Folster was the Labor candidate for the seat of Orange at the 1927 state election, but lost to sitting Nationalist MLA John Fitzpatrick.
The rural Orange area was suffering badly due to the Great Depression, and Folster campaigned on Labor leader Jack Lang's radical proposals for a resolution.
It was well received by both Labor traditionalists and the district's increasingly desperate farmers, and Folster narrowly won the traditionally conservative seat.
His career was to be short-lived, however; an increasingly controversial Lang was dismissed by the state Governor in 1932, and Folster was defeated by United Australia Party candidate Alwyn Tonking at the resulting election, one of many Labor MLAs to lose their seats that year.
Later in life Folster was a boiler inspector for the Western districts, and worked for the government during World War II.