Creating Porcelain in Cycles

Hey, I am just now learning cycles, and I am trying to create a brown porcelain object (power-line insulator). The object is brown, but the glossy highlights and reflections need to be white. Which nodes should I use? If I use brown for the color in the glossy node, the highlights also come out brown. If I use white, the entire object is white. In either case, both the "mix’ and “add” nodes become pointless. Am I missing something simple? I cannot find any tutorials on this.

Thanx. Dustin

Well, I guess I answered my own question. It seems that the “Glossy” node is almost a purely mirror function—which explains why it was causing my colors to wash-out.

But, that brings up a new question. What node(s) would I need to add, to control the contrast of the reflections? Basically, I want to increase the effect of the specular highlights created by the sunlamp, while reducing the effects of other (darker) environment reflections. Also, is there a node that can control the amount of reflection at different angles, similar to the “fresnel” control in Blender render?

Plug a brown diffuse and a white glossy into a mix node. Then plug the fresnel node into the fac slot of the mix. If you have the shaders the right way round - you should now have a brown material with white glossy highlights. Tweak the IOR of the fresnel node to make the highlights weaker or stronger.

Thanks Moony, that did the trick. It took me a while to find the fresnel shader, though. I had to use the search function, to add it to my node tree.

Just one other question: Is there a way to boost the specular highlights, without increasing the rest of the reflections? In bright sunlight, the specular highlights should be almost blinding.

Yeah, boost the sunlight :slight_smile: I’m actually not kidding, if you use HDRI’s to light your scene, the sun will usually be pretty bright (like, above full white), but not have the actual luminance value. Like, 3 stops are per definition HDR, but you would need a lot more to capture the full brightness. Either edit the HDR or add another lightsource/sun - a point light needs to be far away to cast relatively parallel shadows, a sun light may be hard to position. There are ways to scale the image, but it’s kind of advanced and I’ve seen no approach that cover all HDRI’s.

If looking for a glare effect from bright highlights, you have to do it in post.

You may consider more glossy shaders. Diffuse and rough gloss combo (and very low facing gloss, like, max 4%) should be the base porselain (gloss still white - practically all dielectrics have white gloss in combination with diffuse color, and same amount of bump but I sometimes use less bumps for gloss here). Then mix in another gloss for glazing effect, also controlled with a fresnel like effect, but with sharper highlights. You may want a small amount of bump to shine through here, and/or add low frequency sharp’ish (I always end up in trouble with this one) bump to show some unevenness. This glazing layer could have facing reflections somewhat higher.

OK, I boosted the sunlight, by the equivalent of 4 stops (16x). That cured my balance problem, between the reflections and specular highlights. However, the brown of the porcelain, now looks orange. Is there an intensity node, that I could place between the diffuse node and the mix node—similar to the intensity setting in Blender render?

It’s a rather simple scene, with just a sunlamp and a plain gray background, for testing materials.

Well, i don’t know if this was the right way to do this. But, to compensate for the much brighter sun lamp, I added a second mix node, between the diffuse node and the first mix node—to act as an intensity control. I connected the diffuse output to the bottom input of the mix node, and I left the top input empty (yielding black). The mix output goes to the other mixer, to be combined with the glossy output. A factor of between .06 and .19 seems to bring colors back to where they should be—.06 for the brightest colors and .19 for the darkest colors.

Anyone know a better or more appropriate way? Should I try to post render outputs or a screen shot? I don’t know if I have been on this group long enough, to upload images