Brush cleaning is imperative for painters, and keeping these important tools clean will extend their life and maintain the quality of the marks they produce. This guide sets out some brush cleaning methods for each medium, and gives tips for keeping your brushes in their best condition for longer.
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When cleaning brushes for any medium, you want to return your brush as close to its original state as possible in between painting sessions. Brush cleaners and brush soaps can help do this.
What is Brush Cleaner?
Brush cleaners are designed primarily for brushes used for oil and acrylic paints. They have a strong solvent action (though they are usually solvent-free) that removes wet and dry paint from brushes. For oil painters they are a good alternative to using oil painting solvents, like turpentine or mineral spirits, to clean brushes. Brush cleaners can also be used to remove dry, hardened paint from brushes (I tested that here).
After removing as much paint as possible with a brush cleaner, the brush should be rinsed with brush soap to remove the brush cleaner and any remaining paint residue.
How is Brush Soap Different from Regular Soap?
Many painters find that regular washing up liquid works well to remove paint from their brushes, but specialist brush soaps contain oils, like vegetable or olive oil, that condition the brush while it cleans. A well-conditioned brush will last longer and hold its shape better.
Some brush soaps, like Leonard Clean Brush Black Soap and Speedball Pink Soap, are liquid soaps that can be worked into the brush hairs with the fingers. A silicone brush cleaning egg is also a useful tool for working the soap into the bristles.
Cleaning Oil Painting Brushes (traditional and water-mixable oils)
Oil painting brushes can be synthetic or made with natural hair, often hog hair. Here is a method that we recommend:
1. Remove excess paint from the brush with a rag or a paper towel.
2. Rinse the brush to remove as much paint as you can. There are several things you can use to rinse your oil brushes:
- A brush cleaner like Bristle Magic or Turpenoid
- An oil painting solvent such as turpentine or mineral spirits. Odourless mineral spirits are petroleum distillates that have had aromatic components removed, and many artists find them more pleasant to use in the studio.
- A drying oil like linseed oil or safflower oil. This is also a good way to rinse brushes during a painting session, as the oil in the brush will not affect the painting.
- A non-drying oil such as vegetable oil.
- For water-mixable oils, you can simply use water to rinse the brush. This article contains an in-depth look at cleaning up watermixable oils
Blot the brush with the rag or paper towel and repeat until there is no more paint coming out.
3. When you’ve removed as much paint as you can from the brush, use brush soap to thoroughly wash the brush, cleaning vigorously to ensure that any paint is removed from the base of the brush hairs. When paint dries at the base of the brush, it can cause the brush hairs to splay.
4. Reshape brush with your fingers and allow to dry horizontally on a flat surface.
Recylcing solvent and brush cleaner
Whatever you use to rinse your oil painting brushes, allow the pigment to sink to the bottom of the jar or brush washer and pour off the clean oil, brush cleaner, or solvent into another vessel where it can be used again. The remaining sediment can be wiped away with a cloth, or you can mix it with a painting medium and paint with it. A mixture of pigments usually makes a neutral grey or brown which is great for toning a canvas or painting panel.
Keep in mind that oily rags or paper towels are a fire hazard. As linseed oil oxidises it releases heat, while this is not a concern when the oil is used in a painting, rags and paper towels act as insulators, and the linseed oil can spontaneously combust. Oily paper towels or rags should be kept in a covered, metal can filled with water.
Cleaning Acrylic Painting Brushes (including acrylic inks and acrylic gouache)
1. Rinse the brush with water, and repeat until no more paint comes off the brush when it is blotted. A plastic brush washer is useful for this – the bottom of the pot has ridges that help shift stubborn paint.
2. Use brush soap to thoroughly clean the brush, paying particular attention to the base of the brush hairs where paint and painting mediums can collect.
3. Reshape the brush and leave on a flat surface to dry.
Tips for Looking After Acrylic Paint Brushes
- Because acrylic dries so quickly, clean brushes straightaway after a painting session.
