Jim Smith checks the consistency of his maple syrup as steam rises from a large evaporator at the Smith Brothers Maple Syrup business on Rowe Road in Skowhegan last week. Smith and his brother Patrick are collecting enough maple sap to make 600 gallons of syrup, plus candy and cream. Part of the operation includes 5 miles of lines to collect the sap, though some is still hauled by hand. He said freezing nights and warm days are needed to make the sap run from the trees. “There is a small window to collect sap and you have to be ready,” Smith said. Maine Maple Sunday — Maine’s statewide maple syrup celebration — is this Sunday.