Paintbrush Shapes and Hair Types: A Guide for Every Medium
Paintbrushes are described by three things: the shape of the head, the size number and the hair. Rounds and flats cover most painting, while filberts, brights, fans, riggers, angles and mops do more specialised jobs. Soft hair such as sable, squirrel or soft synthetic suits watercolour, while stiff hog bristle or firm synthetic suits oil and heavy acrylic. Size numbers are not standard between makers, so compare actual brushes rather than relying on the number alone.
This guide explains each shape, how sizing works, which hair suits which medium, and how to clean and store brushes safely.
Brush shapes and what they do
| Shape | What it looks like | Typical uses |
|---|---|---|
| Round | Hairs gathered to a pointed tip | All-round brush: lines, detail and small washes; marks change with pressure |
| Flat | Square end with longer hairs | Broad strokes, filling areas, crisp edges; the edge draws thin lines |
| Bright (short flat) | Square end with short, stiffer hairs | Controlled, textured strokes and thicker paint, especially oil and acrylic |
| Filbert | Flat brush with a rounded, oval tip | Blending, soft edges, petals and portraits |
| Fan | Thin layer of hairs spread in a fan | Blending, foliage, grass and texture |
| Rigger / liner | Very long, thin hairs | Long fine lines such as rigging, branches and lettering |
| Angle (angular flat) | Flat brush cut on a slant | Curved strokes, corners and edges |
| Mop | Large, soft, rounded head | Wetting paper and laying large watercolour washes |
A beginner can do a great deal with three brushes: a medium round, a larger round or flat for washes, and a small round for detail. You can browse by shape in our round brushes, bright and flat brushes and filbert brushes categories.
Brush sizes and why numbering varies
Most round and filbert brushes are sold by number, from very small sizes such as 000 or 0 up to large sizes in the teens and beyond. Many flat brushes are sized either by number or by the width of the head in millimetres or inches, such as a 25 mm (1 in) flat.
There is no universal standard. As Winsor & Newton's guide to watercolour brush shapes and sizes notes, the same number does not necessarily mean the same size brush in different ranges, and this is especially noticeable between English, French and Japanese sizes. In practice:
- A size 6 round from one maker can be noticeably wider or longer than a size 6 from another.
- Within a single range, a higher number means a bigger brush.
- When buying a replacement, compare head length and width if they are listed, not just the number.
Handle length matters too. Short handles suit close work such as watercolour, while long handles let you stand back from an easel when painting in oil or acrylic.
Natural and synthetic hair
Sable
Sable is soft and springy, holds a lot of colour and keeps a fine point, which is why it is traditionally prized for watercolour rounds. Kolinsky sable is the premium form and is priced accordingly.
Squirrel
Squirrel hair is very soft and holds a great deal of water but does not point as well as sable, so it is mainly used for mops and wash brushes.
Hog bristle
Hog bristle is stiff with naturally split ends (flags) that carry thick paint well. It is the traditional choice for oil, and also works with heavy-body acrylic. Poor-quality hog splays easily and is harder to control.
Synthetic
Synthetic filaments range from very soft to very stiff. Winsor & Newton's guide to brush hair for watercolour explains that soft synthetics work well with watercolour while stiff synthetics work best with oils, and that good synthetics can point and carry colour very well. Synthetics are widely recommended for acrylic because they are durable, easy to clean and cope with acrylic's tendency to dry in the brush. They are also an option for painters who prefer to avoid animal hair.
Which hair for which medium
| Medium | Good choices | Why |
|---|---|---|
| Watercolour | Sable, squirrel, soft synthetic or sable-synthetic blends | Soft hair holds water and releases it evenly; rounds keep a point |
| Gouache | Soft synthetic or sable | Similar handling to watercolour, slightly thicker paint |
| Acrylic | Synthetic (soft or firm); hog for heavy body | Durable, easy to clean; acrylic dries fast and can damage fine natural hair |
| Oil | Hog bristle, firm synthetic; soft sable for glazes and detail | Stiff hair moves thick paint and holds texture |
If you are still choosing a paint, our guide to the differences between acrylic, oil and watercolour explains how each behaves. Keeping separate brushes for watercolour and for acrylic or oil is good practice, because residue from one can affect the other.
Cleaning, care and solvent safety
Water-based paints
For watercolour, rinse in clean water. For acrylic, wash the brush before the paint dries, using lukewarm water and mild soap, working the soap gently into the base of the hairs, then rinse. Dried acrylic in the ferrule (the metal part) is the most common way brushes are ruined.
Oil paint
Wipe off excess paint with a rag, rinse in a solvent or a dedicated brush cleaner, then wash with soap and water. Odourless or low-odour solvents still give off vapour. The HSE's guidance on solvents explains that breathing solvent vapours can cause headaches, dizziness and irritation, and that ventilation is always needed; it also suggests using water-based products where possible.
- Paint in a well-ventilated room and keep solvent jars closed when not in use.
- Wear gloves if your skin reacts, and wash off any spills promptly.
- Rags soaked in drying oils such as linseed can self-heat; lay them flat to dry outdoors or keep them in a sealed metal container before disposal, following your council's advice.
- Do not pour solvents down the sink; let the pigment settle and reuse the clear solvent.
- Keep solvents and cleaning jars away from children and pets.
Soap-style and solvent-free options are in our brush cleaners category.
Drying and storing
- Reshape the head with your fingers while damp.
- Dry brushes flat or hairs-up, never standing on their hairs in a water jar.
- Store dry brushes so the heads are not crushed; a roll or upright holder works well.
Quick summary
- Start with a medium round, a larger round or flat, and a small detail round.
- Match the hair to the medium: soft for watercolour, synthetic for acrylic, stiff for oil.
- Compare actual dimensions; size numbers differ between makers.
- Clean acrylic before it dries and use solvents only with good ventilation.
- Dry brushes flat or upright and keep their tips in shape.
Putting your new brushes to work? Our watercolour painting for beginners guide is a good next step.
Frequently asked questions
What paintbrushes does a beginner need?
Three brushes cover a lot: a medium round, a larger round or flat for washes, and a small round for detail. Add a filbert or fan later if your subjects call for blending or texture.
Why is a size 6 brush different between brands?
There is no universal brush sizing standard, so the same number can mean a different head length and width in different ranges. Compare actual brush dimensions rather than relying on the number.
Which brushes are best for acrylic paint?
Synthetic brushes are widely recommended for acrylic because they are durable and easy to clean; stiff hog bristle also suits heavy-body acrylic. Wash them before the paint dries.
Is sable or synthetic better for watercolour?
Sable holds a lot of colour and keeps a fine point, while squirrel suits mops and washes. Good soft synthetics and sable-synthetic blends also point and carry colour well and cost less.
How should I clean brushes after oil painting?
Wipe off excess paint, rinse in a solvent or dedicated brush cleaner, then wash with soap and water. Work with good ventilation, keep solvent jars closed and never pour solvent down the sink.