The quality of a professional paintbrush depends to a large extent on the characteristics of the filaments used. Stiffness, flexibility, paint-holding capacity, paint release and finish quality are closely related to the geometry and structure of the filament.

Continuous-taper synthetic filaments developed by Nexstar are designed to produce paintbrushes capable of combining control, application performance and finish quality, including with modern water-based paints.

The functions of a professional paintbrush

A professional paintbrush must do more than simply transfer paint to a surface. It must allow the user to control the application, distribute the product correctly and achieve the desired finish.

Key objectives include achieving the required coating thickness, obtaining a uniform finish and providing the precision needed to work on edges, corners, doors, windows, mouldings and other details.

The efficiency of the tool also affects productivity: a paintbrush capable of transferring and distributing paint effectively can help reduce the number of passes required to achieve the desired result.

Paint viscosity and coating thickness

Paints can have very different viscosities, and their behaviour changes during application. During the brush stroke, the paint is subjected to shear forces that can significantly reduce its viscosity compared with its resting state.

An important parameter is DFT (Dry Film Thickness), the final thickness of the coating after drying. It is one of the factors that contribute to the protective performance and quality of the application.

The paintbrush must therefore be able to hold an adequate amount of product and release it sufficiently evenly during the brush stroke.

Finish quality

Smoothness, gloss, consistency and uniformity contribute to the overall aesthetic quality of a painted surface.

This becomes particularly important with water-based paints, which have different drying characteristics from traditional solvent-based paints. The behaviour of the filament during application therefore becomes a key factor in achieving a uniform surface.

The limitations of traditional solutions

Designing professional paintbrushes requires a balance between stiffness, control, paint-holding capacity, paint release and finish quality.

According to Nexstar's technical analysis, chemically tipped straight synthetic fibres may have limitations when used to manufacture paintbrushes intended for the most demanding professional applications.

Natural bristle, while traditionally representing an important benchmark for the industry, may also have limitations with some modern water-based paints, as well as natural variability in the characteristics of the material.

Continuous-taper synthetic filaments

Continuous-taper filaments are designed with a progressive variation in diameter along their length, rather than consisting of a straight filament to which only the tip is subsequently formed.

This geometry makes it possible to influence the mechanical behaviour of the filament and develop different combinations of stiffness, flexibility and control.

The tapered profile is designed to progressively distribute flex along the filament during the brush stroke, while the geometry and arrangement of the fibres contribute to the paintbrush's ability to hold and release paint.

Tailored stiffness and flexibility

One of the most interesting characteristics of continuous-taper technology is the possibility of modifying different filament parameters according to the required performance.

The relationship between base diameter, tip diameter and the length of the tapered section can be varied to achieve different levels of resistance to bending.

This makes it possible to design both stiff or extra-stiff paintbrushes for more viscous paints and softer paintbrushes for lower-viscosity products, while seeking to maintain control, paint-release performance and finish quality.

Control and precision

Paintbrush control is particularly important for precision work. Edges, corners, frames, doors, windows and mouldings require good control of the paintbrush and of the amount of product being applied.

The right combination of filament stiffness and tip geometry can help improve brush-stroke precision without compromising finish quality.

Productivity and application costs

The productivity of a professional paintbrush depends not only on application speed, but also on its ability to achieve the desired result with fewer passes.

According to Nexstar, the application characteristics of continuous-taper filaments can help achieve uniform results in less time. In professional applications, the time saved during painting can have a greater economic significance than the difference in the initial cost of the paintbrush.

Research and performance measurement

The development of professional filaments requires objective evaluation of paintbrush performance.

Nexstar uses testing systems that include a specialised paint-application robot, designed to simulate real paintbrush use and evaluate its behaviour over time.

Laboratory tests also make it possible to measure parameters such as finish quality, gloss and dry film thickness (DFT), providing useful data for the development of new filament combinations.