張愛玲的信大半寫在洋蔥紙（onion paper）上，隔了多少年，潔白如舊，折縫的地方也不會破裂。有些信則寫在以紙漿（pulp）為主要成份的劣紙上，色澤早已轉黃，折縫處黃色更深，且容 易破裂。有大志的讀者，最好從小養成用洋蔥紙或其他高級紙張寫信的習慣。說不定自己真會成了大名，連早年寫的信件也有可能流傳後世的。---夏志清先生
Onionskin or onion skin is a thin, light-weight, strong, often translucent paper. It was usually used with carbon paper for typing duplicates in a typewriter, for permanent records where low bulk was important, or for airmail correspondence. It typically has a 9 pound basis weight, and may be white or canary colored.
In the typewriter era, onion skin often had a deeply-textured cockle finish which allowed for easier erasure of typing mistakes, but other glazed and unglazed finishes were also available then and may be more common today.
Onionskin paper is relatively durable and lightweight due to its high content of cotton fibers. Because of these attributes and its crispness when folding, onionskin paper is one of the best papers to use for advanced paper airplanes. Paper airplanes made from onionskin paper tend to fly very well due to its low weight and high integrity once folded.