Blue Squirrel and Blue Thread: Inside the Mack Series 10

In the realm of automotive customization and fine-line artistry, few tools carry the weight of tradition as significantly as the Mack Series 10 pinstriping brush. Known colloquially as the "blue thread" brush or the original "Sword Striper," this instrument has remained the industry standard for over a century. Its presence in the kits of world-renowned artists and novice craftsmen alike is a testament to its enduring design and the specific properties of its construction.

To understand the prestige of the Series 10, one must look beyond the fine lines it produces and examine the heritage and materials that define it. From the cold regions of Siberia to a small workshop in Michigan, the journey of this brush is as intricate as the scrolls it creates.

The Origins of Andrew Mack and the Striping Pencil

The history of the Andrew Mack & Son Brush Company is inseparable from the history of American transportation. The legacy began not in a dedicated brush factory, but in the bustling environment of a wagon manufacturer.

The Era of the Wagon Factory (1865–1890)
In 1865, J.J. Deal established a wagon and buggy factory in Jonesville, Michigan. As the factory grew in reputation for its high-quality carriages, the demand for sophisticated, decorative pinstriping increased. Andrew Mack, born in 1860, eventually became the head striper at the Deal factory. During this period, Mack found himself increasingly frustrated by the quality of the striping brushes available. Most brushes of the era lacked the necessary paint-holding capacity and precision required for the long, continuous lines found on high-end wagons.

The Invention of the Mack Striping Pencil (1891)
Dissatisfied with the status quo, Andrew Mack spent years experimenting with various hair types and brush shapes. He sought to create a tool that offered unparalleled control and a smooth flow of paint. By 1891, he perfected a design that would become known as the "Mack Striping Pencil." The success of his invention was immediate. Recognizing the potential for his brushes beyond the carriage trade, Mack resigned from the Deal factory in 1891 to establish his own enterprise in Jonesville.

A Continuing Legacy
Since its founding, the company has remained a family-led operation. After Andrew Mack, the leadership passed to his son, Glenwood. In 1960, Jon M. "Mike" Fast acquired the company, ensuring that the traditional manufacturing methods were preserved. Today, under the guidance of the Fast family, the company continues to produce its brushes in the United States, maintaining the same handcrafted standards established over 130 years ago.

The Anatomy of a Legend: Blue Squirrel and Blue Thread

The Mack Series 10 is distinguished by two primary features: its 100% unmixed blue squirrel hair and its signature blue thread ferrule. These components are not merely aesthetic choices but are fundamental to the brush’s performance.

100% Unmixed Blue Squirrel Hair

The "blue squirrel" refers to a specific grade of squirrel tail hair sourced from the coldest regions of Siberia and Northern China. The extreme climate in these areas causes the animals to grow hair that is exceptionally resilient, fine, and long.

Unlike many modern brushes that use synthetic blends, the Series 10 utilizes unmixed hair to ensure maximum paint absorption. The natural scales on squirrel hair allow the brush to hold a significant "load" of premium pinstriping enamel paints, enabling the artist to pull long, consistent lines without frequent reloading. This hair type provides the perfect balance of "snap" and softness, allowing the brush to respond to the slightest changes in hand pressure.

The Handcrafted Blue Thread Ferrule

The term "Sword Striper" describes the unique, tapered shape of the Series 10. Each brush is handcrafted in Jonesville, Michigan, without the use of machinery. The process involves meticulous cleaning, shaping, and tying. The signature blue thread ferrule is hand-wound to secure the hair to the handle. This traditional method of construction ensures that the brush maintains its shape over time and provides a level of tactile feedback that mass-produced metal ferrules cannot replicate.

Precision and Sizing for the Artist

The Mack Series 10 is designed specifically for the needs of pinstripers, focusing on fine lines and intricate scroll work. To accommodate different styles and surface scales, the brush is available in a variety of sizes.

• Size 0000 to 000: These are the finest sizes, ideal for very thin, delicate lines and tight, complex scroll patterns.
• Size 00 to 0: Versatile mid-range brushes used for general pinstriping on motorcycles and helmets.
• Size 1 to 4: Larger sizes that carry more paint, suited for long-line work on vehicles and larger-scale custom art.

Each size maintains the classic sword shape, characterized by a long, flat body that tapers to a sharp point. This geometry allows the artist to execute sharp turns and graceful tapers simply by rotating the brush between the thumb and forefinger.

Preservation and Maintenance

Because the Mack Series 10 is a professional tool made of natural materials and traditional adhesives, it requires specific care to ensure longevity. The brush is constructed using water-soluble glues that can be compromised if handled incorrectly.

Proper Cleaning Procedures

1. Use appropriate solvents. Clean the brush thoroughly using a high-quality mineral spirit or specialized brush cleaner intended for enamel paints.
2. Rinse until clear. Ensure all pigment is removed from the "heel" of the brush (the area near the thread), as dried paint in this section will cause the hairs to spread and lose their shape.

Storage and Oiling

• Apply brush oil. After cleaning, apply a generous amount of brush oil or light mineral oil to the hair. This keeps the natural fibers supple and prevents them from becoming brittle.
• Reshape the hair. Gently pull the hair through your fingers to restore the sword shape before storing.
• Store flat or hanging. Place the brushes in a durable metal brush case to protect the delicate tips from being bent or crushed.

The Enduring Appeal of the Series 10

In an age of digital graphics and machine-cut vinyl, the hand-painted line remains a symbol of authenticity and skill. The Mack Series 10 is more than just a pinstriping tool; it is a link to a 19th-century craft that continues to thrive in the modern custom culture. Its construction reflects a commitment to quality that has not wavered since Andrew Mack first sat at his bench in the Deal wagon factory. For those who value the human touch and the precision of the hand, the blue squirrel and blue thread remain the ultimate instruments of expression.