The point here, I think, is that although "grabado matérico" is a term used in other meanings, which might apply to relief or mixed-media printmaking in other cases, is being used here in a particular sense (adding materials to the plate), specifically associated with the work of Juan Ripollés. It is clear that in coining this term to apply to the kind of printmaking he was doing, Ripollés was thinking of an analogy with the technique known as "matiérisme" in French, one of the greatest exponents of which is Antoni Tàpies. It's known as "pittura materica" in Italian and "pintura matérica" in Spanish, and is normally called "matter painting" in English. It's unmistakable: there's stuff stuck to the surface:

http://fr.wikipedia.org/wiki/Matiérisme

http://www.proz.com/kudoz/italian_to_english/art_arts_crafts...

"Antoni Tàpies’s matter paintings are characterized by thick and highly textured paint layers made of sand or crushed marble mixed with oil-based alkyd varnish."
http://academia.edu/856683/2002._Cracking_the_matter_paintin...

I think this conscious allusion should be maintained, and that the technique should by analogy be called "matter printmaking", the results of which are "matter prints". "Grabado" in Spanish is not just engraving; it covers a wide range of techniques known in English as printmaking.

"Matter print" is how the IVAM translators (who are generally very good) handled it in this catalogue of a Ripollés show.

'el concepto que el mismo artista acuña como "grabado matérico"' (p. 566 (568) para. 3)
'the concept which the artist described as the "matter print"'
http://www.ivam.es/catalogopdf/0494/pdf/Ripolles.pdf


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Note added at 40 mins (2013-07-06 11:36:25 GMT)
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By the way, as far as I can tell from the description and from stuff I've read on Ripollés, these are not engravings.

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Note added at 41 mins (2013-07-06 11:38:01 GMT)
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Nor etchings, for that matter.

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Note added at 48 mins (2013-07-06 11:44:28 GMT)
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By the way (again), although you find the term "materic painting" in some places, I've never been convinced by "materic", which is obviously a calque, and it's not widely used. Nor is "material painting" really suitable, IMO. I do quite a lot of art catalogues and "matter painting" is definitely the standard term, in my experience.

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Note added at 53 mins (2013-07-06 11:50:10 GMT)
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Taña's references certainly suggest that "grabado matérico" can apply to what we call relief printmaking, but from your description (which does sound a lot like Ripollés or someone working in the same way), it doesn't mean that here.

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Note added at 2 days2 hrs (2013-07-08 13:39:24 GMT) Post-grading
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Hi Neil,
You're lucky to have such an expert advisor, and it's lucky for me too, because I've learnt something very useful here. I should have known about collagraphy, and didn't, so I'm very grateful for that. I completely agree that "collagraph(y)" or "additive print(making)" are clearly the best here, especially the former, and I think it would be very useful to have them in the glossary, so I'm making an entry with them and without my own suggestion (which is here in case it's of any use). I wouldn't use "additive engraving" personally.
Cheers!