Faculty at St. Clair, Lambton and 22 other Ontario colleges have gone on strike as part of a walkout that will affect more than half a million students.

The Ontario Public Services Employees Union said the two sides could not resolve their differences ahead of the midnight deadline.

There's no indication yet when talks might resume.

There will be no classes at St. Clair College until the dispute is settled and 321 staff members in Windsor and Chatham are back at work, according to spokesperson John Fairley.

"All teaching is suspended, so it's not like there are going to be part-time people coming in, teaching classes or doing exams," he explained. "If you're a student, you can still come to the college, and there's computer labs. Our varsity areas in both Chatham and Windsor, Healthplex and Sportsplex are open."

Bernie Nawrocki, head of OPSEU Local 138 at St. Clair College, said the union was seeking greater academic freedom for faculty members and better conditions for part-time staff. The ratio of part-time to full-time faculty is about 70/30 and the union would like it to be 50/50, said Nawrocki.

The College Employer Council called the strike completely unnecessary. It said  the union's demands would have added $250 million in annual costs.

Fairley added that during the strike the school's library and food services will remain open.

Community events at the Centre of the Arts downtown will also be unaffected, but picket lines could cause traffic issues around college entrances.