Following the tour for Facelift, Alice in Chains entered the studio to record demos for its next album, but ended up recording five acoustic songs instead. While in the studio, drummer Sean Kinney had a dream about "making an EP called Sap." The band decided "not to mess with fate," and Sap was recorded and mixed in 1991 with producer Rick Parashar at London Bridge Studio.
Regarding the lyrical content, Cantrell said he wrote "Brother" about his relationship with his younger brother. The song specifically refers to the period after Cantrell's parents divorced, when his younger brother went off to live with his father while he stayed with his mother, and Cantrell said that the song "was a way of trying to build a bridge." Commenting on "Got Me Wrong," Cantrell said he wrote the song about a relationship where one person thinks he or she can change the other person, and added that the song speaks of "the different ways that men and women see each other."
A version of the song "Rooster" was recorded during the sessions for "Sap" and was to be included on the EP, but the band then decided to use the song on their second full-length album instead. This recording is featured on the band's 1999 release "Music Bank".
On February 4, 1992, Alice in Chains released their first EP, Sap. Cantrell said that Alice in Chains released Sap "without any fuss or fanfare so as the real Alice fans could find it." The EP was released while Nirvana's Nevermind was at the top of the Billboard 200 charts, resulting in a rising popularity of Seattle-based bands, and the term grunge music.Sap was soon certified gold.
The album was re-released on March 21, 1995, when "Got Me Wrong" became a hit after its inclusion on the soundtrack to the 1994 film, Clerks. The re-released version included lyrics and slightly different artwork. The aforementioned song, as well as "Brother," were performed live during Alice in Chains' MTV Unplugged concert.
In addition to the CD, the album was also released in a limited edition double vinyl along with Jar of Flies (Jar of Flies was on sides 1 and 2, Sap was on side 3, and an etching of the Alice in Chains logo was on side 4). In the UK, Sap and Jar of Flies were issued as a double CD, as Sap had not previously had a UK release.