- Avoid leaving brushes to soak for too long in water, as it can bend the bristles.
- Leave to dry flat after cleaning, and store with the bristles up only when dry (so that water doesn’t run into the ferrule and loosen it).
Cleaning Watercolour Brushes (and those used with traditional gouache)
Watercolour brushes are most commonly made from synthetic, sable or squirrel hair. Because they are so soft they require more delicate handling, particularly natural sable and squirrel brushes.
Watercolour brushes can be thoroughly cleaned by removing excess watercolour or gouache with a cloth before rinsing in a jar of water. As with other mediums, blot the brush and rinse until there is no more colour coming out of the brush.
You shouldn’t need to use brush soap after every watercolour painting session. In fact, natural sable and squirrel brushes contain natural oils which can be stripped by frequent cleaning, particularly with regular household dish soap. When you do use brush soap, be sure to rinse it out thoroughly, as any soap product can destroy the sizing of watercolour paper.
Tips for Taking Care of Watercolour Brushes
- Avoid leaving the brush soaking in water. It can crack the handle and loosen the ferrule, and the brush hairs could get bent.
- Some pigments might stain your brush even after thorough cleaning, but this doesn’t affect how the brush can be used.
- Reshape the brush while it is wet. It is normal for natural sable watercolour brushes to splay out slightly when dry, but should come to a point when wet.
Cleaning Drawing Ink Brushes
The best brushes for ink are natural or synthetic watercolour brushes and Chinese brushes. Like watercolour, brushes should be rinsed and blotted until no colour remains in the brush. Brush soap can be used, though many artists do not recommend it for Chinese goat hair brushes because it can affect the absorbency of the hair.
Cleaning Alcohol Ink Brushes
It’s best to use synthetic watercolour brushes with alcohol inks. After a painting session, the brushes can be cleaned with isopropyl alcohol or alcohol ink blending solution. As with other mediums, it’s always recommended to clean the brushes before they have the chance to dry out, but if alcohol ink does dry on the brush, it can be revived by soaking in isopropyl alcohol.
How Do I Dispose of Dirty Painting Water?
The jars of water you use to rinse your watercolour and acrylic brushes shouldn’t be poured down the sink. Allow the pigment to sink to the bottom of the jar. The clean water can then be poured away, and the paint sediment can be wiped away with a rag or a paper towel and disposed of with household waste. Alternatively, you can keep the paint sediment aside and mix it with a medium to make a neutral grey or brown paint.
Can I Restore My Dried Oil and Acrylic Brushes?
It happens to the best of us – you forget to wash a brush and you come back a few days later to find it hard and unusable. Re-soluble mediums, like watercolour, alcohol ink, and traditional gouache can simply be revived with water (or isopropyl alcohol in the case of alcohol ink). But with non-resoluble paints, like oil and acrylic-based paints, the brushes can be treated with a brush cleaner. Some are for acrylic paints specifically, and some are for both oil and acrylic paint.
We found some brushes in the Jackson’s studio that seemed beyond saving. They seemed to have been used with oil paint (though we couldn’t be 100% sure of the medium they had been used with):
I soaked them with Bristle Magic Brush Cleaner for around five hours, before cleaning them with The Masters Brush Soap. The four brushes on the left-hand side of the photograph below regained their softness, although a little paint was still stuck in the hair (another brush cleaning treatment could possibly remove this). The brush on the far right-hand side would not loosen up after being soaked in Bristle Magic, ao I tried Zest It Acrylic Brush Cleaner but had no success. Because I could be certain what kind of paint the brush was used for, it’s hard to know what to use to remove the dry paint. It goes to show that brush cleaners are not a catch-all solution for restoring brushes, but in most cases you can improve the quality of the brush.
Depending on the amount of hard paint trapped in the bristles, brushes may remain misshapen after restoring. However, this doesn’t mean they can’t be used for some interesting mark-making. Old, splayed brushes can be just as useful as new ones!
Every artist has their own method for cleaning their brushes – leave a comment if you’d like to share your own tips.