A strike by Starbucks workers over the company's updated dress rules gained momentum on Thursday.

Starbucks Workers United, a union for the company's U.S. employees, reports that over 2,000 baristas in 120 American stores have been striking since Sunday, disagreeing with the updated dress code.

From Monday, Starbucks is introducing new rules about what staff can wear under their green aprons. Employees in the US and Canada working in Starbucks-owned and licensed stores will need to wear a plain black top and trousers or jeans in khaki, black, or dark blue.

Previously, baristas were allowed more freedom in choosing dark colors and patterns for their shirts. Starbucks believes the updated rules will highlight their green aprons and create a consistent look for customers, helping to foster a friendlier atmosphere in their stores.

However, Starbucks Workers United, the union for employees at 570 out of Starbucks' 10,000 American stores, believes the dress code should be discussed as part of their negotiations.

Paige Summers, a Starbucks supervisor in Hanover, Maryland, believes Starbucks has lost sight of its priorities. She argues that instead of valuing the opinions of baristas who create the Starbucks experience, the company is focusing on less important issues, such as a strict new dress code. Summers added that customers are unlikely to be concerned about staff clothing when faced with long waiting times for their orders.

Summers and others also criticised the company for selling Starbucks-branded clothing online that employees were no longer permitted to wear at work. Starbucks stated they would provide each employee with two free black T-shirts when the new dress code was announced.

On Wednesday, the Starbucks Workers Union announced that 1,000 employees had participated in walkouts across 75 stores in the US. Starbucks responded that the strikes had a minimal effect on their 10,000 company-run stores in the US, adding that some stores were only closed for short periods.

"Starbucks stated that it would be better if the union focused on returning to negotiations instead of protesting by wearing black shirts. They added that over 99% of their stores are currently open and serving customers, as they have been throughout the week."

Readers of the Associated Press expressed different opinions on the Starbucks dress code, with some feeling baristas had little reason to complain, as many shops have similar rules. Others argued Starbucks should prioritise better drinks and happier workers, instead of focusing on employee clothing.

Maddie Mucklow, a Starbucks manager in Seattle, has expressed her support for the new regulations.

Mucklow admitted that the new dress code presented a challenge for staff initially. However, she believes it now provides a clearer framework for professional appearance, allowing for individual expression within agreed limits.

Since 2021, Starbucks employees, organised as Starbucks Workers United, have been creating unions in stores across the U.S. Despite agreeing to restart negotiations in February 2024, Starbucks and the union haven't yet reached a final contract agreement.

This week, the union stated they have officially complained to the National Labor Relations Board, claiming Starbucks is not negotiating the new dress code.