Why Are There Marbles In Spray Cans?


Last updated: February 14, 2024

Dissecting the Roles of Marbles in Spray Cans

Why are there marbles in spray cans

Painters have a normalcy of shaking spray cans before getting to work. Shaking the can rattles the marble inside, and that’s an important step before you start painting.

It is typical to assume the marble inside spray cans aren’t necessarily useful. Nevertheless, despite their small size and noisy nature, the marbles have more to offer. 

In this article, I will explain the role of marbles in spray cans and how they impact your spray painting work. Let’s dive in.

Why Are There Marbles In Spray Cans?

The marble in the spray can enable easy mixing of the paint and propellant. As you rattle the marble, the propellant emulsifies the paint uniformly, enabling the paint to come out evenly via the nozzle as an even mist. Also, with time, paint pigments tend to separate, and moving the ball inside around breaks the clumps and mixes the sediments into a consistent blend.   

What is the Ball Inside Spray Cans?

The ball inside the spray can is known as a pea. As you shake the spray can, the rattle noise comes from moving the pea up and down the can. 

The common materials used to make the pea are metal, glass, or plastic. Some spray cans contain one or two balls, depending on the manufacturer’s preference. 

Initially, manufacturers didn’t have spray cans with a ball inside, and mixing the paint was a vigorous and intense activity for painters. The presence of the ball makes it much easier to mix the paint and propellant while spray painting. 

Why Are There Marbles in Spray Cans

The marbles in spray cans play significant roles, such as:

  • Shaking the marble assists with mixing the paint and propellant.
  • The marbles ensure an even paint consistency without the formation of clumps.
  • With the aid of the marbles, you can avoid over or under-painting.
  • The marbles break the paint pigment clumps that form and clog the nozzle.
  • You can use the marble’s rattle noise to estimate the paint left. The louder the marble, the less the paint.

What is The Purpose Of The Ball In Spray Paint Cans?

A simple spray can design comprises a nozzle, seal, dip tube, ball bearing, and compressed gas, which acts as a propellant. Since the paint is liquid, so is the propellant as it is pumped into a sealed can under high pressure. 

Under normal pressure, the propellant maintains its liquid state, lacking enough room to expand into a gaseous state. 

When you press down the nozzle, everything changes because you reduce the pressure inside the can. With reduced pressure, the propellant expands into a gas, pushing the paint up the dip tube through the nozzle. 

The trick is to shake the can and rattle the ball bearing; by doing so, you mix the propellant and the paint evenly. Also, the products come out of the nozzle as a fine mist. 

What Is The Ball Inside Spray Cans Made Of?

The pea is typically made of glass, metal, or plastic:

Glass: Glass is ideal for spray can balls as it doesn’t react, interact, or corrode with any chemical components in the paint or propellant. This quality helps increase the integrity and durability of the paint. 

Metal: Metals, especially aluminum and stainless steel, are often used to make the balls inside spray cans. Metal balls are effective for mixing the paint and propellant evenly. Also, pea sized metal ball is heavier and less fragile than glass, meaning painters are less concerned about breaking the ball while shaking the spray can.   

Plastic: Plastic balls have advantages, like they are corrosion-resistant and don’t interact or react with the chemicals in the spray can. Their lightweight helps prevent clogs at the nozzle, and plastic balls rarely damage the spray can’s interior.   

Why are there Glass Marbles in Spray Cans

The glass marble ball in the spray cans helps mix the paint and propellant into an even consistency. The paint’s pigments tend to separate, and when you agitate the marble inside, it blends everything up evenly.

The propellant paint mixture is usually a gas, and the paint is liquid. The glass marble helps mix the liquid and gas so the paint comes out of the nozzle as a consistent blend of mist. 

Glass marbles are also a better option as they don’t corrode or react with the chemicals present in the contents of the spray can. 

What Is The Size Of The Ball Inside Spray Cans?

The size of the ball inside the can differs from manufacturer to manufacturer. The standard size is between 1.4 to 3.8 inches in diameter. An ordinary marble is approximately 1.5 inches in diameter. The size of the pea also depends on whether the material is metal, glass, or plastic. 

If you are curious about the pea inside spray paint, you can open an empty can. Only conduct this experiment using the proper tools and protective gear to avoid spillage and direct contact with harmful spray paint chemicals. The kind of ball you find inside different brands will differ in material, size, and number.  

How Does the Ball Affect Spray Paint Work?

The essence of the ball is to ensure proper mixing of the paint and the propellant and dispensing it in a fine mist. The paint and pressurized gas only mix when you shake the can and rattle the ball bearing. Without the ball, the paint passing through the dip tube to the nozzle would be clumped. 

