query: SELECT ?material ?painting ?materialLabel ?paintingLabel
  WHERE
  {
    ?painting wdt:P31/wdt:P279* wd:Q3305213;
              p:P186 [ ps:P186 ?material; pq:P518 wd:Q861259 ].
    ?material wdt:P31 wd:Q16521.
    SERVICE wikibase:label { bd:serviceParam wikibase:language "en". }
  }