1908-1914 Period

http://www.oxfordmusiconline.com/subscriber/article/grove/music/40686pg3#S40686.3,

This link is about Bartok's creativity's 1908-1914 period which Bluebeard's Castle was written also. Piano pieces were intensely written in this period. It is said that French effects had an important role. While the characters were reflected,for Bluebeard "smooth and pentatonic lines" and for Judith "more chromatic and angular writing" were used. Here is the part which is directly about the opera:

"In the first half of 1910 Bartók’s recognition as a composer appeared to be growing, and with it requests for him to perform. At a ‘Hungarian festival’ concert in Paris on 12 March 1910 he played several of his own works, as well as pieces by Szendy and Kodály. A press comment about these ‘young barbarians’ from Hungary probably prompted Bartók to write one of his most popular piano pieces, the Allegro barbaro bb63, in the following year. In other works of 1910–12 French influences are at their most apparent, with Debussy’s mark perhaps being too readily identified, notably in the orchestral Két kép (‘Two Pictures’) op.10 and the Four Orchestral Pieces op.12. The intervening op.11, the one-act opera A Kékszakállú herceg vára (‘Bluebeard’s Castle’) (1911) is, however, a masterful Hungarian emulation of the realism of Debussy’s Pelléas et Mélisande. Written to an expressionistic libretto by Béla Balázs about the ‘mystery of the soul’, the action of Bluebeard’s Castle is negligible, involving just two singing protagonists, Bluebeard and his new wife Judith, who progress through the opening of the eponymous castle’s seven doors, drawn by the woman’s curiosity. The opera’s climactic turning-point comes at the fifth door, to Bluebeard’s kingdom, after which Judith’s jealousy becomes obsessive, leading to her eventual entombment, along with all Bluebeard’s previous wives, and eternal darkness. Bartók’s work changed the course of Hungarian opera by successfully developing a fluid form of Hungarian declamation of Balázs’s ballad-like text, based largely upon the inflections of parlando rubato folksong. He also managed to characterize the protagonists modally: Bluebeard through smooth, pentatonic lines; Judith through more chromatic and angular writing. Bartók’s operatic conception owed much to Wagner, particularly in his use of a recurring minor-2nd ‘blood’ motif, while the orchestration is still indebted to Strauss, whose influence in other compositional respects had waned. The adjudicators of two Budapest opera competitions of 1911–12 nonetheless found little merit in this ‘unperformable’ work, and it was assigned to Bartók’s drawer."