The presence of a "invisible mending" has been proposed as an explanation for medieval radiocarbon dating measurements made on the Shroud of Turin. Here we show that the chemical analysis which was to support this theory is not consistent, and no scientific data confirm these speculations. Specifically, the samples of the Shroud image fibers underwent a different cleaning procedure with regards to those allegedly belonging to the medieval mending. There is no reliable indication of the supposedly diagnostic compounds (e.g. gum Arabic, pentoses). The only detectable difference between the samples is the presence of a compound with an aliphatic chain which cannot be identified more in detail, e.g. as sebum. (C) 2016 Elsevier B.V. All rights reserved.