cleaning a spill

[jfoldbar]

i spilt some water in the kitchen a few days ago. so grabbed the dish cloth from the sink, and it was bone dry. so i wet it under the tap first , then wiped up the water. and this made me think.

what is the reason why a dry cloth wont wipe up water, it needs to be wet first?

[Strange]

4 hours ago, jfoldbar said:

what is the reason why a dry cloth wont wipe up water, it needs to be wet first?

What a great question. 

I wonder if it is somehow related to surface tension: the dry fibres not being able to overcome it while the damp fibres can.

Or maybe the stiffness of the dry fibres mean they can't come into such close contact with the liquid (after all, it doesn't apply to a very soft fabric like a tissue). This could be tested by thoroughly scrunching and working the dry cloth first to see if that makes it more able to absorb the water...

[EdEarl]

One could study a cross section of dry cloth as it moves from not touching spilled water until it touches the water and has time to absorb some. For a good view, the camera might run through frames faster than typical videos and looking at the fabric contacting water might be magnified. But a cell phone video might give some info.

[Strange]

The answer here looks plausible: https://physics.stackexchange.com/questions/141278/why-does-a-dish-cloth-absorb-liquid-better-when-it-is-damp

[mistermack]

I'm sure it's surface tension that keeps the water away from the fabric for a period. When you put a dry cloth into water, you can often see little bubbles of air shining on the surface of the cloth, showing that the water isn't in close contact to the cloth.

You could test it, by comparing how pure water mops up, to how water with a bit of detergent mops up. I'm guessing the detergent solution would soak up much quicker.