7 C.F.R. § 91.6

(a) Services may be furnished whenever a Science and Technology staff is available and the facilities and conditions are satisfactory for the conduct of such service.

(b) Laboratories may provide limited service on Saturdays and Sundays at a premium fee. Weekend service may be obtained by contacting the laboratory director or supervisor.

(c) Holiday and overtime laboratory service may be obtained with a minimum 24 hour advance notice, at a premium fee, by any prospective applicant through the laboratory director or supervisor.