It had been printed on first-class paper by the best printer in Calcutta
Svarupa Damodara presented Srila Prabhupada a xerox copy of the very first Back to Godhead, published in 1944. It was discovered in the Library of Congress. A group of four or five devotees went there to search out a copy of the Surya-siddhanta and other astronomical literature. Although they didn't find that book, most of Prabhupada's books were there. Pradyumna was looking through the index and discovered the BTG.
Prabhupada was surprised to see it, and said that it may have been sent to the Library by his Calcutta distributor, the biggest in Bengal. He told us it had been printed on first-class paper by the best printer in Calcutta, Sarasvati Press. It was released on the Vyasa-puja day of Srila Bhaktisiddhanta Sarasvati.
Reference:Transcendental Diary Volume 3 by Hari Sauri Dasa