Trying to add what would be a tattoo to skin (Tween Ryan 7 Iray). No matter what color I make it, whether it's added to the map file or added as a LIE, it renders red.

Images attached showing it added to both a G3M with Iray G3M Maps/Shaders and G3M with Tween Ryan 7 Maps/Shaders. It's fine on default G3M, but it's red (in the render) with Tween Ryan 7 Maps/Shaders.

Why?

G3M with G3M Shaders on Left, G3M with Tween Ryan 7 Shaders on Right.

If you add it to the base/diffuse colour it's still affected by other contributors to the final colour, most notably in this case SSS. You need to use the same image as a mask on SSS strength or, more simply if you are using Iray with the Iray Uber Base shader, apply your tattoo to Diffuse Overlay

I have a similar problem with an Extreme Makeup kit from Daz, and its actually a bug that it is not applying it to the translucency channel. You can also try that and see if it addresses your issue.

"If you add it to the base/diffuse colour it's still affected by other contributors to the final colour, most notably in this case SSS. You need to use the same image as a mask on SSS strength or, more simply if you are using Iray with the Iray Uber Base shader, apply your tattoo to Diffuse Overlay."

Where is the DiffuseOverlay? There is Diffuse Overlay Color, Diffuse Overlay Roughness, and a few others starting with Diffuse Overlay- none of them are just "Diffuse Overlay". Placing images LIE on any of those changes nothing.

Diffuse Overlay Colour would be the basic one. You'd add the map directly, not via LIE.

This is why I often give up trying to do different things. I went to apply the image to Diffuse Overlay Color - now there's no Diffuse Overlay Color. When I posted yesterday, there was Diffuse Overlay Color on the Face Surface.

I tried adding the image to Diffuse Roughness and Diffuse Overlay Weight - no effect. The image has the tattoo, but it doesn't show up in the preview or render. | AAAAAAAAAAAAAAAAAARRRRRRRRRRGHHHHHHHHHHH!!!!!!!!!!!!

Make sure you have the Iray Uber Base Shader applied, Diffuse Overlay is a property of that.

It is Iray Uber Shader. When I originally posted, I mentioned Diffuse Overlay Color because it was there. Now it's not.

Diffuse Overlay Weight and Diffuse Overlay Roughness are there.

Is the weight greater than 0? That's necessary (and needs a mask map, but presumably you have one from the LIE overlay).

If the weight map is over 0, the skin turns lighter and lighter. At 1, the skin is white.

I have a skin there with the tattoo on the skin- the tattoo is black. It cuts out a section of the white - the shape of the black tattoo.

Looks like another thing I will have to give up trying to do. Something as simple as putting a certain color tattoo on a skin shouldn't be this hard. I don't understand why a black tattoo on skin shows up red in the render, and why a black lie even renders red.

Because of the Translucency channel. You need the tattoo in Translucency Color and possibly a black version of it in the Translucency Weight.

I'm going to give that a try.