By 1641 the young Andrea was living with Nicolò Amati and being instructed in the art of violin making, probably working alongside Francesco Ruggieri and Antonio Stradivari who were also apprentices at the same time.
Anna Maria soon bore a daughter, Angela Teresa, followed just over a year later by a son, Pietro Giovanni, who was eventually to carry on his father's violin making.
Eventually entire instruments appear to be made by Pietro Giovanni's hand, though they contain the original Andrea Guarneri label.
Andrea himself clearly sought to distinguish between the work of him and his family from that of other workers in his workshop by inserting labels saying Sotto la disciplina (Under the discipline of...).
Instruments coming out of the Guarneri workshop also continue to show the inspiration of Andrea's eldest son, though he was living in Mantua.
In his will Andrea Guarneri recorded for posterity the bitterness he felt toward his elder son Pietro for having left the family and moving to Mantua, and for his ingratitude to them even before that.
The earliest Andrea Guarneri violins unsurprisingly closely resembled the Amati style with rounded 'bouts and slender corners whose looser curves end with a slight flat.
[5] Later in his life the corners become shorter and blunter, edges heavier, and arching more pinched which became somewhat irregularly formed at times with exaggerated fluting.
The Scrolls when made by Andrea Guarneri were generally neat, but when assisted by Giuseppe Filius, one may notice that they were more youthful not necessarily more finely finished.
[2] Andrea Guarneri also pioneered a smaller sized violoncello, which evolved over the course of his lifetime from the Amati form and style, though credit may also be due to his acquaintance and competitor, Francesco Ruggieri who made many 'celli in the same period.