What makes glossy paint glossy ?

[Externet]

Hi. Looking for the glossiest finish spray paint can; buying several brands and trying/comparing would be the only way to judge them; but there is a place that fills spray cans with the paint of customer's choice.

What compound determines gloss, in order to ask for extra of that when filling ? -No clear coats later-

[Greg Boyles]

Paints with large pigment particle sizes have a matt finish while paints with a very small pigment particle size have a glossy finish.

 

If you have a matt finish that you want to make glossy then simply spray a clear varnish over the top of it.

[CaptainPanic]

Hi. Looking for the glossiest finish spray paint can; buying several brands and trying/comparing would be the only way to judge them; but there is a place that fills spray cans with the paint of customer's choice.

What compound determines gloss, in order to ask for extra of that when filling ? -No clear coats later-

I think that the guys in the paint shop will understand if you ask for glossy, especially if they give the consumer a choice.

 

Anyway, the paint you should use also depends on the surface you put it on. So, a very glossy paint like car paint might not be suitable for you. Btw, cars are also painted at least twice: once for color, once for a shiny finish. And often they get a base color first.

 

I think that the glossiness (is that a word?) comes from the surface. If the surface is (on a small scale, but not molecular) very smooth, the light reflects like in a mirror. If the surface is more rough, the reflection is diffuse. The mirror-like reflection is glossy.

Edited July 19, 2011 by CaptainPanic

[Greg Boyles]

I think that the guys in the paint shop will understand if you ask for glossy, especially if they give the consumer a choice.

 

Anyway, the paint you should use also depends on the surface you put it on. So, a very glossy paint like car paint might not be suitable for you. Btw, cars are also painted at least twice: once for color, once for a shiny finish. And often they get a base color first.

 

I think that the glossiness (is that a word?) comes from the surface. If the surface is (on a small scale, but not molecular) very smooth, the light reflects like in a mirror. If the surface is more rough, the reflection is diffuse. The mirror-like reflection is glossy.

 

I.E. The pigment particle size.

[CaptainPanic]

I.E. The pigment particle size.

I'm not a paint expert... But I think you're wrong. I think it's the transparent material around the pigment particles that makes it glossy or not.

 

After all, it's possible to have a transparent paint which is glossy (varnish or lacquer).

 

Wikipedia says the following about 'gloss':

Gloss is an optical property, which is based on the interaction of light with physical characteristics of a surface. It is actually the ability of a surface to reflect light into the specular direction. The factors that affects gloss are the refractive index of the material, the angle of incident light and the surface topography.

Edited July 21, 2011 by CaptainPanic

[swansont]

I'm not a paint expert... But I think you're wrong. I think it's the transparent material around the pigment particles that makes it glossy or not.

 

After all, it's possible to have a transparent paint which is glossy (varnish or lacquer).

 

Wikipedia says the following about 'gloss':

AFAIK this is correct. Gloss refers to a surface that has something closer to specular reflection and matte is more diffuse. But you could also have a different index of refraction, which leads to more (or less) reflection off of the surface, with the remainder of the light being absorbed in the material. So a matte paint might have a lower index of refraction as well.

 

[math]R = {(\frac{n_2-n_1}{n_2+n_1})}^2[/math] (normal incidence; it will be smaller at other angles)

 

For air, n is about 1, so a material with an index of 1.5 reflects about 4%, while for an index of 2 it's 11%

[Greg Boyles]

I'm not a paint expert... But I think you're wrong. I think it's the transparent material around the pigment particles that makes it glossy or not.

 

After all, it's possible to have a transparent paint which is glossy (varnish or lacquer).

 

Wikipedia says the following about 'gloss':

 

 

 

Paint is effectively a clear lacquer with pigment added. If the smooth surface of the lacquer is broken by large pigment particles then the light is scattered from the surface rather than reflected.

 

Analogy.......pebble concrete as opposed to smooth surfaced concrete.

Edited July 25, 2011 by Greg Boyles

[swansont]

Paint is effectively a clear lacquer with pigment added. If the smooth surface of the lacquer is broken by large pigment particles then the light is scattered from the surface rather than reflected.

 

Analogy.......pebble concrete as opposed to smooth surfaced concrete.

 

It's the surface effect that is being discussed, though. If the pigment particles do not break up the surface, does it matter if they are large or small?

