Selvan Manoharan was startled as the man armed with a gun stormed into his store in Essex, near London, and threw a bag on the counter demanding it be filled with cash.
As the robber momentarily turned away to check behind him, Manoharan took his chance and grabbed two cans of the scarlet spray.
The 41-year-old father of two forced the robber to flee empty-handed after he covered his face in red dye, which will last at least for a week.
"He didn't want to talk, he was covered up and his voice was muffled. I tried to make him speak to see if I recognised him. I could see he was scared, I decided he was a chicken so I got him," Manoharan told 'Metro'.
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He said while his wife was upset at him for taking the risk, he was proud that he had been able to protect his shop and 300 pounds of earnings in the till.
Police in Essex have since arrested two teenagers, aged 17 and 16, in relation to the incident.