Positioning of the upper scripts compared to the lower one(s)
As explained above, the earlier scripts were most often not erased with a pumice stone but washed off gently. As a consequence, the unwanted texts remained faded but visible and created some difficulties for the scribe when copying the new texts, and for future readers as well. Scribes thus sought to avoid graphical collision between the layered scripts that generally made reading difficult. Sometimes they turned the reused parchment sheet to an angle of 90 degrees from the baseline and used one folio of a larger codex folded in half as a bifolio in the new context. This operation helped to avoid the clash between overwritten and underwritten scripts because the new text was copied across the old one. This happens very frequently. For example, in this way the large folios of the pre-Metaphrastic menologion arranged in two columns were recycled in Vat. gr. 984, and the equally large folios of the ninth-century Philo codex in Vat. gr. 316. In both cases, the overwritten and the underwritten texts represent different forms of Greek minuscule scripts. As far as the Latin scripts are concerned, the Gellius, Cicero and Hyginus fragments were treated similarly in Pal. lat. 24.
One folio with two columns of recycled codices folded in half as a bifolio in the new codices (Vat. gr. 984, ff. 169r + 169av; Vat. gr. 316, ff. 99r + 96v)
Scribes also used other strategies to avoid collisions between the graphic presence of one script over another. It often happened that they turned the sheet upside down, as did the scribe of Pal. lat. 24 when recycling fragments of the smaller codices, those of Seneca and Lucian, trimmed to the size of the new codex. Vat. gr. 345 represents an interesting case. The folios of the old majuscule Greek codex with Gregory of Nazianzus’ homilies were so large that each was cut and then folded in half to create a bifolio of the new psalticon, the book of the main cantor of the Byzantine liturgy. Here two bifolios make up one folio of the old codex and four bifolios do a bifolio from the lost codex. As a result of this operation, the orientation of the upper and lower texts varies: it is either identical or the inserted sheets are turned upside down. However, the use of different scripts, the majuscule and the minuscule, already avoided the conflict between the graphical forms of the lower and upper scripts.
One folio with two columns of recycled codex folded as two bifolios in the new codex (Vat. gr. 345, ff. 36v + 37r + 40v + 33r)
Another strategy was to write between the lines of the lower scripts either in the orientation identical with the lower script or on the folio turned upside down. The scribe of Pal. lat. 24, in addition to turning the folios upside down, seems to have paid attention to this when copying texts on recycled folios of a small size.
Sometimes the script of the upper texts completely covers the lower text and the scribe does not take care to differentiate (by providing space) between the overlapping scripts. In such cases, reading is difficult. In such a particular case (Vat. gr. 73), Angelo Mai managed to erase the upper script with great efficacy and rendered the lower text visible in the larger portion of the manuscript, especially in its first half. The ink of the upper text in these sections reacted differently than that of the other sections. These overlapping scripts create major challenges even today in the process of deciphering palimpsests.
Sometimes the manuscript was recycled twice. Such successive steps of recycling produces “double palimpsests” where, beneath the more recent text, we may find two different scripts, each with its own history. The scribal preference of positioning the scripts can be studied in more than one relationship within the context of the oldest script and the second oldest script as well as in the context of the first two and the most recent script (e.g. Vat. gr. 788. pt. B; Vat. gr. 984 + Vat. gr. 1882). It is extremely rare that a manuscript is recycled more than twice and no example of this has yet been found at the Vatican Library.
Double palimpsest (Vat. gr. 788, pt. B, ff. 4v + 5r: the oldest lower text was copied in Liturgical Majuscule, the more recent lower text in minuscule)