United Steelworkers picketed outside of 3M’s Cottage Grove chemicals plant this week after members rejected the company’s latest labor proposal.

Members of local 11-00418 voted down 3M’s latest contract proposal on Monday, saying they were unhappy that 3M proposed lowering weekend pay and 401(k) contributions. 3M also wants to increase its ability to mandate extra work shifts. Union members also balked at changes in the overtime structure.

“We aren’t going to accept some of the concessions that they’re looking for,” said union local president Mike Schanks. “We’re willing to bargain, but some of the things they want are just too much to ask.”

3M spokeswoman Fanna Haile-Selassie declined to discuss 3M’s specific proposal. But she said: “We still are working with the [union] in good faith. Our goal is to find ways we can continue to operate successfully while still providing competitive pay and benefits.”

Members picketed outside the plant Wednesday and said they may again set up pickets outside of 3M’s headquarters in Maplewood, like they did last month.

About 400 of the plant’s 763 employees are covered by the union contract. The three-year labor contract expired in August and has been extended temporarily while the two sides work toward a new agreement. Union and company officials begin talks with a federal mediator Oct. 11.

Last month, the steelworkers gave strike authorization to the union leaders leading their side of the talks. No strike has been called to date. Members have largely picketed 3M before the plant opened, during lunch breaks and during their days off.