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Author Topic: Is it possible to produce a non-foamy vanishing spray?  (Read 475 times)

Offline thedoc

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Jon asked the Naked Scientists:
   Hi there, could u please help with a science question. Is it possible to produce a "vanishing spray", as used in soccer games, that does not foam up and is more like a spray paint that vanishes. Thanks.
What do you think?
« Last Edit: 26/05/2016 15:50:01 by _system »


 

Offline chris

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Re: Is it possible to produce a non-foamy vanishing spray?
« Reply #1 on: 26/05/2016 22:18:30 »
I don't really understand this question; what is a vanishing spray?
 

Offline evan_au

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Re: Is it possible to produce a non-foamy vanishing spray?
« Reply #2 on: 27/05/2016 11:30:05 »
Quote
what is a vanishing spray?
It is used by referees to temporarily mark football fields for the duration of one play (perhaps 1 minute).

See: https://en.wikipedia.org/wiki/Vanishing_spray

Quote
a spray paint that vanishes
A spray paint that was highly visible would need a lot of liquid, containing some filler which is highly visible. Paints typically use fillers like titanium dioxide (lead oxide having been banned due to toxicity).

But to get this highly visible filler to become transparent is quite a challenge! And it must not kill the grass, or leave a slippery patch on the grass (that could cause a later accident).

I think the foaminess is the secret to being highly visible when first sprayed, and yet disappearing into a damp spot on the grass in a minute or so. The foam contains very little liquid - it is mostly gas, which dissipates into the atmosphere as the bubbles collapse.
 

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Re: Is it possible to produce a non-foamy vanishing spray?
« Reply #2 on: 27/05/2016 11:30:05 »

 

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