A protest by Starbucks workers over the company's new 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 on strike since Sunday, disagreeing with the recently introduced dress code.

From Monday, Starbucks is introducing new rules about what baristas can wear under their green aprons. Employees working in Starbucks-owned and licensed shops in the US and Canada must now wear plain black tops and trousers or jeans in khaki, black, or dark blue.

Previously, baristas had more freedom to wear various dark colors and patterned shirts. Starbucks stated that the updated rules aim to highlight their green aprons and create a consistent image for customers, hoping to foster a friendlier atmosphere in their stores.

However, Starbucks Workers United, the union for employees at 570 out of Starbucks' 10,000 US stores, argued that the dress code should be discussed as part of their collective agreement.

Paige Summers, a Starbucks supervisor in Maryland, believes Starbucks is heading in the wrong direction. She argues that instead of valuing the opinions of baristas who create the atmosphere, the company is concentrating on less important matters, such as a strict new dress code. Summers adds that customers are likely more concerned about long wait times for their orders than the colour of employees' clothing.

Summers and others also criticised the company for selling Starbucks-branded clothing, which employees were no longer allowed to wear at work, on an internal website. Starbucks stated that they would give each employee 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 its 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 varied opinions on the dress code, with some arguing that Starbucks' baristas had little reason to complain, as many stores have clothing rules for staff. Others felt Starbucks should prioritize better drinks and prices, and keeping employees satisfied, rather than employee appearance.

Maddie Mucklow, a Starbucks manager in Seattle, supports 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 personal expression within agreed limits.

Since 2021, Starbucks employees, organised under the name Starbucks Workers United, have been creating unions in stores across the U.S. Despite agreeing to meet again for discussions in February 2024, Starbucks and the union haven't yet reached a final agreement.

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