Del. Code Ann. tit. 6, § 2-605
(1) The buyer’s failure to state in connection with rejection a particular defect which is ascertainable by reasonable inspection precludes him or her from relying on the unstated defect to justify rejection or to establish breach
5A Del. C. 1953, §§ 2-605; 55 Del. Laws, c. 349; 70 Del. Laws, c. 186, § 1; 74 Del. Laws, c. 332, § 15