Congratulations! You have just purchased the expensive varnish brush you have been wanting. Now you're looking forward to using it for the first time. But, before you use it you want to make sure you know how to clean it. And, just as important, you want to know the best way to store it. By following a few simple procedures your brush investment will last for many years. Best of all, your brush will actually perform better with every use. Let's begin with a list of the materials you will need to properly clean and store your new brush. Most of these supplies are probably already on hand; none are expensive. You will need:
Three wide mouth containers with lids, either glass or plastic (we use discarded 2# plastic coffee cans).
Thinner, either mineral spirits/paint thinner (they are the same thing)
Liquid dish washing detergent
Paper grocery bags
Paper shop towels
Paint filters (available from any paint store).
Begin by labeling the lid on each container so you can keep them in order. We used 1, 2 and 3 but the more literate among you might want to use A, B and C. The different colored containers in the following photo add a nice touch but in our case they speak more to inconsistent coffee brand purchases than our intent to color code the containers. Fill each of the three containers with thinner to a depth of two to three inches. As the following photo indicates, these containers have already been used to clean brushes as evidenced by the sludge in the bottom of the first container will lesser amounts of in the second and almost none in the third (more on that later). Note also that the thinner in all three containers is still clean and clear even though we have used it to clean brushes. This illustrates an important fact; thinner does not go bad. There is no need to dispose of the thinner after it has been used to clean your brush. In point of fact, tossing the thinner after using it to clean your brush is unnecessary, costly and wasteful. I will get back to that in a moment.
You are now ready to use your new brush. If you are new to applying varnish with a brush, or you have experienced problems with the technique in the past, you may want to read our article on Applying Varnish With A Brush. Remember to "prime" the brush before use as explained in that article. This will not only make brushing the varnish easier; but, it will also facilitate cleaning. It is important to clean your brush thoroughly after each use. Varnish is a reactive finish; it doesn't dry, it cures in the presence of oxygen.
Begin by working the bristles of the brush in the thinner in the first container . Work the bristles aggressively against the bottom of the container to flush the varnish from the brush. Then, holding the brush in one hand, squeeze the mineral spirits from the brush back into the container.
Repeat the process in the second container. Most of the finish in the brush is removed in the first container as can be seen by the relative amount of sludge in the bottom of that container compared to the others. However, the brush is not clean after the first wash as can be clearly seen by the volume of sludge in the second container. Without the second wash this stuff would still be in the brush where it would cure and harden the brush rendering it useless over time.
Repeat the process one more time in the third container. After squeezing the thinner from the brush at the conclusion of the third wash firmly blot the brush with a clean shop towel in order to remove as much of the remaining thinner from the brush as possible. The very small volume of sludge in the third container is evidence of the fact that virtually all of the varnish was removed in the first two containers.
Again, with reference to the photo, it is very important that you use successive cleaning baths in multiple containers to remove all of the varnish from the reservoir of the brush. Work aggressively—you won't harm the brush. Any varnish left in the brush will cure in the reservoir. This will diminish the ability of the reservoir to hold varnish and will soon destroy the effectiveness of your new brush.
Now, give your brush a bath. The three container wash in thinner has removed nearly all, but not absolutely all of the varnish from your brush. In the next step you will remove all of the remaining varnish along with the remaining thinner used to clean the brush. Just as you want to remove all of the varnish, you also want to remove all of the thinner before you store your brush. The only effective way to do that is to wash the brush with detergent and warm water.
For those of you who have used a shaving brush, the next set of instructions will be easy to visualize. Begin by turning the brush bristles up and gently running warm water through the brush while manipulating the bristles with your fingers. Then squeeze a small amount of liquid dish-washing detergent into the palm of your hand and firmly work the bristles of the brush in a scrubbing motion into the detergent. Your objective is to raise a lather with the bristles. On your first attempt you won't get much lather but in successive washes a frothy lather will appear.
Next, invert the brush in running warm water to thoroughly rinse the detergent and thinner/varnish from the brush. Repeat this process until you obtain a thick, foamy lather of soap bubbles. Expect three or four wash and rinse cycles. Water will not harm your brush; remember, the original owner of these bristles wore them outside in the rain and frequently rolled in the mud.
After the last wash cycle gently shake and then spin the brush to remove as much water as you can. To spin the brush place the handle between your palms and work your hands back and forth in opposition to each other so as to spin the brush. The bristles will splay out—that's fine. We will dress them into proper position for storage in the next step.
Finally, from the paper grocery bag, cut strips twice as wide as the distance from the mid-point of the ferrule to the tip of the bristles. Then, cut the strips into lengths about four (4) times longer than the width of the brush. These will become your storage sleeves.
Next, lay the brush toward one end of one of the pieces of paper with the paper extending about 1/2 to 2/3 the width of the brush beyond the tip of the brush. Then, fold the paper over the brush so that the edges are opposite each other somewhere about mid-ferrule.
Now, fold the short end over so that the first edge of the sleeve is parallel with the edge of the brush & ferrule. You don't want to compress the bristles. You do want to hold them firmly in place so they will dry straight (parallel) with the ferrule. Then, begin warping the brush in the paper sleeve using a rolling/folding motion until the sleeve is firmly in place around the brush with the bristles held in proper position to dry.
Finally, secure the sleeve with a short length of masking tape and hang the brush to dry. That's all there is to it; your prize brush is clean, protected, and formed to dry so that the bristles will be in proper alignment for your next use.
Some final thoughts:
A gray/white sludge will quickly form in the first container. This sludge is the varnish you have cleaned from the brush. The second container should also show some sludge indicating the removal of the last bit of varnish from the brush. The third container should remain virtually free of sludge. If it doesn't you are not cleaning your brushes enough in the first and second containers.
As thinner is used up and/or evaporates from the containers you will replenish it by poring liquid from the higher number container into the adjacent lower number container to restore the original level. The contents of the second container are poured into the first and the contents of the third are poured into the second. You will only add new thinner to the third container. As you pour the thinner from one container to the next filter out the "gunk" and clean the bottom of the containers. Mineral spirits/paint thinner does not go bad. Don't throw it away; allow the paint or varnish to settle out and decant the clean liquid by carefully pouring the thinner off the top and through a paint filter.
The varnish "gunk" should serve an an object lesson. This is what you leave in the brush if you don't follow this procedure. The difference is that when left in the brush and exposed to air it cures into a hard varnish plug that can only be removed with a chemical stripper/brush cleaner. This is why you should clean your brush after each use. If you simply suspend your fine varnish brush in thinner between uses this "gunk" is going to begin to cure in the reservoir of the brush. Once cured it will not be "dissolved" by thinner, nor is it removed in the wash cycles. Clean your brush!
If your brush is stiff when you remove it from the sleeve for for the next use, you are either not getting all of the varnish out of the brush, or you are not properly rinsing the detergent from the brush. Either which way, take more time—you don't want to leave behind either thinner or detergent.
It is normal for your brush to loose some bristles during the first few cleanings. Don't be concerned. In fact, over the first few cleanings your brush will actually become softer and more supple; and, it ability to hold varnish in the reservoir will improve. Your new varnish brush will actually improve with age if you clean and store it properly.