It is a processing phase that consists in cutting the gut with a horn-shaped tool, with a central blade: two strips are obtained, one of which is more rough inside, and one smooth and regular outside.
With the external strip the cantini and thinner strings are made, with the internal one the largest.
It is a typical technique of German string makers, but abusively practiced also in Italy, where it was prohibited: Cordedrago used it in the past only to make the Minikins, more resistant than the Cantini di Napoli, but with a less beautiful sound.
Currently, I also need to cut the gut for research: basing on a study by Andreas Schlegel on a manuscript sheet inserted in a music volume of Denis Gaultier, I am trying to reconstruct a hypothetical baroque lute string set based on the number of strips indicated in the text.
However Cordedrago was the first one to use only whole lamb guts, that is, not cut into one or more strips, simply because they are already in themselves very fine and regular, substantially devoid of taper and roughness.
Instead all the other modern string-makers use mutton or ox gut (the use of which is not attested in the string tradition), and consequently they are forced to cut it both to obtain individual thinner threads, and to eliminate the irregular parts, and to remedy the problem of the conicity of the guts of adult animals, which if twisted whole would give rise to thicker strings on one side than the other and therefore false.
It is no coincidence that the ancient Statutes of the Roman string makers (see: Patrizio Barbieri, Roman and Neapolitan Gut Strings) prescribed not only pecuniary penalties, but even flogging, for those who "split" the guts: the use of whole guts guarantees greater resistance to surface wear due to the action of the fingers or the bow, while the fineness and regularity of the threads allows twisting strings so uniform that they could be played even without rectification.