The 24-year-old hit 11 fours as he shared a 73-run fourth-wicket partnership with Hamish Marshall (51).
Marshall departed after being caught well by Jesse Ryder attempting to drive Jamie Porter, whose four wickets restricted the away side to just 262.
In reply, Liam Nowell trapped Nick Browne for one but England captain Alistair Cook helped Essex reach 39-1.
Gareth Roderick hit an unbeaten 88 as Gloucestershire and Essex shared an even first day at the County Ground.