Section 20. All cans, moulds or other containers used in the sale of ice cream or other frozen desserts and/or frozen dessert mix by measure shall be of the capacity of Massachusetts standard liquid measure. Such cans, moulds or other containers shall be sealed, as hereinafter provided, by the manufacturer thereof, or by a sealer, and shall not be legal measures except for ice cream or other frozen desserts and/or frozen dessert mix. When sealed by the manufacturer, such containers shall be marked with his name, initials or trade mark. They may also be marked with any other designating mark assigned to him by the deputy director; provided, that he has agreed to conform to the regulations made by the deputy director relative thereto. When such containers have not been sealed by the manufacturer, they shall be sealed, before they are used, by a sealer, and the dealer who intends to use them shall bring such containers to the office of such sealer for that purpose, but no fee shall be charged for sealing them. The sealing of such containers by the manufacturer shall not be held to exempt the user from the laws relating to the giving of false or insufficient measure, or the using of a false measure, or having in his possession a false measure with intent to use.