Water brush 3.9 mm Pentel Aquash — round tip, refillable water reservoir

Water brush 3.9 mm Pentel Aquash — round tip, refillable water reservoir is a portable brush designed for watercolor, ink and mixed-media techniques. The 3.9 mm round synthetic tip delivers a fine yet flexible point for detail, lines and delicate washes while the built-in refillable reservoir provides a controlled, continuous supply of water without the need for a separate water container. The brush is suitable for studio and field use where compact, mess‑free water application is preferred.

Advantages

The brush combines a consistent water feed with a resilient synthetic round tip that maintains shape during repeated use. Its refillable reservoir reduces interruptions during painting sessions, and the compact design supports travel and outdoor sketching. The controlled flow helps achieve smooth gradients and blending between pigment layers and enables quick wetting of paper for washes and effects.

Suitable for

• Watercolor sketches and washes
• Ink and brush-pen blending
• Illustration and detail work
• Travel sketching and plein air studies
• Mixed-media and hobby painting

Key specifications

• Tip type: round synthetic fiber
• Tip size: 3.9 mm (fine round point for detail)
• Reservoir: refillable water chamber for controlled flow
• Compatibility: suitable for water-based pigments, inks and diluted media
• Body: lightweight, portable design for field use

How to use

Unscrew the brush body to fill the reservoir with clean water or a water-based medium. Reassemble the brush and gently squeeze the reservoir to initiate water flow to the tip; control flow pressure as needed for washes or fine lines. Use the rounded tip for tapered strokes and detail, and adjust the amount of water to vary pigment dilution and edge softness. Rinse the tip periodically when changing colors or media to avoid contamination.

Usage recommendations

For best results, use quality water-based paints and diluted inks. Clean the tip after each session with water and gently reshape the bristles if needed before storing. Avoid strong solvents or undiluted acrylics that can damage the synthetic fibers.