After a brief stint in the British army, from which he was discharged on medical grounds, he married his cousin Jill Blyth, a fellow artist at Forbes' school, in 1917.
Garnier had a studio at Trewarveneth, shared with the artist Richard Copeland Weatherby.
[1] His greatest skill was in etching and engraving, in which subjects he gave lessons to such Newlyn school painters as Lamorna Birch.
He studied the work of William Daniell, using his copper plate techniques to produce aquatints.
The artists Park, Smart, Leach and Birch from their colony were provided with studios and permanent exhibition space, and instituted lectures.