02-16-2013, 03:24 PM
#1
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Since this is a perennial topic that is quite easily tested (yet for some reason no one ever actually bothers to), I went ahead and did it.

Hypothesis: They'll dry at the same rate

The Subjects: 2x of the same synthetic knot set in the same handle, but one handle was filled with 2 pennies to bring the loft up a little.

Methodology:
Measure weight before saturation.
Dip both brushes in water.
Shake out excess water to approximately the same dryness level. In other words, as closely as humanly possible.
Measure weight after saturation.
Set one brush in drip stand, set other brush base down.
Measure water by weight and feel at intervals.

Methodology discussion:
Obviously not a purely scientific test as I could have used the exact same volume of water and dripped it into the brush (I suppose I could as I have eye droppers). Also, my weight is limited by the sensitivity of the scale used. I do not possess a grain scale that goes up to 90 grams. At least I don't think mine does. I'm fairly certain it only goes to 50. Either case, not very accurate measurements.

Results:
Shortcomings aside, I think the results are pretty clear and the different water removal rates are large enough for my not so sensitive scale and my hands to differentiate.

Totally dry:
BU (bottom up): 86
BD (bottom down): 81

Full saturation:
BU: 88 grams
BD: 83 grams

After 1:40 minutes of drying:
BU: 87.5 g
BD: 82 g

After 2:25
BU: 87.5 g
BD: 81.5 g

After 3:07
BU: 87 g
BD: 81 g

At the last measurement stage, the BU knot was dry at the tips, but noticeably wet in the middle. The BD knot was completely dry. Both in terms of water weight and in feel. Even deep down in the knot to the glue bump.

At that point, I stopped the test.

Conclusion:
Bottom down is clearly faster.

I surmise that evaporation has much more to do with brush drying than gravity. By blocking the obvious route for water to escape, using a drip stand actually inhibits water loss.

I would further surmise that if both brushes started dripping wet, the drip stand may in fact dry faster as bottom down would pool the water at the base, whereas the drip stand would let the larger water droplets drip down via gravity.

However, when talking about water that is not in volumes great enough to actually be pulled down by gravity, evaporation seems to be the main source of water removal. Inhibiting the exit via vertical escape seems to actually severely compromise a brush's ability to dry quickly.




If anyone wishes to replicate the experiment, I am more than willing to lend the brushes.

I do plan to try the experiment one more time using the new WSP boar brushes since everyone agrees that boar absorbs a lot of water and I would have identical subjects.

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 02-16-2013, 03:46 PM
#2
  • Shaun
  • Senior Member
  • St Peters, NSW, Australia
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Fascinating study; brilliantly simple. I don't have scales sensitive enough or two of the same brushes, otherwise I would try the same experiment.

Not sure the last reading is right, though Lee Smile

I look forward to the next instalment using boar.

Unless these things are tested like this, an up/down held view would remain largely subjective/conjectural.

I wonder if 'standing evaporation' means some of the water particles simply rise into the bristles of an upside-down brush? Or they have less chance of 'sublimating off' at the denser base of the knot?

Perhaps the next phase would be to use a light fan blowing air steadily across the bristles so that 'vertical rise' can be factored out? Perhaps that's just getting carried away Smile

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 02-16-2013, 03:48 PM
#3
  • ben74
  • Administrator
  • Perth, Australia
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Great experiment Lee!

Prescribing to the capillary effect, I've always been a BD guy! Biggrin

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 02-16-2013, 03:51 PM
#4
  • Kavik79
  • Active Member
  • Albany, NY - USA
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I've always thought tips up seems to work better, but never ran any actual tests on it. Interesting stuff, I'd love to hear how/if the results would differ with boar and badger if/when you get around to it Biggrin

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 02-16-2013, 04:02 PM
#5
  • ajc347
  • Senior Member
  • Exeter, UK
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Brilliant experiment Lee. Smile

I only use a drip stand on wooden handled brushes as I presumed that gravity would help clear any water away from the handle - it looks like I need to reconsider this in light of your results.

Thanks for posting your results up mate.

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 02-16-2013, 04:06 PM
#6
  • vpayne
  • Active Member
  • Missouri
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That answers that question. Been curious, but not enough to actually do the test.
Thanks, now I know for sure.

Vic

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 02-16-2013, 04:08 PM
#7
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(02-16-2013, 03:46 PM)Shaun Wrote: Not sure the last reading is right, though Lee Smile

Doh! Fixed.

Quote:I look forward to the next instalment using boar.

I'll get it done once the boar brushes come in.


Quote:I wonder if 'standing evaporation' means some of the water particles simply rise into the bristles of an upside-down brush? Or they have less chance of 'sublimating off' at the denser base of the knot?

I theorize that the handle blocks the natural path of evaporation.

Quote:Perhaps the next phase would be to use a light fan blowing air steadily across the bristles so that 'vertical rise' can be factored out? Perhaps that's just getting carried away Smile

Actually a fan blowing on brushes dries them out extremely quickly. The process is so rapid that it's rather hard to measure the effects.

