Acrylic, Oil, and Watercolor Brushes

Brushes carry our paint from the palette to the canvas. They give us control over our marks and assist us in handling paint and mediums. Therefore, brushes are an important tool for any painter and worth looking into deeper. At GOLDEN, we produce paint in three different mediums: oils, acrylics, and watercolors. Not every brush is suited for every medium, though. Here we want to explore which brush types are best suited for the respective mediums.

We will talk about:

1. Parts of a brush
2. Desired features of a brush
3. Our brush recommendations for watercolor, acrylic and oil painting
4. Pros and cons of natural and synthetic hair
5. Natural brush head materials
6. Synthetic hairs 
7. Brush care

 

1. Parts of a Brush

Let’s start with the parts of a brush. Understanding how a brush is constructed informs us about its quality, durability, and important aspects of brush care. The length of the brush handle varies for different uses. Most watercolor brushes have short handles because watercolorists usually paint small scale and sit right in front of their work, while oil and acrylic brushes can have either short or long handles, so that one can stand back a step while painting and keep an overview of the entire composition. The ferrule secures the brush hair at the hair’s heel to the handle and the more crimps a ferrule has, the sturdier its construction. Inside the ferrule, the brush hairs are glued together into a bundle with vinyl or epoxy resin adhesive. The brush hairs or bristles constitute the head or tuft of the brush, which has a belly in the middle and a tip. The hairs in the tip are the longest and must be particularly strong.

 

2. Desired Features of a Brush

There are some features that are desirable for any paintbrush, regardless of the type of paint one chooses. A brush should:

• Maintain its performance and retain its shape despite daily use.
• Have good paint holding capacity and paint release.
• Have elastic and strong hairs/fibers/bristles, a quality referred to as spring or snap.
• Be responsive to our hand, technique, and to the surface it touches.
• Be chemically resistant, to allow for cleaning with solvents.

A reliable way to assess the quality of a brush, especially when purchasing a costly sable brush, is to rinse the brush in water to remove the stiffening size. When bending the hairs, they should always spring back into position and recover their original shape.

 

3. Our Brush Recommendations for Watercolor, Acrylic and Oil Painting

As a rule of thumb, we recommend having dedicated brushes for each painting medium. If switching between mediums, the brushes may not last as long and tend to lose their desired qualities. A watercolor brush, for instance, once used with oil or acrylics, will usually not perform as desired anymore for watercolor painting.

• Watercolor brushes: Good quality synthetic brushes are fine for water coloring, but they are not equivalent to good quality natural hair brushes in terms of paint control, especially in the way they release paint. Synthetic brushes tend to absorb less water, which can make watercolor gather excessively at the tip and run quickly off the brush, onto a more absorbent paper surface (Image 2). There are big quality differences among natural hair brushes, with Kolinsky sable brushes being the crème de la crème. There are also good blends of synthetic and natural fibers. Generally, a good synthetic filament is better than a poor quality red sable.

 

• Acrylic brushes: For acrylic painters we recommend using synthetic brushes, particularly due to their chemical resistance. Acrylic dispersion paints have a high pH and the alkalinity damages natural hair, which makes them break easier. Acrylic dispersion paints also contain ingredients that strip natural hair of its natural oils, causing the hair to become brittle. Thicker paint like Heavy Body can be easier to manipulate with stiff polyester brushes that have a good snap (i.e. stiff but elastic), while smooth applications with Fluid, High Flow and the relatively soft bodied OPEN Acrylics can be easier to achieve with soft nylon brushes.

 

• Oil brushes: Both natural and synthetic brushes can be used for oil painting. Natural hog bristle brushes are great because they have good stiffness and can hold more paint than synthetic brushes could. Thus one brush load of paint goes a longer way and one is not required to pick up more paint all the time. Especially thicker impasto painting requires stiffer bristle brushes. For fine details and glazes, red sable brushes or soft synthetic hair brushes with good spring are great.

Recommendations for varnishing brushes can be found here.

 

4. Pros and Cons of Natural and Synthetic Hair

Both synthetic and natural hair have their advantages and disadvantages. Where natural hair brushes excel is in their capacity to hold water and paint and in the evenness of the paint release. However, natural hair tends to break easier and could leave hairs behind on the painting, which is called shedding. Albeit poorly made, synthetic brushes might also shed hairs if the hairs no longer hold fast in the ferrule. Natural hair brushes also tend to be more expensive than their synthetic imitations. Synthetic hair brushes have greater chemical resistance and are therefore more suitable for acrylic dispersion paints, which have an alkaline pH due to the ammonia pH buffer. They also work well for varnishes and lacquers that require strong solvents for brush cleaning. Synthetic hair is slicker, which reduces its ability to hold paint and may not deliver the same painting experience as the ‘real’ thing. To get the best of both worlds, one can try blends of natural and synthetic hairs. Last but not least, there is the ethical issue of using animal hair brushes. Animals used for paintbrushes suffer in many of the same ways as animals used for fur coats and the vast majority of brush hair comes from China and Russia, where laws to protect animals are either nonexistent or unenforced. Synthetic hair brushes are thus a cruelty-free alternative.

