For the first time in Eastern Europe the Tempera method became wide-spread in the murals of the Tarnovo School of Art. That technique allowed the work to proceed slower than the fresco method as well brighter and more saturated colouring and had potential for more additional colours. The fresco technique continued to be used, for instance in the beautiful frescoes of the Rock-hewn Churches of Ivanovo and the chapel of the Hrelyo Tower in the Rila Monastery.
During the Second Empire the murals on the church walls closely encompassed every part of the surface: walls, vaults, columns, wall piers, arches, apses. Their positioning was in horizontal layers according to the church canon.
On the first layer were depicted saints who were usually stepped on a high painted plinth, which is one of the characteristic features of the School. Its lines imitated the panel plates of coloured marble. The selection of saints depended on the preferences of the ktitors or on the general theme of the frescoes. Typical feature of the Tarnovo Artistic School are the numerous depictions of warrior-saints. For instance, in the Boyana Church there are ten warrior-saints. Widely spread was the image St Demetrius of Salonica, the patron saint of the Asen dynasty, who was particularly popular in Bulgaria in 13th and 14th centuries. The ktitors were depicted in the narthex of the churches. Portraits of many noble Bulgarians from the Middle Ages have survived throughout the centuries due to that practice. In the Boyana Church are preserved the images of Emperor Constantine Tikh Asen, his wife Irina, sevastokrator Kaloyan and his wife Desislava. Тhere is a beautiful fresco of Emperor Ivan Alexander in the ossuary of the Bachkovo Monastery and in the church of Dolna Kamenitsa there are eleven images: despot Michael (son of Michael Shishman) his wife an unknown noble holding a model of the church; his wife and children and two clerics. Images of warrior saints and ktitors were common in the preserved detailed mural paintings on the foundations of the churches in Trapezitsa. These paintings are featured with mild tones and a sense of realism in the rendered portraits and cloths. One of the churches in Trapeztisa was covered with mosaics. Тhe palace church also had some mosaic decoration. The unique and realistic portraits in the Boyana Church are considered to be forerunners of the Renaissance. The wall piers and the arches were often decorated with medallion-shaped bust images of saints. Magnificent examples of those can be observed in SS Peter and Paul Church in Tarnovo. Along with the traditional scenes such as "Christ's passions" and "Feast cycle" in the second layer; "Christ Pantokrator" in the dome and the Madonna with the infant Christ in the apse, there were also specific images and scenes. In the narthex of the SS. Forty Martyrs Church in Tarnovo there were frescoes of St Anna nursing the infant Mary and St Elisabeth nursing the infant John the Baptist, unfortunately the last one did not survive. The iconographic type Galaktotrophousa was a predecessor of the widely-spread images of Madonna with the infant Christ in Western Europe. Although it was canonical, that scene was rarely used in the Byzantine Iconography. In the 35 calendar scenes from the same church some of the characters were painted with contemporary garments. The large number of images of Jesus Christ in the Boyana Church makes an impression: Pantokrator (All-powerful); Emmanuel (Young man); Evergetes (Blessing); Mandilion; Keramidion and the unique image Christ Ancient of Days in which He is depicted as a white-bearded Old man.
Thеre are original themes in the Transfiguration of God Chapel in the Hrelyo Tower situated in the Rila Monastery. In the dome is depicted the composition Sophia-Great Wisdom of God and in the narthex Psalms of David. The scenes Musicians and Horo are especially interesting because they represent the cloths and the way of living of the Bulgarians during the 14th century. There are scenes of Saint Ivan of Rila life. Although there are relatively few preserved monuments of the Tarnovo School of Painting, they refute the popular opinion that the religious murals are inveterate and that they are inappropriate for artistic imagination.
The archaeological research shows that some public edifices and the palaces were also richly decorated with mural paintings but unfortunately the few remaining fragments are not enough for the themes to be determined. The fragments of richly dressed men were discovered in the throne hall which suggests that probably the hall was decorated with the depictions of the Bulgarian Emperors and Empresses.