Reasonable Cost of
Soap/Wax per minute?
$0.04 per minute
If sales are $0.44 per minute, $0.04 is ten percent of sales.
Ten percent is reasonable for cost of goods chemicals.
$0.44 per minute for 4-minutes is $1.75.
So, better question is $0.44 per minute sales reasonable?
As one person mentioned, chemical at self-serve is chump change.
For example, what is going to put more money in your pocket, increasing sales by 10 percent per minute ($0.04) minute or reducing cost of chemical by ten percent per minute?