Wipe the paint off, wash in lukewarm water with a mild soap, reshape the bristles with your fingers, and lay the brush flat to dry. That is the whole method. Everything else on this page is about the mistakes that shorten a brush's life, and one of them is a habit almost every beginner is taught.
Stop standing brushes in a jar of water
You will read everywhere that between colors you should park your brush in a glass of water so the paint does not dry. It is the most repeated piece of brush advice there is, and it does more damage than the dried paint it is meant to prevent.
Two things go wrong. The brush rests on its own bristles at the bottom of the jar, and the bristles take a permanent bend. Synthetic filament in particular does not recover from this, and a bent brush cannot hold an edge. Meanwhile water wicks up into the ferrule, the metal collar holding the hairs, where it swells the wooden handle, cracks the lacquer and softens the glue. That is how a brush starts shedding hairs into your painting six months later.
What to do instead: keep a damp cloth or a wet sponge on the table. Wipe the brush on it between colors, and lay the brush down flat. If you need to leave a brush for a few minutes, rest it in a shallow tray with a quarter inch of water so only the very tips are wet, never the ferrule, and never with the weight of the brush on the bristles.
Acrylic will not harden on a brush in the five minutes it takes to change colors. It hardens over an hour. You have more time than the jar-of-water habit assumes.
Cleaning a brush at the end of a session
Wipe first, wash second
Before any water touches the brush, pull most of the paint out of it with a rag or a paper towel. Pinch the bristles gently between the cloth and draw the brush away from the ferrule toward the tip, never against the grain.
This is partly about the brush and partly about your pipes. Acrylic is liquid plastic, and rinsing a fully loaded brush sends a surprising amount of polymer into the wastewater system. Wiping first means what goes down the drain is a rinse, not a paint pour.
Wash in lukewarm water and a mild soap
Warm, not hot. Hot water softens the glue seating the bristles in the ferrule, and it sets some pigments.
Put a little mild dish soap in your palm, rest the wet bristles on it, and work the brush in small circles against your skin. Your palm is better than any container, because you can feel when the paint has stopped coming out, which is the only reliable signal. Rinse, repeat until the water runs clear, then do it once more. There is almost always more paint in the heel of the brush, where the bristles meet the ferrule, than you think.
Use a mild soap and not much of it. Harsh detergent strips the natural oils from animal-hair brushes and leaves synthetic filament brittle and streaky. Dedicated brush soaps exist and are genuinely better if you own brushes worth protecting, though for the brushes in a paint by numbers kit, dish soap is entirely adequate.
Reshape, then dry flat
Squeeze the water out gently with a cloth, then pull the bristles back into their original shape with your fingertips. A round brush should end in a point, a flat should end in a straight chisel edge. Whatever shape it dries in is the shape it keeps.
Lay it flat, or hang it with the bristles pointing down. Do not stand it upright to dry, because the remaining water runs straight down into the ferrule, which is the one place you do not want it.
The ferrule is where brushes actually die
Almost every ruined brush is ruined in the same half inch. Paint that dries in the heel, where the bristles disappear into the metal, spreads them apart permanently and stops them closing to a point. Water that sits in the same spot loosens the glue.
So the check that matters at the end of a wash is not whether the tip looks clean. It is whether you can feel any stiffness at the base when you press the bristles sideways. If there is any, wash it again now. Once that hardens, it does not come out easily.
Rescuing a brush that has gone hard
Dried acrylic is a plastic film wrapped around each hair. Soap will not shift it, and no amount of scrubbing will either. What does work is a solvent that softens the polymer.
- Isopropyl alcohol, ninety percent or higher. Stand the bristles in a shallow dish of it for five to fifteen minutes, then work the softened paint out with your fingers or an old comb. Repeat if the brush is badly gone. Wash thoroughly with soap and water afterward, because alcohol left in a brush dries the bristles out.
- A dedicated brush restorer. Sold by most art suppliers, slower-acting and gentler than alcohol, and the better choice for an expensive brush.
One caution worth stating plainly, because the same advice given in a different context is wrong. Alcohol dissolving acrylic is exactly what you want on a brush and exactly what you do not want on a finished painting. Never use it to clean a canvas you have painted, because it will lift the paint straight off.
What not to reach for: acetone and nail polish remover. They will soften the paint, and they will also dissolve the adhesive in the ferrule and attack synthetic filament. You end up with a clean brush that sheds hairs and a handle that has lost its finish.
And an honest note: a brush that dried solid weeks ago, splayed like the one above, is usually finished. You can often make it usable for background work, but it will not come back to a point. It is worth ten minutes and not an afternoon.
Storing them
Only store brushes completely dry. A damp brush in a closed case grows mildew, and the smell does not come out.
Once dry, upright in a jar with the bristles pointing up is fine, and so is flat in a drawer. The only arrangement to avoid is anything that puts weight on the bristles. A roll-up case or a rigid box is worth having if you carry brushes around, mostly because loose brushes in a bag get their tips crushed.
Paint by numbers brushes specifically
The brushes that come in a paint by numbers kit are working tools rather than heirlooms, and the same routine applies to them. Two things are worth knowing.
The fine-detail brush is the one that suffers, because it goes into the smallest sections with the least paint and gets pressed hard against the canvas. Wash it first, while you still have patience, and reshape the point every time.
Being straightforward about our own kits: they include brushes in a range of sizes, and readers do tell us the finest brush is coarser than they would like for the smallest sections. Some people keep a good size 0 round of their own alongside the kit for that reason, and we would rather say so than pretend otherwise. If you want more on the small ones, we have a separate guide to cleaning fine-tip brushes.
Common questions
Can I use hair conditioner on paint brushes?
Yes, and it works. A small amount worked through clean, damp bristles and rinsed out softens hair that has gone stiff from repeated washing. It is not a substitute for cleaning, and it will do nothing at all to dried paint.
How often should I deep clean?
Wash properly after every session. Beyond that, a brush only needs a restorer when it stops holding its shape, which for a well-treated brush is rarely.
Is it safe to rinse acrylic paint down the sink?
Small residue from a wiped brush is what domestic drains are designed for. What you should not do is pour leftover paint or rinse a fully loaded brush. Wipe unused paint into a paper towel and bin it, and let the water from a rinse jar settle so you can pour off the clear water and throw away the sludge.
Why does my brush leave streaks after cleaning?
Usually dried paint still in the heel, splaying the bristles. Occasionally soap residue. Wash again, rinse longer than feels necessary, and reshape while wet.
The bristles fan out and will not point. Can that be fixed?
Sometimes. Wash it thoroughly, reshape the tip while wet, and let it dry lying flat. If it still fans, the splay is set from the heel and the brush has reached the end of its useful life for detail work. Keep it for backgrounds and dry-brush texture, where a ragged tip is an advantage.
