Doesn't it depend on how many components need to be painted on the assembly line?
Making up numbers - if they put together 25 units a day, and need to spend an extra 5 minutes per unit coating, that adds an extra two hours a day. 2 hours seems like a lot. Reducing the number of units made, adding a skill/staff, adding the cost of the coating, stuff & space used to apply the coating, would all have to be made up for somehow.
If this was a bigger industry, there might be huge assembly lines making at least thousands of these a day, and the extra cost becomes easier to absorb.