Drying brushes

There are more than a few threads noting certain brushes taking longer than 24 hours to dry, and what may be the best way to store a drying brush - hanging or standing upright on its handle. Can anyone expound on the capillary action or wicking as it pertains to moisture in a drying brush (boar/badger/synthetic)? Does the moisture tend to migrate toward the knot or the tips irregardless of position? I have my suspicions but would like to hear from a more knowledgeable source.

H

Water moves from a wetter area to a dryer area on the bristles, then evaporates into the air, regardless of direction. Capillary action is much stronger than gravity, so it doesn't matter if the bristles are pointing up or down.

My concern is moisture in the base of the knot, afterall, water always runs downhill.

Go West Young Man said:

Water moves from a wetter area to a dryer area on the bristles, then evaporates into the air, regardless of direction. Capillary action is much stronger than gravity, so it doesn't matter if the bristles are pointing up or down.

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+1

Differentiating a bit by bristle type, nylon dries almost instantly because it doesn't really hold it's water that well when squeezed and shook. Badger does a better job of holding onto the water, and a very dense brush can trap water especially well. Boar bristle actually absorb water, so it's not simply trapped water which much evaporate, but also absorbed water. Dense boars take the longest, though some less dense models seem bone dry the following morning with the possible exception of the deepest part of the knot.

All of this is reported as it happens in my bathroom. YMMV, but this is the sense I get from the several brushes I've sampled.

spindlecone said:

My concern is moisture in the base of the knot, afterall, water always runs downhill.

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Hills don't have densely packed fibers to wick the water away. Research the capillary effect.

Capillary action is related to the relative "thiness" or "narrowness" of spaces between surrounding surfaces. You have a lot of such spaces in a bristle brush, so this wicking phenonema can be quite significant, which is why brushes can dry whether in the "up" or "down" position. However, there are constraints and factors like drying surface area, knot density and even shape can affect the rate of drying. In addition, some materials are absorptive of water and do not "release it" as easily as others.

The effect of the density/thickness of the bristle itself? Moisture moving from thinner to thicker or thicker to thinner?

I can imagine moisture naturally gravitating to the tips because they are more loosely arrange and hense have better air circulation about them (=dryer), then again, would the mass/density of the knot naturally attract the moisture?

Hercule said:

The effect of the density/thickness of the bristle itself? Moisture moving from thinner to thicker or thicker to thinner?

I can imagine moisture naturally gravitating to the tips because they are more loosely arrange and hense have better air circulation about them (=dryer), then again, would the mass/density of the knot naturally attract the moisture?

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For water to dry, it needs to be exposed to air, which absorbs this moisture. Thus, density can work against drying process as the water is more tightly "locked" into the bristles. Given the same bristle thickness, a more dense arrangement of bristles will dry more slowly than a less dense one. Capillary action of water in less dense brushes may be lessened but not enough to make a signficant difference for the drying of brushes.

DE Shaver said:

Capillary action of water in less dense brushes may be lessened but not enough to make a signficant difference for the drying of brushes.

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I disagree; from experience, more dense brushes dry more slowly. However, that's an issue of "rate". In both cases, the moisture wicks from wet to dry, regardless of orientation.

Of course all of this is also complicated by soap residue (?).

Hercule said:

Of course all of this is also complicated by soap residue (?).

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Perhaps to an extent; unless you're letting your brush get all crusty and built up w/residue, I don't think it will impede drying.

JPDyson said:

I disagree; from experience, more dense brushes dry more slowly. However, that's an issue of "rate". In both cases, the moisture wicks from wet to dry, regardless of orientation.

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Capillary action is lessened in less dense brushes because the distance between strand lessens the intermolecular forces that drive it. However, if you have inferred that I believe dense brushes dry more quickly, you have inferred incorrectly. Dense brushes do dry more slowly and that's because they tend to keep air from picking up moisture. I merely was pointing out the the capillary action is less strong in less dense brushes.

My experience is that the relative humidity is also a factor, on dryer days my brushes dry faster, on humid days it takes a bit longer. But, I don't care if it takes 24 or 30 hours or a bit longer to dry completely. My travel brushes are always sitting out for three days at least to make sure they are thoroughly dried.
When I am done shaving, I rinse the brush very good, squeeze and shake it out and then brush over a towel. I think all depends on how much water is left in the brush, and the size of the brush - larger brush more water: More water = longer drying time, less water = shorter time.

If you are really concerned hang the brush on a cord over a AC/heat vent...the moving air will really speed drying.

I happen to have a towel bar above my floor vent...and a 3' cord hangs all my brushes about a foot over the vent...they spend most of the day and night gently swinging in the wind (my furnace has a recirculation mode that moves air many hours a day) and I have yet to find one damp the next morning.