[CaptainPanic]

Paint is effectively a clear lacquer with pigment added. If the smooth surface of the lacquer is broken by large pigment particles then the light is scattered from the surface rather than reflected.

 

Analogy.......pebble concrete as opposed to smooth surfaced concrete.

Yes, that I can agree with (sort of).

If your pigment particles are large enough and if your concentration of pigment in lacquer is high enough, the lacquer doesn't fill up the space between the pigment particles anymore, and you have a matte finish.

 

However, I maintain that you can get gloss by simply adding more lacquer - regardless of the pigment particle size. Therefore, I maintain that the particle size has nothing to do with it.

[Greg Boyles]

Yes, that I can agree with (sort of).

If your pigment particles are large enough and if your concentration of pigment in lacquer is high enough, the lacquer doesn't fill up the space between the pigment particles anymore, and you have a matte finish.

 

However, I maintain that you can get gloss by simply adding more lacquer - regardless of the pigment particle size. Therefore, I maintain that the particle size has nothing to do with it.

 

If you run your finger over ceiling paint you can feel the roughness compared to gloss paint. That has nothing to do with refactive index of the lacquer and everything to do with large pigment particles.

 

 

Also if you continually rub ceiling paint with Jiff or what ever, it eventually acquires a sheen. That can only be explained by emergent large pigment particles being worn down to create a smooth finish.

 

Differences in refactive index may account for the difference between gloss and semi-gloss however.

Edited July 26, 2011 by Greg Boyles

[CaptainPanic]

If you run your finger over ceiling paint you can feel the roughness compared to gloss paint. That has nothing to do with refactive index of the lacquer and everything to do with large pigment particles.

 

 

Also if you continually rub ceiling paint with Jiff or what ever, it eventually acquires a sheen. That can only be explained by emergent large pigment particles being worn down to create a smooth finish.

 

Differences in refactive index may account for the difference between gloss and semi-gloss however.

If I bury huge pigment particles under a 1 mm layer of transparent lacquer, it will shine (it'll be glossy)... regardless of the size of those particles.

And if I take tiny pigment particles (smallest possible), but I make the surface rough with some Jiff or sandpaper, it will be matte.

 

Are you denying this, or are we discussing two different things and do we agree with each other?

[Greg Boyles]

If I bury huge pigment particles under a 1 mm layer of transparent lacquer, it will shine (it'll be glossy)... regardless of the size of those particles.

And if I take tiny pigment particles (smallest possible), but I make the surface rough with some Jiff or sandpaper, it will be matte.

 

Happy???

 

However it seems that it is not necessarily pigment particle size that determines the finish and it can be large grain size additives, such as talc, that creates the light scaterring surface of the paint. But the priciple I am enunciating remains sound.

 

PF Online

 

Flatting. In trade sales, as well as many industrial coatings, a variety of additives are used to control gloss. These materials include silica in clear coatings or varnishes and other extender pigments such as clays, talcs and carbonates in pigmented systems. While it is common knowledge that the solid particles or pigments in a given coating must be smaller in diameter than the dried film thickness of the intended coating, many people fail to realize that when using silica to lower gloss, precise particle size control is important.

Edited July 26, 2011 by Greg Boyles

[swansont]

However it seems that it is not necessarily pigment particle size that determines the finish and it can be large grain size additives, such as talc, that creates the light scaterring surface of the paint. But the priciple I am enunciating remains sound.

 

PF Online

I think you wanted to use this link http://www.pfonline.com/articles/the-importance-of-particle-size-in-liquid-coatings

 

If you read the details, they are saying that particle size affects the interaction with the surface, and that smaller particles give a a higher-gloss finish.

 

Finer particle size will yield better quality transparency and gloss due in part to film smoothness.

[Greg Boyles]

I think you wanted to use this link http://www.pfonline....liquid-coatings

 

If you read the details, they are saying that particle size affects the interaction with the surface, and that smaller particles give a a higher-gloss finish.

 

 

 

That is exactly what I have been trying to say through all these posts, i.e. that particle size of the pigment or additive determines whether the finish is matte or glossy and that refractive index of the lacquer has little if anything to do with it.

 

Although I had not considered the possibility of additives determining the finish rather then the pigment particles.

Edited July 26, 2011 by Greg Boyles