Rosemary & Co Pure Ultimate Bristle Filbert Series
About the Ultimate Bristle Filbert
The Ultimate Bristle Filbert is Rosemary & Co's flagship natural bristle filbert — handmade in England using carefully selected natural bristle set in a double interlock construction. Two equal amounts of hair are placed opposite each other with the natural curve facing forward, giving the brush a confident, loaded stroke with real spring and character.
This is an expressive brush, not a precision instrument. It's built for painters who want visible texture, organic marks, and a stroke that carries energy across the canvas. The filbert shape — that rounded, slightly tapered flat — blends the coverage of a flat with a softer edge, making it a favourite for portrait painters, landscape artists, and anyone working in oils or heavy-body acrylics where brush character matters.
The bristle offers medium-firm spring with a deliberately textured, grainy release. It holds its shape under heavy paint and loads well for strong directional strokes. Compared to synthetic filberts, expect more splay and more texture — that's by design. If you prefer a cleaner, more controlled edge, Rosemary & Co's Ivory Filberts (synthetic) are worth considering. If you want raw, painterly marks with real bristle character, this is the one.
Best For
Medium
Oil — the natural bristle's firm spring and textured release are perfectly suited to oil painting. The brush loads well with heavy paint and holds its shape through long strokes.
Acrylic — works well with heavy-body acrylics where you want organic, grainy marks. Be mindful of cleaning promptly — acrylic dries fast and is much harder on natural bristle than oil.
Technique & Use Case
Portrait painting — the filbert's soft edge is made for skin tones and figurative transitions
Landscapes & still life — organic marks with real brush character
Blocking in — loads paint and covers ground efficiently
Blending & glazing — the rounded edge softens transitions without hard lines
Expressive brushwork — texture-forward strokes where the brush's mark is part of the painting
What This Brush Is Not Ideal For
🔸 Tight, precise marks — natural bristle splays more than synthetic. If you need crisp, predictable edges, a synthetic filbert will serve you better.
🔸 Smooth blending — these brushes leave texture by design. For glassy-smooth blending, synthetic or sable brushes are a better match.
🔸 Easy cleanup — natural bristle is harder to clean than synthetic, especially with acrylics. A good brush soap is essential.
Sizes in This Series
Short handle: sizes 0–14 | Long handle: sizes 0–16
| Size | Diameter (mm) | Brush Length (mm) | Best For |
|---|---|---|---|
| 0 | 4.0 | 11.5 | Detail work, small-scale blending |
| 1 | 5.5 | 13.3 | Detail work, portraits (small scale) |
| 2 | 6.2 | 15.5 | General painting, glazing, portraits |
| 3 | 7.5 | 18.5 | General painting, blending, transitions |
| 4 | 9.5 | 22.5 | Blocking in, landscapes, basecoating |
| 5 | 10.6 | 23.8 | Blocking in, broader blending, still life |
| 6 | 12.1 | 25.6 | Broad strokes, landscapes, texture work |
| 7 | 13.8 | 27.7 | Broad strokes, heavy coverage, expressive work |
| 8 | 14.8 | 30.5 | Large-scale blocking, impasto, bold texture |
| 10 | 19.5 | 34.1 | Large canvases, broad coverage, expressive marks |
| 12 | 23.5 | 38.6 | Large canvases, heavy blocking, underpainting |
| 14 | 29.7 | 43.7 | Very large work, murals, broad underpainting |
| 16 | 34.2 | 46.7 | Very large work, murals, scene-scale blocking |
Brush sizes are not standardised across brands. A Size 4 in this series may differ from a Size 4 in another brand. Dimensions shown are from the manufacturer's published size chart. Short handle available in sizes 0–14; long handle available in sizes 0–16.
Care & Maintenance
Natural bristle brushes are hard-wearing but reward proper care. A well-maintained filbert will last for years — protect your investment with good habits from day one.
Cleaning
During painting: Wipe excess paint regularly. With acrylics, never let paint dry in the bristles — once cured it's nearly impossible to remove.
After painting: Wash thoroughly with a dedicated brush soap, then reshape the filbert edge with your fingers before leaving to dry. We recommend The Masters Brush Cleaner & Preserver — we stock it and it works brilliantly with natural hair brushes.
Storage
Dry the brush fully before storing upright or flat. A brush roll or protective tube helps maintain the filbert profile over time. Never store with the bristles compressed or bent.
What Not to Do
🚫 Don't leave the brush soaking in water or solvent — it damages the bristles and loosens the ferrule
🚫 Don't let acrylic paint dry in the bristles — clean promptly after every session
🚫 Don't scrub aggressively enough to deform the filbert edge — these brushes are firm, not indestructible
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