Brush 101
Finishing can be a pain in the neck. It’s also scary, since no one wants to ruin the project they put so much work into. While I can’t answer all your finishing questions – or for that matter all of my finishing questions – I want to tell you a bit about the most important part of success for brushed-on finishes: the brush.
Now don’t let all the FUD fool you; brushing is a great way to apply many types of finish, and it’s not a lot more work than most other techniques. Where most people get into trouble when brushing is either rushing successive coats or using a cheap brush. A brush can last for many years if you take good care of it. A good brush will make the finishing an absolute pleasure, and make the finish come out better. Don’t skimp to save a few bucks.
There are three things that make a good brush: long bent bristles, flagged ends, and a fluid reservoir. The picture shows what it would look like if you were to slice a good brush in half.
One of the first things you’ll notice is there’s a gap in middle of the bristles. No, the child laborers in the Indonesian paintbrush factories aren’t smuggling extra bristle material out to pay the rent. Well, maybe they are. But that gap is the fluid reservoir, and it’s where the brush holds the finish before it is delivered to the wood. When you dip the brush into the finish, this reservoir fills with finish. This is what allows you to take long smooth strokes while the finish flows smoothly on to the surface.
If you look a little closer at how the gap is formed, you’ll notice the next aspect of a good brush. The bristles are one long fiber bent in half at the top–not a whole bunch of short fibers stuck together. This prevents the bristles from falling out as you brush on a finish. Tada! No more cursing about those %#@$! bristles stuck in your finish. It also means that your nice brush won’t suffer from premature pattern baldness.
Lastly are the tips of the bristles. Like a professional swimmer’s hair, your brush should have a severe case of split ends–or, in the brush biz, “flagging”. The purpose of flagging is to split all those relatively coarse fibers that make up the brush into thousands of tiny fibers just where they deliver the finish to the wood. This allows a smooth even coat of finish to be spread across the surface.
One last thing about the bristles that throws many folks for a loop – natural vs synthetic bristles. Natural bristles are actually real live animal hair, and are priced and classified by the animal of origin–badger, for example, being the very top of the line. In general, natural brushes are best for oil and solvent based finishes, but they don’t handle water based finishes well. That’s because natural bristles will soak up water from the finish and swell, so when you are dealing with water based finishes use a synthetic brush. They’ll distrube your water-based finishes more smoothly and uniformly, and they’re usually cheaper to boot.
Hopefully this will help you choose a good finishing brush for your next project. Remember that the brush is the last thing to touch the valuable project you worked so hard and so long on, so don’t skimp at the end.
Brian Todoroff
Contributing Editor, Nothing Severed Yet
www.nothingseveredyet.com
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