Nail polish?

[bitbang]

So I was talking with a guy who does custom lego pieces and figures and he mentioned using nail polish.

My first thought was, wouldn't it chip off too easily!? I didn't have time to talk enough with him as we were in a line...

But has anyone ever used nail polish?

[fred67]

Yes... look at my signature, the yellow eared elves; the picture is a link to the original post. And I know I'm not the only one.

[HawkLord]

I've heard of nail polish being used on action figures to help tighten ball-socket joints. By coating the surface with alittle nail polish, it makes the joints tighter.

Granted this doesn't help the concept of using nail polish on Legos, but it does illustrate that nail polish can be pretty tough.

[ShaydDeGrai]

My first thought was, wouldn't it chip off too easily!?

The primary reason why nail polish chips (when used as originally intended) is because the finish is actually more rigid than the nail itself. Your nails are constantly growing, flexing, stressing under the pressure of your pulse, etc. whereas the coating itself, once it cures, is pretty stiff and brittle and actually bonds to itself better than it bonds to your fingernail, so when when something has to give (say, in response to a jarring impact) it tends to shear off in chips rather than flex or get riddled with tiny cracks.

But has anyone ever used nail polish?

Way back in the days of Man, Myth and Magic, Blackmoor, and the very first editions of D&D, I used to use nail polish to distinguish the +10 values on my 20 sided dice (which where annoying numbered 0 to 9 twice rather than 1-20 as they are more often seen today). It worked great and, since the dice were just as rigid as the finish (if not more so) I never had a problem with chipping even though those guys were routinely being bounded off of table tops and each other.

I've rarely use nail polish on Lego (just because I don't have much cause to do so) so I defer to the minifig customization crowd on specifics, but I see two issues that you should consider:

1) The issue of flexibility - as mentioned above, nail polish is prone to chipping when a rigid coat is applied to a flexible surface. Most LEGO parts are rigid so you're usually safe, but some minifigure hairpieces and accessories are made from a more flexible plastic. The larger the area you're painting and the more flexible the base material, the more likely the polish will eventually flake off. A dab of color here or there will probably be fine though.

2) The interaction of ABS and acetone - ABS is the dominant plastic used in rigid LEGO parts (they also use polycarbonate for the trans-colored bits and I'm not sure what the flexible parts are made from) and acetone is the base solvent used in most nail polish today. When combined, acetone will diffuse into the ABS. In small doses this can be a good thing for a paint job in that the nail polish really can penetrate the surface of the brick and get really good (mechanical) bonding to all the little pits and scratches that are too small for us to see with the naked eye. Over doing it, however, can compromise the material.

Contrary often sighted belief, acetone does not actually break down the chemical structure of the ABS, but instead it permeates the material acting like a lubricant between molecular chains, allowing them to move past one another when faced with external stresses. This makes the ABS structurally weaker, more prone to flexing, twisting and getting squished out of shape. This is a mechanical diffusion process not an aggressive chemical reaction, so it takes time and is a function of the duration of exposure, the concentration of the acetone, the density of the ABS and the surface area exposed to the acetone vapors.

In nail polish, the acetone content is fairly low (or replaced entirely by other chemicals) so you shouldn't have to worry about it "eating" any of your parts, but if you make a mistake and try to correct it with an acetone based nail polish remover you might end up making the part more prone to surface scratching and loss of clutch power in the future. Like damage caused by UV light exposure, it's one of those things that impact how ABS ages even if the immediate changes aren't readily apparent.

[MAB]

There are two uses - as a paint or as a protector.

As a paint is covered above (such as the yellow ears). The other is to use clear nail varnish to protect another deisgn such as a sticker or decal. For this, I prefer a matt spray acrylic varnish. I find nail varnish is too shiny when you compare it to other lego figures.

[bitbang]

The primary reason why nail polish chips (when used as originally intended) is because the finish is actually more rigid than the nail itself. Your nails are constantly growing, flexing, stressing under the pressure of your pulse, etc. whereas the coating itself, once it cures, is pretty stiff and brittle and actually bonds to itself better than it bonds to your fingernail, so when when something has to give (say, in response to a jarring impact) it tends to shear off in chips rather than flex or get riddled with tiny cracks.

