A smooth brushed finish starts with a good brush. And a quality finishing brush can last for years if you take a few minutes to care for it properly after each use.
The temptation after finishing a project is to drop the brush into a container of solvent and deal with it later. But leaving finish buried deep in the bristles can make the brush harder to use the next time — and eventually ruin it.
Fortunately, cleaning a finishing brush doesn't have to be difficult or time-consuming. The process starts before you even open the finish can and ends with storing the brush so the bristles retain their shape.
Match the Brush to the Finish
Before talking about cleaning, it's worth making sure you're using the right brush in the first place.
Finishing brushes fall into two broad categories: natural bristle and synthetic bristle.
Natural-bristle brushes are a good choice for many solvent-based finishes such as varnish, shellac, lacquer, and oil-based paint.
Synthetic-bristle brushes are the better choice for water-based finishes and paints. They can also be used with many solvent-based finishes.
The big limitation is using natural bristles with water-based products. Natural fibers absorb water, causing the bristles to swell and the brush to lose its shape. Synthetic bristles are much less affected by water.
Matching the brush to the finish helps you get better results and extends the useful life of the brush.
RELATED ARTICLE: How to Choose the Right Applicator for Wood Finish
Condition the Brush Before You Start
One of the easiest ways to simplify cleanup happens before you apply any finish. The technique is called pre-loading or conditioning the brush.
Dip the bristles up to the ferrule in the solvent that's appropriate for the finish you're about to use. Depending on the product, that might be mineral spirits, lacquer thinner, alcohol, or water.
Allow the brush to soak for about a minute.
The liquid works its way into the bristles near the ferrule. This helps prevent finish from collecting and drying deep inside this difficult-to-clean area.
Before applying the finish, shake or wipe out as much of the conditioning liquid as possible.
Woodsmith Tip: Keep Finish Out of the Ferrule. The hardest finish to remove is the material that works its way deep into the bristles near the ferrule. Conditioning the brush first and avoiding unnecessarily deep dipping while you work can make cleanup much easier.
Step 1: Remove as Much Finish as Possible
Once you've finished brushing, start cleaning the brush right away.
The less finish you leave in the bristles, the less solvent and effort you'll need during cleanup. Work both sides of the brush against the inside edge of the finishing container, moving from near the ferrule toward the tips.
Continue until you're no longer removing a significant amount of finish.
Don't skip this step and immediately dunk a finish-loaded brush into clean solvent. You'll simply contaminate the solvent faster.
Step 2: Rinse the Brush in the Proper Solvent
Next, rinse the brush thoroughly in a container of the appropriate cleaning liquid.
The same solvent you used to condition the brush can be used for the initial cleaning.
Rather than simply leaving the brush submerged, work the bristles gently against the sides and bottom of the container. This helps the solvent penetrate between the bristles and loosen the finish trapped inside.
As the solvent becomes cloudy with dissolved finish, replace it with clean solvent and continue working the brush.
The goal is to remove finish all the way through the bristle bundle, not just clean the outside.
Woodsmith Tip: Follow the Finish Label. Use the cleaner recommended for the finish you're applying. Don't assume one solvent is appropriate for every product. The manufacturer's cleanup instructions should determine what you use.
Step 3: Remove the Cleaning Solvent
Once the brush is clean, remove as much solvent as possible.
One method is to shake the brush vigorously. Another is to hold the handle between your palms and rapidly roll it back and forth.
This spins moisture out of the bristles.
Do this in an appropriate area where the expelled solvent or water can be safely contained. Wide, flat brush handles may make the spinning method difficult, in which case shaking and blotting the brush is the easier option.
Step 4: Wash the Brush with Soap & Water
For a particularly thorough cleaning, finish by washing the brush with dish soap and warm water.
Wet the bristles, add a little dish soap, and gently work it throughout the brush with your fingers.
A brush comb can also be useful at this stage. Work the comb through the bristles to loosen any remaining finish and straighten the fibers.
After a couple of minutes, rinse the brush thoroughly until the soap and remaining residue are gone.
Even a natural-bristle brush can receive a final water wash. The important part is drying and storing it properly afterward.
Step 5: Reshape and Wrap the Brush
Cleaning isn't quite finished when the brush is clean. The final step is protecting the shape of the bristles while the brush dries and while it's in storage.
Many quality brushes come with a cardboard keeper. Don't throw it away. It's designed to protect the bristles and help the brush maintain its original shape.
If the original keeper is gone, wrap the bristles in heavy paper.
Shape the bristles neatly before wrapping them and store the brush where they won't be crushed or bent.
Leaving a good finishing brush uncovered in a drawer or cabinet makes it much easier for the bristles to become distorted.
Cleaning a Brush Between Coats
If you'll be applying another coat within a relatively short period, you may not need to perform the complete cleaning routine immediately.
The brush can be kept in an appropriate fresh solvent between coats.
When you're finished with the brush for the day, however, give it a thorough cleaning rather than leaving it soaking indefinitely.
A few minutes of maintenance now can save considerably more work the next time you reach for the brush.
How to Rescue a Brush with Dried Finish
Even with the best intentions, sometimes a brush gets forgotten. A brush with partially dried finish doesn't necessarily belong in the trash.
The goal is to soften the dried finish enough to separate and clean the bristles without damaging them.
Soften the Dried Finish
Place the bristles in a mild paint stripper that's appropriate for the finish you're trying to remove.
Allow the brush to soak until the hardened finish begins to soften.
Work Through the Bristles
Once the finish starts to loosen, use a brush comb to gently separate the bristles and work the cleaner farther into the brush.
Alternate between soaking and combing until the bristles become pliable and the dried finish has loosened.
Then complete the cleanup using the appropriate cleaner for the products involved, followed by soap and water when suitable.
Reshape the clean brush and put it back into its keeper before storing it.
Woodsmith Tip: Prevention Is Easier Than Rescue. Restoring a neglected brush takes considerably more time than cleaning one immediately after use. If you've invested in a good finishing brush, make cleanup the final step of every finishing session.
Make a Good Finishing Brush Last
A quality brush is a woodworking tool just like a chisel, plane, or saw. Take care of it and it can serve you through a lot of projects.
The routine is simple: match the brush to the finish, condition it before use, remove excess finish promptly, clean it thoroughly, and store it with the bristles protected.
Once those steps become part of your finishing routine, your brushes will be clean, properly shaped, and ready to go when the next project reaches the finishing bench.
Are You Using the Right Finish Applicator?
A quality brush isn't always the best way to apply a finish. Natural and synthetic brushes, foam brushes, cotton rags, paper shop towels, and finishing pads all have situations where they work best.
CHOOSE THE RIGHT APPLICATOR → How to Choose the Right Applicator for Wood Finish
Stock Your Finishing Cabinet
Brush-cleaning supplies are only part of a well-equipped finishing setup. Our checklist covers 12 essential wood finishing supplies worth keeping on hand, including safety gear, containers, strainers, tape, applicators, solvents, abrasives, and more.
SEE THE 12 FINISHING ESSENTIALS → 12 Must-Have Wood Finishing Supplies
