Factories across the country were temporarily laid low in the measure meant to put pressure on employers after an unsuccessful round of labor negotiations ended this week in Dortmund.
Automaker Audi was hardest hit with about 5,000 workers from its factories in Ingolstadt and Neckarsulm taking to the picket line.
The employers federation rejected the demand for an eight percent raise, arguing that companies would have to shed jobs if wages rise too much due to the economic crisis and weakening economy. Instead, employers have offered a 2.9 percent pay increase.
"We are not responsible for the crisis on the financial markets and we're also not ready to take the blame for the gamblers and financial jugglers," said IG Metall chief negotiator Harmut Meine.
If no pay deal is reached, "the real wave of strikes" would start Monday, union chief Berthold Huber told Friday's Bild newspaper.