For example: boar will dry out in 2 hours on speed three of a Honeywell tabletop fan. Pretty darn quick stuff.

I theorize that with a fan providing the agitation to the air, either BU or BD will work equally well since the fan is powering the drying, not gravity or evaporation. So, it's kind of a moot experiment in my estimation.

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 02-16-2013, 04:24 PM
#8
  • daccpa
  • Weber fanboy
  • Middle Tennessee
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An interesting side note here, I had been hanging my brushes on a drip stand bristles down and began to notice that they were beginning to smell a little soured. After changing to bristles up drying the smell has disappeared. Didn't notice any significant difference in drying time since I usually always found them dry either way between my daily shaves.

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 02-16-2013, 04:25 PM
#9
  • tgutc
  • Senior Member
  • Michigan
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That's very interesting thank you for posting.

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 02-16-2013, 04:43 PM
#10
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Great stuff Lee!

I work with Greenhouses. Glass greenhouses when they have no plants in them leak air like a sieve. When you start watering plants in them the condensate gets trapped between the glass panes where they overlap. Gravity does NOT EVER pull the water from between the laps. It is not as strong as the capillary action(osmosis) holding the water in place. The water leaves when you remove the plants and quid adding moisture to the house by DRYING OUT. It NEVER runs out from between the panes.
For me common sense(based on my experience) tells me pretty much what you are finding through experiment.

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 02-16-2013, 05:51 PM
#11
  • Kavik79
  • Active Member
  • Albany, NY - USA
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I'd like to point out one other thing that I never hear mentioned in these discussions: centrifugal force.

When you shake out your brush, the force applied that throws all the water out well outweighs the force of gravity (ever notice how the water flies up just as much as it flies down?)

Any water left between the bristles after that isn't likely to be much effected simply by being hung upside down

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 02-16-2013, 07:09 PM
#12
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(02-16-2013, 05:51 PM)Kavik79 Wrote: I'd like to point out one other thing that I never hear mentioned in these discussions: centrifugal force.

When you shake out your brush, the force applied that throws all the water out well outweighs the force of gravity (ever notice how the water flies up just as much as it flies down?)

Any water left between the bristles after that isn't likely to be much effected simply by being hung upside down

Yes, hence my conclusion that the drip method might work better if there were noticeable drops of water that actually dripped out. But since that's obviously very bad for brushes and easily remedied, I'm not going to conduct such an experiment.

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 02-16-2013, 07:55 PM
#13
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Thanks for doing the test.

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 02-16-2013, 09:04 PM
#14
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Thanks for taking the time to perform the test Lee. I always dry my brushes sitting on their base, rarely hanging in a stand. Capillary action/evaporation FTW.

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 02-16-2013, 10:14 PM
#15
  • vuk
  • Senior Member
  • Virginia
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Interesting experiment and thanks for taking to time to perform & report it. I wonder if the heavier BU brush that I assume had the pennies would have retained even more water without the benefit of extra ~3mm in loft.
I use a stand as a means to tidy up the counter but never noticed much difference in drying either way.

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 02-16-2013, 10:16 PM
#16
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So Matt sent back a Prince Finest that had a crack in the handle that he was testing. I realized I had two Prince in Finest, so I started up another round of testing.

Right now they're dead even. Any weight difference is clearly due to my scale's sensitivity not picking it up.

Sadly, I'm probably going to retire for the night before they dry completely so the test will have to be repeated at a later date.

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 02-16-2013, 10:19 PM
#17
  • Songwind
  • Soap Slinger & Scuttle Pusher
  • Burnsville, MN
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Very interesting. Yay, empirical evidence and experimentation.


(02-16-2013, 05:51 PM)Kavik79 Wrote: I'd like to point out one other thing that I never hear mentioned in these discussions: centrifugal force.

When you shake out your brush, the force applied that throws all the water out well outweighs the force of gravity (ever notice how the water flies up just as much as it flies down?)

Perhaps what we really need is a brush centrifuge!

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 02-16-2013, 10:37 PM
#18
  • Kavik79
  • Active Member
  • Albany, NY - USA
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(02-16-2013, 10:19 PM)Songwind Wrote: Perhaps what we really need is a brush centrifuge!

LOL now we're talking! With an open top so there's nice air movement. The benefits of centrifugal force and fan drying all in one! 24

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 02-16-2013, 11:03 PM
#19
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(02-16-2013, 10:37 PM)Kavik79 Wrote:
(02-16-2013, 10:19 PM)Songwind Wrote: Perhaps what we really need is a brush centrifuge!

LOL now we're talking! With an open top so there's nice air movement. The benefits of centrifugal force and fan drying all in one! 24

I'm on it! Cool

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 02-17-2013, 12:08 AM
#20
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Biggrin

FWIW, you do NOT want to put your brush in a centrifuge! Unless you want to re-assemble the brush every day.

Wink OMG! I could envision a CAD in shave nooks... not the best thing for a brush by a long shot.

Just too funny!

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