Way back in the days of Man, Myth and Magic, Blackmoor, and the very first editions of D&D, I used to use nail polish to distinguish the +10 values on my 20 sided dice (which where annoying numbered 0 to 9 twice rather than 1-20 as they are more often seen today). It worked great and, since the dice were just as rigid as the finish (if not more so) I never had a problem with chipping even though those guys were routinely being bounded off of table tops and each other.

I've rarely use nail polish on Lego (just because I don't have much cause to do so) so I defer to the minifig customization crowd on specifics, but I see two issues that you should consider:

1) The issue of flexibility - as mentioned above, nail polish is prone to chipping when a rigid coat is applied to a flexible surface. Most LEGO parts are rigid so you're usually safe, but some minifigure hairpieces and accessories are made from a more flexible plastic. The larger the area you're painting and the more flexible the base material, the more likely the polish will eventually flake off. A dab of color here or there will probably be fine though.

2) The interaction of ABS and acetone - ABS is the dominant plastic used in rigid LEGO parts (they also use polycarbonate for the trans-colored bits and I'm not sure what the flexible parts are made from) and acetone is the base solvent used in most nail polish today. When combined, acetone will diffuse into the ABS. In small doses this can be a good thing for a paint job in that the nail polish really can penetrate the surface of the brick and get really good (mechanical) bonding to all the little pits and scratches that are too small for us to see with the naked eye. Over doing it, however, can compromise the material.

Contrary often sighted belief, acetone does not actually break down the chemical structure of the ABS, but instead it permeates the material acting like a lubricant between molecular chains, allowing them to move past one another when faced with external stresses. This makes the ABS structurally weaker, more prone to flexing, twisting and getting squished out of shape. This is a mechanical diffusion process not an aggressive chemical reaction, so it takes time and is a function of the duration of exposure, the concentration of the acetone, the density of the ABS and the surface area exposed to the acetone vapors.

In nail polish, the acetone content is fairly low (or replaced entirely by other chemicals) so you shouldn't have to worry about it "eating" any of your parts, but if you make a mistake and try to correct it with an acetone based nail polish remover you might end up making the part more prone to surface scratching and loss of clutch power in the future. Like damage caused by UV light exposure, it's one of those things that impact how ABS ages even if the immediate changes aren't readily apparent.

Thanks for going through this. My girlfriend uses nail polish on her art work (mostly paper) but I never seen her use it on plastic. I guess the cheapy brands are more likely to chip. She uses the $4+ bottles though... I may have to snag some... haha

Yes... look at my signature, the yellow eared elves; the picture is a link to the original post. And I know I'm not the only one.

Awesome! It blended so well too

I've heard of nail polish being used on action figures to help tighten ball-socket joints. By coating the surface with alittle nail polish, it makes the joints tighter.

Granted this doesn't help the concept of using nail polish on Legos, but it does illustrate that nail polish can be pretty tough.

Yeah that makes sense. I know my buddy used nail polish on his car as a temp fix where paint was chipping and it seemed to hold well. That is metal though, not plastic.

There are two uses - as a paint or as a protector.

As a paint is covered above (such as the yellow ears). The other is to use clear nail varnish to protect another deisgn such as a sticker or decal. For this, I prefer a matt spray acrylic varnish. I find nail varnish is too shiny when you compare it to other lego figures.

I have used acrylic paint myself and I find it too thick to work with for small detailing. Yes, some nail polish is super shiny but I don't think they all are like that.

Edited January 7, 2015 by bitbang

[MAB]

Yes, don't use paint-on paint. Acrylic spray gives a much nicer result.

[JakePley]

Ahhh the dreaded Polish Remover of Nail, one of many items in Lord Evil Business' collection!

[bitbang]

Yes, don't use paint-on paint. Acrylic spray gives a much nicer result.

Thanks I will give this a shot. Do you know if they make acrylic paint pens? I was messing around with my girlfriend's nail polish pens (they are used for nail art I guess) and it was amazingly easy to detail small pieces. I used some old bricks I no longer needed and they came out quite well. Gave them a real brick look.