Here are a few tips to get a glossy, and even finish with spray paint:

  • Thoroughly clean and sand the surface before spray painting for the paint to adhere better.
  • Purchase good quality spray paint, and as you prepare to start painting adequately, shake the can to rattle the ball bearing. Proper shaking blends the paint and propellant into an even mist.
  • Hold the spray can 6-8 inches away from the surface and apply light, even strokes.
  • Thin paint coats dry faster and appear even than thick coats.
  • Keep an even pressure while painting to avoid over or under-spraying some areas.
  • Keep rattling the ball bearing the entire time as you are painting to maintain an even paint consistency.

Why Do Spray Paint Cans Rattle?

The rattle sound results from the ball inside moving up and down the spray can while you shake it. The noise can vary depending on whether the ball bearing is metal, plastic, or glass. 

Shaking the spray can promote mixing the paint and propellant, blending the two into a consistent color, texture, and viscosity. 

The rattle also helps you estimate the paint remaining in the can. The louder the noise, the less paint is left. The rattle noise increases because there is less paint and propellant, causing less pressure inside the can, allowing free ball-bearing movement.  

Why Do You Need To Shake Spray Cans?

You need to vigorously shake the spray can for at least 60 seconds before you commence your painting. This encourages proper mixing of the pressurized gas and ball bearing, ensuring the paint moving up the dip tube and out of the nozzle is a fine and even consistency.

Additionally, it would be best if you kept shaking the can so the ball bearing keeps mixing to achieve a consistent mist and prevent the formation of clogs or clumps. 

What Are The Consequences Of Not Shaking A Spray Can?

Lack of or insufficient of the spray can result in some ugly consequences, for instance:

  • If you don’t shake the can, the paint and propellant don’t mix as intended; hence, the paint comes out as an inconsistent mist.
  • Not shaking the can encourages the formation of clumps and clogs that block the nozzle.
  • With time, the paint pigment settles at the bottom of the can, and if you spray without shaking, the paint job appears uneven and patchy.

Shaking the spray can is the key hack to achieving an even and smooth finish when spray painting.   

What To Do If Spray Paint Can Ball Stuck?

Sometimes, the spray paint ball gets stuck, causing the paint to clump up or form a ball. Here are some measures you can take when that happens:

  • First, try shaking the can more vigorously than usual.
  • Then, if that doesn’t work, tap the spray can on a hard surface and shake to listen for the rattle.
  • Sometimes, that doesn’t yield results, so you can try heating the can. Please don’t place the spray can on a direct flame. as most spray paints are flammable. Instead, place the can inside boiling water for a while then try rattling the ball bearing again.

FAQs: Why Are There Marbles In Spray Cans?

Below are well-researched answers related to the marbles inside spray cans:

Do all aerosol cans have a ball inside, like spray paint cans?

Aerosol cans made of metal or aluminum, like spray deodorants, insecticides, or hairspray, have the pea inside. The ball helps mix the compressed gas and the liquid product inside into a perfect vapor blend.

What is the shaky thing in spray paint cans?

The shaky thing in spray paint can is known as a pea. The pea is made of materials like metal, plastic, or glass. You can find spray cans with one or more balls inside. Two balls yield better results by emulsifying and mixing the paint and propellant. 

Can you prevent a spray can from rattling?

It’s only possible to prevent the rattle from the pea if it’s made of metal. Attach a strong magnet at the bottom of the spray can, which will attract the metal ball, stopping the rattle. This trick is helpful when carrying spray paint in your backpack, and the ball bearing won’t stop rattling.  

Can You Remove The Ball From Spray Cans?

Yes, you can get curious and decide to remove the ball from a spray can. It’s best if you try removing one from an empty paint to avoid wastage and gross spillage. Also, wear proper gear and use the right tools to avoid direct contact with the chemicals and gasses in the spray can. Dispose of the spray cans according to local disposal laws.    

Why do they put marbles in spray cans?

Manufacturers place marbles inside spray cans to facilitate the mixing of the paint and propellant once you shake the can. The marble makes the mixing process easier and simpler.

Bottom Line: Why Are There Marbles In Spray Cans?

Marbles in spray cans seem like an odd topic. However, if you often use spray paint or are a newbie to spray painting, the rattling noise will be a common sound. It is normal to get curious to find out the marble, and there is no harm in understanding the basic mechanism that applies to spray cans.

The ball inside aerosol cans, especially spray cans, is known as the pea. The pea is typically made with metal, glass, or plastic. 

The pea enables the mixing of the paint and pressurized gas inside the spray can so a fine, consistent mist is pushed through the dip tube and out of the nozzle. Despite its humble size, the pea does a magnificent job.

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