Mannerist painters expressed emotion in their paintings by:

Renewing and developing all the skills and techniques acquired during the Renaissance

Explanation:

    Some historians consider it a transition between the Renaissance and the Baroque, while others prefer to see it as a style per se. What is certain, however, is that mannerism is a consequence of a classic revival that is decaying. Artists are forced to look for elements that will allow them to renew and develop all the skills and techniques acquired during the Renaissance.

    Mannerism was a protest against what was felt to be sterile rationalism and the conservative property of classicism. Mannerist rebels doubled, split, and nearly broke the rule-driven mindset. His designs were eccentric, complex, full of surprises and contradictions. For the classicists, the regular rhythm was God. To a mannerist, divine was the unconventional. Indeed, all artists of this period who deliberately sought to create something new and unexpected, even at the expense of the "natural" beauty established by the great masters, may have been the first "modern" artists. We will see, in fact, that what is today called “modern” art may have had its roots in a similar impulse to avoid the obvious and achieve effects that differ from conventional natural beauty.