Numsa spokesperson Dumisa Ntuli said the second round of bargaining came after the employer rejected the union's demands.
Ntuli said the union had requested the employer federation to respond concretely on Wednesday.
He said the negotiations were part of collective bargaining arrangements that determine wages and working conditions of 310 000 workers employed in the engineering and steel industry.
"Numsa is disappointed that the employer federation failed to respond last week to the workers' demands. We hope and trust that Seifsa will practically and logically respond to the union demands, taking into account the grim economic conditions that are facing workers," said Ntuli.
He urged the employer federation not to apply its power tactics to persuade the union to accept lower increases.
"Numsa wants wage increases that will broaden the base of the workers who can participate meaningfully in the economy," he said.
The union would not accept lower wages and variations of the existing conditions of work.
"Our fight to win better wages and working conditions remain strong and unaltered in the industry."
The union demanded that the wages be increased by the consumer price index (CPIX) rate plus a five percent improvement factor.