Today was an interesting practical exploration day. Someone invited me to their back yard and showed me what is actually the “inner bark” of the apple tree. We explored removing it from the trimmed apple tree branches, and now I have some experience. For instance, I know that there is no point trying to remove it (or even the whole bark) from the branches that have been cut a while ago, it is much easier to strip the bark (and separate the inner bark if needed) from the freshly cut branches.
The apple tree dyestuff I have purchased is always whole branches, and they still work, but for some reason all of the late 19th century Ukrainian pysanky-related sources insist that the bark should be stripped from the branches and only the bark should be used for the dye. Korduba even uses a Ukrainian word which I do not know and have not found in the dictionaries, and I am guessing he could be referring to the inner bark:
To obtain the yellow dye, from the wild apple tree peal the bark with sumat’ [inner bark?], soak for some time in room temperature and then hot water and the dye is ready. … Because of that yellow dye is everywhere called as “apple dye”. Besides that, in all villages it is told that earlier and in some places even today the yellow dye is obtained from onion skins by boiling them with water. But that dye looks more reddish and never looks as nice as apple dye. (Korduba 175, my translation)
There are also old Estonian recipes using apple tree bark (and maybe also specifically the inner bark) to make the dyes for fibres, and Estonians had some very interesting ways of processing the barks to achieve strikingly different results, so I have heard (and also have seen some amazing photos or current experiments).
We also went and checked out one of the three claimed “wild apple” trees in Tartu, because it was nearby, and have found out in quite an interesting turn of accidental communications, that the specific tree was entered into the database by mistake, it is not wild. So the “wild” aspect of the apple tree bark used for dye is still inaccessible to us. Let’s see how that aspect unfolds.