Section 3218 - Evidence of age1. Evidence showing that the minor is of the required age shall be presented as follows: a. A duly certified transcript of a birth certificate filed according to law, or duly certified transcript of a record of baptism, giving the date of birth; or, if not available, b. A passport showing the date of birth of the minor; or, if not available, c. Other documentary evidence or other recorded evidence in existence two years or more, and satisfactory to the certificating officer, except an affidavit of age. 2. Certificate of age. A person over eighteen years of age may apply for a certificate of age to the superintendent of schools, the district superintendent, or to the certificating officer. Upon such application a certificate of age, containing the name, date of birth, address and signature of the applicant, shall be issued to him if he furnishes such evidence that he is over eighteen years of age as is required for the issuance of an employment certificate. Such a certificate of age or an employment certificate previously issued for such person shall be conclusive evidence for an employer that the person has reached the age certified to therein.