Ciao, I'm pretty sure
is what you're after. It's not really fully what you mean but then, nothing is. Normally we just use Italian words, in this sort of situation. :)
By the way it's easy to see examples of materico, superficially meaning "paintings with ridges and bumps..."
Just google "Materico" and click "images" for 100s of examples:
I'm not really sure if "impasto" has the same sense of "those paintings with ridges and bumps".
For example, Van Gogh's most impasto pictures ... did they have that materico look? Would you use the word "materico"? I don't know.
Silvia, here's the problem you face:
Imagine a SPECTRUM:
On the left, you have completely physical terms.
But. Moving along, we have terms that are more conceptual.
WTF this Caravaggio dude has chiaroscuro locked-down
it's very plastic (in the sense of "3D ish")
these naive painters are fun
check out the repoussieoire on that
And then. Moving right along, you have totally artistic terms...
Here's the problem you face Silvia....
Superficially, materico just means "impasto" ("thick paint") or "mixed media". So there you go; impasto is the translation to a, uh, English word.
because you're Italian, everything gets elevated two levels. This is exactly why it's so hard to, really, translate Italian (especially if you work with product names or the like). Indeed this is why basically for people from Anglophone regions, the best way to deal with high Italian language is just go to, say, Cremona, forget about everything, and constantly eat and drink. Yeah!
Here's the excellent example I always give of this. There's a car manufacturer in Italy who has a model called the quattroporte. Now for rich car buyers in English speaking countries, Asia, etc, this is the most exotic thing you can hear. The word conjures up fabulous wealths of meaning - style, speed on the sophisticated side, a certain manner of living...
Of course, the word simply means "four door". It's a "four door car". A similar older example from the auto world is simply "testarossa. It just means nothigng more than "red head". There was a bit of red paint on the plastic head covers of the engine! But, in Italian, these words feel, and indeed mean, tremendously more.
I feel, from my limited experience of hearing it used, materico means more than "thick paint". You probably use it, even, to describe images (perhaps even just photographs) that really go "in and out" (for want of a better description).