Texts on wood and bark

For obvious reasons we are accustomed to thinking of biblical texts on papyrus and parchment (the most obvious reason is that most biblical texts were in fact written on papyrus and parchment). Among the minuscules we also find manuscripts written on paper. We may also be vaguely aware of biblical texts written or inscribed on other material (ostraka, inscriptions etc.), which are of significant interest on the liminal margins of the book culture of early Christianity (for a survey of this material [which never once uses the word "liminal"] try this). Among OT manuscripts we also have material on lead and silver.

Two other types of material are of interest. One is the wax tablet. These are reasonably common, and were used for teaching, composition, and even semi-permanent records.

It is interesting that there are at least thirteen Greek OT texts surviving on tablets (acc. Fraenkel's Verzeichnis), including for example this one in Michigan, with Proverbs 7.3-13 in Greek - where, as appears to be generally the case, text survives because it penetrates through the wax into the wood (and the wax does not survive):

As far as I am aware (feel free to correct me), there are very few examples of tablets with text from the NT, and none in the Liste (although there is an interesting set of discussions about the compositional possibilities of wax tablets and the gospels here and here and here). For possible examples, both containing portions of the Lord's Prayer see P. Baden 4.60 (van Haelst 346); van Haelst 349 (unedited).

Another option is wood and bark strips. Perhaps the most interesting are the well known Vindolanda tablets - preserved in northern England where there was a peculiar parallel with conditions for papyri in Egypt - the papyri were preserved in Egypt because they never got wet, the Vindolanda tablets were preserved in England because they never got dry. (this one is about the fighting capabilities of the wretched Britons):

There are no biblical texts from Vindolanda, but it may well be the case that wooden surfaces were used more widely in Europe. Recently 915 texts on wood and bark were excavated from Novgorod, and among the many more there may well be Christian texts among them.