Sallaert produced many devotional paintings for the Brussels court of Archdukes Albert and Isabella as well as for the local churches.
He received irregular commissions from local nobles and produced religious compositions for the Jesuit churches in and around Brussels.
In 1647 he accepted a large commission from the clergy of the Onze-Lieve-Vrouwekerk of Alsemberg to paint a series of 11 compositions on the history of the church.
[3] Sallaert was known in his time as an accomplished draughtsman and it is possible that his paintings and drawings have been attributed to other artists such as Rubens or Jacob Jordaens.
[5] Sallaert's painting style is characterized by its nervous brushstrokes, lively outlines and expressive distortion of the composition and figures.
Through the contrast between bright, untreated surfaces and dense patches of black Sallaert creates dramatic light effects.
A few lines and dark splashes of colour are sufficient in this woodcut for Sallaert to give a strong character to the faces, bodies and garments.
Sallaert's formal language sometimes borders on the caricature and his use of a rare, tinted paper accentuates the experimental character of his woodcuts.
[10] He began to make monotypes in the mid-1640s, normally working from black to white, and produced over twenty surviving ones, over half of which are set at night.
Castiglione created most of his monotypes as black-field images by wiping away ink on a prepared plate thus producing white and grey lines.
[4] Examples of publications on which he worked were the "Perpetua Crux sive Passio Jesu Christi", written by the Jesuit Jodocus Andries.
Some of the tapestry series he worked on were The sufferings of Cupid, The life of Man and the Sapientia or the Powers that rule the World, which had a moralising intent.
[15] In 1646 Sallaert was granted tax relief by the Brussels city government in recognition of his contribution to the tapestry industry.
Sallaert had stressed in his application for tax relief the fact that his introduction of a new style in Brussels tapestry design made it unnecessary for the local workshops to hire non-local artists.
In 1645, only a few months before Sallaert filed his tax relief application, the Brussels tapestry maker Boudewijn van Beveren had hung a cartoon of Jordaens' Proverbs in the church of St Catherine.
Like other contemporary tapestry designers, Sallaert developed a mixture of traditional 16th-century and new 17th-century styles thus blending one-dimensional monumentality and three-dimensional depth.