping is unacceptable.

However, cracking and chipping may be the result of a cheaper product.  Sound deadening mats are known for being more expensive, but as a result, they’re also expected to do much more and last longer.

Mats are designed to be long-term solutions for noise deadening, while spray-on deadeners are designed to be used for the short-term.

Because of this, sprays are much easier to apply compared to mats, which can take hours to install in a vehicle.  Plus, many mats are extremely hard to remove.

Sprays can also leave behind an unpleasant odor.

Many sprays contain a scent similar to rubber when first applied, and very few have been deemed ‘odor-free.’  The majority of mats, on the other hand, boast about sparing you the smell.

Not only are sprays easier to apply then mats, but they can also cover spaces that are hard to reach.

Installing a mat can become even more strenuous when trying to cover corners, rough edges, and other unique spaces.  However, sprays save you that trouble.

Which High Quality Spray Do We Recommend?

While most sound deadening sprays tend to be lower quality, short-term solutions, there are a select few who have formulated a high quality spray product. One such example is Spectrum spray on deadener by Second Skin Audio, which can be used as a substitute for sound deadening mats.

Second Skin’s Spectrum is an acrylic polymer designed for those who want quality, but would prefer to spray on their deadener. Spectrum works just as well as a butyl sound deadening mat when applied to the recommended 2mm thickness (and you can go thicker if you want). Because it’s water based, there’s no burnt rubber smell. Spectrum is durable too, as it won’t chip unless it’s exposed to very heavy impact.

Second Skin sells their sound deadening spray in a paint container, not an aerosol can. The nozzle on an aerosol can is just too small to spray rubber particles big enough for effective deadening. If you care about performance and don’t want to deal with that burnt rubber smell, use an HVLP gun and compressor to spray on a sound deadener that actually works.

Spectrum Liquid Sound Deadener

Second Skin Spectrum Deadener
  • Water based viscoelastic polymer
  • Formulated by Second Skin for high-end damping and adhesion
  • Odor free
  • Heat rated to 400 F
  • Made in the USA

How to Use Sound Deadening Spray

We’ve already established that spray-on sound deadeners are much easier to use than other materials, such as mats, foams, and insulation.

But how exactly do you apply it? Is it really just as easy as spraying a few corners, walls, and edges?

Below, you’ll find the simplest step-by-step process for applying a spray-on sound deadener to any car.

Step 1 – Prepare Your Vehicle

Prepare The Vehicle

Before you cover anything in liquid spray, you’re going to have to take some things apart.

The ultimate goal of the first step is to reach the sheet metal of the car, just like you would when installing mats.

Soundproofing the inside of the car other than the doors is often the trickiest part of the vehicle. This is because you must remove the headliner, seats, and carpet before installing.

However, under the hood, in the trunk, and on the roof are all a bit easier.

Once you’ve reached the sheet metal, it’s time to clean.  There shouldn’t be any dirt or rust remaining when you go to apply the spray, the reason being all sound deadening materials will make your vehicle a bit water-resistant, which can ruin the metal if rusted.

The best way to clear your parts of rust and dirt is to sand it down.  If you need something a little more heavy-duty, try treating it with a rust encapsulator.

Step 2 – Gather Tools and Safety Materials

Once you’ve reached the sheet metal and everything is cleaned, there’s one more thing you must do before getting straight to business.

Consider wearing gloves, a face mask, and a hat when applying the spray to avoid getting it in your eyes and on your skin.  Also, keep in mind that when dealing with any kind of liquid spray, you risk getting dirty.  Therefore, wear something you don’t mind getting stained.

Depending on which brand of spray you’re using, you might need an additional spray gun and mixer.

Some sprays, e.g Second Skin Spectrum, come with a kit that includes tools such as the spray nozzle, canister, mixing drill tip, and a wet mil gauge.

If the liquid spray comes in a can, open it (after you’ve gathered all the parts) and mix it for a few minutes over a piece of cardboard or towel.

Step 3 – Apply the Sound Deadener

Now that you’ve gathered the correct materials, taken proper safety precautions, and reached and cleaned the sheet metal, you can start applying the sound deadener.

When using spray-on deadener, be sure to spray it at least 8 inches away from you and use a mask to avoid contact with your face.

After about 20 minutes, the first layer will be dry and you can go back in for a second layer.  If you plan on applying more than two layers, continue to let each one dry for at least 20 minutes.

Since most people use it only for short-term problem solving, most bottles don’t supply an amount sufficient enough to give the same results as expensive mats, foams, insulation, and sheets.  As a result, more than two layers should be applied for better results.

In order for the deadener to work at its best, the first layer should be about 20 mils thick.  You can measure it using the wet mil gauge.  Each layer following the first should also be 20 mils thick.

Finally, after approximately 6 hours all layers of the spray will be dry enough to paint over and polish.  While this isn’t required or necessary, many people prefer to do it.

Step 4 – Re-assemble

Once all layers of the spray are 20 mils thick and completely dry, you can begin putting everything you removed from the car back into place.

Depending on how much you had to take out, this process can be either pretty quick or rather time-consuming.

After everything has been put back in its proper place, double check to guarantee it’s all secure. Now the process is finished!

Sound Deadening Spray is the Ideal Solution for all Your Short-Term Noise Problems

Why use hard-to-install sound deadening materials that take up loads of time to install when you can keep a handy can of spray that takes minutes to apply?

Sound deadening spray is the perfect solution for those who want to reduce the noise made by their machines, kitchen appliances, or soundproof small rooms.

Not only are they more affordable, but they’re also more convenient.

You shouldn’t have to sacrifice time and tons of money for a peaceful and quiet room.  With sprays, you can soundproof a room in minutes instead of hours.

Photos Credit: dieseltruckresource.com | toyota-4runner.org

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About James Benchman
James Benchman
James is an Automotive Mechanic with over 20 years experience and 300+ car repairs. He is an expert with cars and has worked with different models from the biggest brands. James is a Mechanic , Husband , Father of 3 , and head of content at Caraudiologic. Learn more about us
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