Mr Hoar's younger brother, Peter Hoar, who is also involved with the family business that has been running since 1901, said waterblasting headstones was rewarding.
"It gives me some pleasure seeing them before and after, it makes a huge difference and doesn't need to cost endless money."
Roddy McKenzie, from the cemetery restoration group, said the group was committed to cleaning up the Masterton cemetery and were first going to focus on the Pioneer Cemetery.
"The older we get, the more history we lose."
He said eventually the group planned to have each pioneer's individual story next to their headstone, so people could learn more about Masterton's history.