 

5. Natural Brush Head Materials

The fascinating thing about natural hair brushes is the uniqueness of each hair type depending on its origin. Nothing could ever compare to the ingenuity, uniqueness and intricacy with which Mother Nature equips animals in their furs.

Sable hair

Sable brushes can be made from the hair of weasels, minks, ermines, martens, or kolinskies. Natural sable imitations, often labelled sabeline, can be made of squirrel, dyed ox hair, Russian fitch hair, goat, badger, or American skunk. The finest and most precious of all sable brushes are made from the Siberian kolinsky, particularly from guard hairs from the tail of male winter pelts. These animals do not fair well in captivity and it’s only the wild ones which produce the longest and thickest hairs, needed to survive the Russian winters.

The anatomy of the sable hair is fascinating. It has a flowing curved shape with a thick belly and a very fine tip. In a paint brush, the ferrule holds the hairs just below the belly, which allows for maximum elasticity and snap. This belly helps push the hairs apart in the brush, which opens gaps for water to cling to the hairs. The curve of the hair gives sable brushes, furthermore, exceptional ability to be finely shaped. The surface of sable hair is covered in microscopic scales, the so called spinous cuticle scales that are formed like petals and oriented towards the hair tip. These scales allow sable hair to absorb and hold a lot of water or paint.

Hog bristles

The difference between hair and bristle is that the ends of bristles split up into a handful of tips, the so-called flag, while hairs have a single tip. Bristles have a natural curve, which is reduced somewhat by boiling. This curve is taken advantage of by interlocking fibers during assembly, so that the curved bristles oppose one another and curve towards the center. Domesticated pigs have less bristles and their bristles have less flag. Today’s bristles come mainly from Chinese hogs and the best quality ones come from their neck and along their spine. The surface of hog bristles is covered in so-called imbricate scales, which consists of overlapping scales with narrow margins, also commonly found in human hairs.

 

 

 

 

 

 

 

 

 

Ox hair

Cow or ox hair is taken from the ears (auricles) of the cattle. These hairs are cylindrically shaped and don’t form a fine point like sable hair does. Ox hair is very long, strong, inexpensive, and has appealing elasticity, which makes it great for rougher brush techniques. Ox hair is often blended with hog bristles or inexpensive sable, to give the ox hair brush heads better pointing capability.

Squirrel

Hair from squirrel tails is called Fehair. It is very fine, soft, absorbent, and not springy, making it suitable for the production of mops, flats, filberts, and wash brushes, which must hold a lot of water.

 

6. Synthetic Hairs

The imitation of natural hair with synthetic filaments, particularly nylon and polyester, is a growing and fast developing field as natural hair is becoming scarcer. Challenges are the topography of fiber surfaces and the shape of fibers. Improvements have been made to increase their capacity to carry more water and paint by roughening the hair’s surface, although synthetics still don’t equal natural hair’s load holding capacity. In comparison to natural hair, synthetic hairs are much straighter in form, which doesn’t open gaps so the bundle of hairs holds less water and might release it differently. For bristle imitations, the ends are mechanically tipped to reproduce the flag. With fine hair imitations, fibers are tapered, which makes these synthetics retain their shape better. Filament surfaces are often roughened by abrasion, or etching to increase paint-carrying ability and are additionally dyed and baked to make them softer and more absorbent.

The most common type of polyester used for brushes is PBT (polybutylene terephthalate), which offers many of the same properties as nylon, but absorbs less water. This allows PBT to hold its stiffness in wet applications. Nylon/polyester blends combine the positive qualities of nylon, which is precise tipping, excellent paint pickup, and smooth finish and of polyester, which is added stiffness and control.

7. Brush Care

It’s never good to let brushes soak in water or solvents, as that will make the bristles lose their shape, the ferrules can come lose and in the case of harsh solvents, it can dissolve the adhesive within the ferrule, which is gluing the hairs together.

Watercolor brushes are best cleaned by rinsing in plenty of water, although some staining colors such as Phthalos might require some mild soap to clean completely. Be sure to be gentle with any cleaning and rinse all of the soap from the brush before painting. Allow the watercolor brushes to dry with nothing touching the tip and if the handle is wood, avoid letting the brush dry upright, as that might encourage water to drain into the wood, swell it and ultimately, make the ferrule come lose. It helps to clean acrylic brushes with soap from time to time and to brush out paint that has collected at the heel of the brush with a dedicated nail scrubber. For “heeled up” brushes with dried paint in the hairs, products such as the Masters Brush Cleaner can be great. Oil brushes should be wiped clean as much as possible with cotton rags or paper towels and then cleaned with mineral spirits or with drying oil such as linseed, as described in Cleaning Brushes Without Solvents. When using linseed oil for brush cleaning, the brushes have to be cleaned additionally with a mild soap and lukewarm water after the painting session. Using oil to clean brushes is an aged-old technique and the dirty oil, which one ends up with, has the perfect soupy-brown color for creating colored oil grounds or painting the imprimatura. It is important that the brushes are never exposed to solvents for too long, as the adhesive used to bundle hairs/bristles in the ferrule, can be sensitive to strong aromatic solvents. When storing away natural hair brushes for longer periods, place mothballs nearby.