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Author Topic: What makes varnished surfaces shine?  (Read 4433 times)

Kevin Varley

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What makes varnished surfaces shine?
« on: 19/04/2015 15:00:01 »
Kevin Varley asked the Naked Scientists:
   
What makes gloss varnish glossy or alternatively how does matt varnish become dull?

What do you think?
« Last Edit: 19/04/2015 15:00:01 by _system »


 

Offline Colin2B

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Re: What makes varnished surfaces shine?
« Reply #1 on: 19/04/2015 16:27:26 »
Kevin Varley asked the Naked Scientists:   
What makes gloss varnish glossy or alternatively how does matt varnish become dull?
Surfaces shine because of the light reflected from them. Mirrors, water surfaces etc.
The degree of shine we perceive depends on the light hitting the surface being reflected in, mainly, the same direction. Look at the surface and you will see that it acts like a mirror.
A matt surface has small imperfections that cause the reflected light to go in different directions (called diffusion, or diffuse reflections).
The more diffusion the more matt the surface appears.
 

Offline Thebox

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Re: What makes varnished surfaces shine?
« Reply #2 on: 19/04/2015 18:32:02 »
Kevin Varley asked the Naked Scientists:
   
What makes gloss varnish glossy or alternatively how does matt varnish become dull?

What do you think?


The shiny surface acts like a mirror, and the imagine of a light source can be seen on the surface as a reflection of the source, in essence you are not seeing a shiny surface, you are seeing the reflection image of light source, indirectly viewing the light source.
 

Offline Colin2B

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Re: What makes varnished surfaces shine?
« Reply #3 on: 20/04/2015 00:00:52 »
The shiny surface acts like a mirror, ..
Careful, you will ruin your reputation if you start making sensible posts!
 

Offline jccc

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Re: What makes varnished surfaces shine?
« Reply #4 on: 20/04/2015 03:15:32 »
The shiny surface acts like a mirror, ..
Careful, you will ruin your reputation if you start making sensible posts!

hahahaha, good 1!

look forward for good stuff.
 

Offline evan_au

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Re: What makes varnished surfaces shine?
« Reply #5 on: 20/04/2015 22:52:18 »
In addition to the comments about surface smoothness...

Insulators like varnish (or glass or diamond) reflect light better if there is a sudden change in the speed of light between air and the insulator.
The ratio between the speed of light in a material, and the speed of light in a vacuum is called the refractive index (the refractive index of air is very close 1, ie similar to a vacuum).

If the varnish is covered by a material with an intermediate index of refraction between air and varnish (furniture oil, for example), the change in velocity of light is less sudden, and it can act as an anti-reflective coating, reducing the intensity of the reflection. Binoculars and telescopes often use quite sophisticated anti-reflective coatings.

If a material like furniture oil is strongly tinted, that will also reduce the intensity of the reflection.
 

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Re: What makes varnished surfaces shine?
« Reply #5 on: 20/04/2015 22:52:18 »

 

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