The Army Painter Paint Mixing Balls, 5.5 mm - Rust-Proof Stainless Steel Mixing Balls, 100 PCS Review (2026)

The problem these balls solve

Acrylic paint in a dropper bottle settles over time, with pigment and heavier additives sinking while the binder rises, and shaking the bottle alone often fails to fully remix a paint that has sat unused for weeks or months. The Army Painter's answer is a bag of small stainless steel balls sized to drop into a standard dropper bottle and physically agitate the settled paint back into suspension every time the bottle is shaken before use. This is a well established fix across the hobby, similar to the agitator ball found in a can of spray paint, just scaled down to fit a 12 to 18ml acrylic dropper bottle rather than a full sized aerosol can.

Material, size and what is included

Each ball measures 5.5mm in diameter and is made from stainless steel specifically chosen to resist rust, since a corroding metal ball inside a paint bottle would eventually discolor the paint or leave rust flecks in a wet brush stroke. The Army Painter's own instructions recommend adding two balls per bottle rather than one, since two balls striking each other and the bottle walls during shaking break up settled clumps more effectively than a single ball rolling on its own. At 100 pieces per pack, that is enough for around 50 bottles at the recommended two per bottle rate, which covers most painters' full paint racks with room to add balls to new bottles as a collection grows.

Using them without losing paint or balls

Adding a ball means opening the bottle fully rather than just squeezing the dropper tip, so the dropper insert needs to come out, the ball goes in, and the dropper is reseated before capping the bottle again. This is a bit fiddly compared with paints that ship with an agitator ball already inside, and it is easy to lose a tiny 5.5mm ball on a cluttered desk while doing this across dozens of bottles in one sitting. Once installed, the balls stay in the bottle permanently through normal use, so the setup cost is really a one time task per bottle rather than something repeated at every painting session.

Fit and compatibility across paint brands

At 5.5mm, these balls fit comfortably into the wide necked dropper bottles common among Citadel, Army Painter and Vallejo Xpress ranges, but some narrower or older bottle designs have a neck too tight for a ball this size to pass through without removing the dropper insert entirely first. Rival products in a smaller 3mm size exist specifically for bottles with tighter openings, so painters with a mixed collection of bottle styles may need to check neck width before assuming one size works everywhere. Compared with simply shaking a bottle by hand for a long time, or using a paint shaker device, mixing balls are the cheapest and most portable solution, fitting inside the bottle itself rather than requiring extra equipment or a long shaking routine.

Who benefits from a bag of these

Anyone with more than a handful of dropper bottle acrylics will notice the difference these make, especially bottles that only get used occasionally and have time to settle between sessions. Painters who buy paint in small dropper bottles rather than the larger pots that stir with a brush are the primary audience, since pots do not have the same settling and remixing problem in the same way. The main caveat is neck width on less common bottle brands, so it is worth test fitting one ball into a spare bottle before committing to adding them across an entire paint collection at once.

Frequently asked questions