Sevillian Spanish /s + ptk/ clusters are often produced with gemination of the consonant following /s/ and postaspiration (/pasta/:[pahta]-->[pat:ha]) (Ruch and Peters, 2016). Spanish voiceless stops are unaspirated, but some argue that postaspirated stops are phonologizing in Seville (O'Neill, 2010; Gylfadottir, 2015). Acoustically, postaspiration is long VOT. Articulatorily, it is described as a laryngeal gesture moving across the stop, continuing past the release (Torreira, 2007). Previous work focuses only on /s + ptk/. This acoustic study examines /sC/-clusters with voiceless stops, voiced stops, and sonorants, extending our understanding of the mechanisms behind postaspiration. Seven Sevillians read paragraphs containing /sC/ and /C/ words (/kaspa/-/kapa/). All clusters show gemination. Compared to /ptk/, /s + ptk/ clusters have long postaspiration, resist intervocalic voicing, and result in higher pitch on the following vowel (a cue to contrastive aspiration in many languages, Dmitrieva et al., 2015). /s + bdg/ clusters have stronger constriction, higher COG, and less voicing than intervocalic (spirantized) /bdg/. /s + mnl/ clusters differ from /mnl/ only in gemination. Gestural overlap thus occurs in voiced and voiceless clusters, and appears to result from higher-level realignment as opposed to unintentional mistiming (Parrell, 2012). Postaspirated voiceless stops are unlikely to phonologize because the process occurs with both /s + bdg/ and /s + ptk/, giving different results.