Section 5. If a controversy exists between an employer and his employees, the board shall, upon application as provided in the following section, as soon as practicable visit the place where the controversy exists and make careful inquiry into its cause, and may, with the consent of the governor, conduct such inquiry outside the commonwealth. The board shall hear all persons interested who come before it, advise the respective parties what ought to be done or submitted to by either or both to adjust said controversy, and make a written decision thereof which shall at once be made public, shall be open to public inspection and shall be recorded by the board. A short statement thereof may, in the discretion of the board, be published in the annual report, and the board shall cause a copy thereof to be filed with the clerk of the city or town in which said business is carried on. Said decision shall for six months be binding upon the parties who join in said application, unless by agreement of both parties it is stipulated in the application that the contract is to run for a longer period of time, in which event the decision of the board will be binding for the length of time agreed upon by both parties in their application.