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I am trying to create a round cocotte as in the image below.

enter image description here

This cocotte is enamelled cast iron. And my question is about how to recreate the enamelled cast iron in blender.

Traditional enamelling in simple terms is the fusing of tiny glass particles with heat to form a solid layer of colour onto a metal background. It can be matt, shiny, opaque or translucent, and comes in a wide selection of colours and finishes.

I have now a very first model and I am in the process of recreating this enamelled cast iron in blender. I first want to know if this works before I continue.

I have created a mix shader. Mixing a principled shader with the cast iron (including roughness) and a principled shader for the color. This is the result.

enter image description here

As you can see the red colored surface has the same surface structure/roughnes as the cast iron. But that is not what you can see at the image of the real cocotte. That is because the melted glass is a sort of coating on the cast iron. This coating has sort of a smooth, wavy surface.

How to give this red enamelled glass coating the smooth, wavy surface ? I don't think I can do that with changing the roughness of the cast iron. I now think I shouldn't use the cast iron textures. Because the color will always get the surface of the cast iron and that is not what I want.

I think I should create a material that gives that lumpy, wavy surface as you can see in the image of the original cocotte. How to create such a surface ? A sort of wavy, gloopy surface....

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    $\begingroup$ If you are using a principled BSDF you can try to increase the "clearcoat" value. This will add a thin layer of reflection on top of your material $\endgroup$ – Gorgious Jan 22 '20 at 15:21
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Artistic approach using noise and principled bsdf

enter image description here

I'd use a principled shader along with a specular value of 1 and a roughness value of 0.3 to get the surface appearence of iron. You can break the rules and raise up the clearcoat value to 2 or even higher in order to match the shininess/coating of the reference. For each type of surface bump, you can combine different 3d noises and feed them into the normal socket of a principled shader. I'd also add some color variation to the base color using noise again:

enter image description here

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  • $\begingroup$ Your node setup is pretty well doing what i wanted. Thanks!! Especially the surface bumps. Having said that, could you maybe explain a bit more why you mixed noise textures for the color and also the mixing of the small and large features for the bumps. And the function of the color ramp in the mixing. $\endgroup$ – Old Man Jan 24 '20 at 14:40
  • $\begingroup$ Sure. From the tech side of things or an artistic point of view? In general you want variation in all sort of things (color, bump, roughness etc.) to get any sort of realism. Using 3d noise is basically just a shortcut to avoid the hassle preparing a texture, which is a time saver and works in a lot of scenarios. Technically the noise is a black and white texture to either drive the color values or the intensity of the bump (height). I suggest enable node wrangler addon so you can Ctrl+Shift-LMB on any node and see what it does if you haven't already... Something else @OldMan ? $\endgroup$ – brockmann Jan 24 '20 at 15:13
  • $\begingroup$ I did play with your noise setup and now I understand it better. Only thing I do not understand very well is how the color ramp for the small and larger features works. $\endgroup$ – Old Man Jan 25 '20 at 10:39
  • $\begingroup$ Makes it black and white in the first place and bumps up or down the contrast (to either get a smooth or sharper transition), that's it @OldMan $\endgroup$ – brockmann Jan 25 '20 at 12:19
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Just to illustrate Gorgious's point

Clearcoat in Principled BSDF
- adds extra white specular layer on top
- keeps underlying material
- Clearcoat Roughness is adjustable separately

enter image description here

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  • $\begingroup$ Thanks for your answer. But I have edited my question because I think I have asked the wrong question. $\endgroup$ – Old Man Jan 23 '20 at 8:17

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