Default Mat, Color Mats, Texture Mats along with UV mapping is pretty much an abandoned topic for SU folks, unfortunatelly, though it’s probably one of the most interesting for hooking people to sketchup.
Default material has no UV and neither colored materials. Colored materials also shade different from texture materials of the same color.
The “technique” Tomasz describes is a VERY useful one:
1 - make a component;
2 - edit it and paint it’s faces with a textured material (so UVs can be defined);
3 - position the textures on the face (so UVs are correctly configured);
4 - erase the material from the model;
5 - close the component edition and paint with any textured map;
6 - the material will be following the UVs set in 3.
7 - However, renderers cannot read it…
Here’s a gif of the setup:
Here’s a gif of the render of the output: