During the weekends of 1925-1927 he would study under Yitzhak Frenkel (a painter of the Ecole de Paris) at his studio in Tel Aviv, where he encountered the influence of modern French art.

In 1947, Castel helped to found the "New Horizons" (Ofakim Hadashim) group together with Yosef Zaritsky, Yehezkel Streichman, Marcel Janco and others.

[4] In the 1930s and 1940s, many of Castel's paintings depicted the lives of Sephardic Jews in the Holy Land, revealing the influence of Persian miniatures.

[7] The technique utilized ground basalt rock mixed with sand and glue, infused with the rich colors that became his trademark.

[5] The works were embellished with archaic forms derived from ancient script, symbolism and mythological signs from Hebrew and Sumerian culture.

[9][10][11] His museum in summer of 2024 showcased an exhibition of 74 artists including Naftali Bezem, Yosef Ostrovsky and Yitzhak Alexander Frenkel (Frenel).