Updated: April 25, 2022
A while back, I encountered an interesting little problem. One of my more complex models required more than 100 different colors or textures. Not an issue in itself, but I soon found myself struggling to remember what material I've applied where. Even if you use color names rather than generic labels, it's still hard figuring the difference between red, firebrick, maroon, crimson, or brown, or the reasons why you'd want to use them with a particular model part or component.
The other imperative driving my decision was the fact I wanted to render my SketchUp model(s) in Kerkythea, and make sure that I could individually select each material separately, and apply the right texture to them, even if they seemingly used the same color codes. The thing is, Kerkythea treats same-name materials as one, and so, even though several components had the same "color", they weren't necessarily the same material. Red plastic and red metal don't behave the same. I think I've found an neat way around this. Let me share.
Unique functional names
Here you go. When you select any one of the existing, default materials in SketchUp, you can use them as the baseline for your own custom materials. For instance, select any which named color, and then click on the +Cube symbol (Create material...). This open a separate window, where you see the material color/texture, name, color picker, and texture and opacity settings.
The idea is to simply save a new material with the color named after the functional part it will be used for. Let's say you want to use yellow for two elements in a car models - headlights and several light indicators inside the cabin. However, while they nominally represent the same hue, they will be made of different materials. Hardened glass for the headlights and plastic for the cabin parts.
Now, save the "new" material, without any modifications, as Headlights. Then, choose the same yellow and create another material, and name this one Light Indicators. You now have two easily identifiable materials in your model, which you can functionally distinguish, even though they may be of similar or even identical hue or texture.
If you ever decide you don't like certain materials, you can always start over. First, select "In Model" from the Materials drop down list. Right-click on any which material and delete it. This will also reset what's applied to your components. Alternatively, click on the Edit tab and make the relevant changes to your stuff. You can use new material names, add textures, change the texture size, make ever so slight hue edits by using the Color Picker sliders (color wheel, RGB, and so forth), and then some.
Ten, fifty, one hundred materials - it makes no difference. You can easily control what goes where. By using functionally named materials, you can work around the complexity of your models and the inherent ambiguity of default colors and textures. Aluminum, Anodized, Textured Steel, and alike probably don't mean much. But if you go for things like top deck, lower deck, hull side, or keel in a ship design, you will have a much easier time remembering what you're doing. You will both have more control over final renders, and be able to to fine-tune the use of materials that reflect the realism of your model.
If you've already figured this out, then this little guide is too obvious. But then, if you haven't, hopefully, the idea will save you some time. I found this method quite useful in preventing a thought divergence and unnecessary administrative burden, especially if you're doing abstract, fun designs, and not necessarily care about the absolute authenticity of materials. Then again, colors don't necessarily reflect the material texture anyway, so the functional names definitely help. Well, that would be all for this time. See you around.