About a week ago I bought a multi-pack of Mint flavour sugar free chewing gum and chewed just over one packet worth. I then packed it into the slit in my handle, and inserted the blade. My assumptions about gum have been, and are still being tested. Encountering chewing gum in unexpected places, it is usually hard and stuck convincingly to something else. I assumed this was because it had dried out. Consequently I had it in my mind that once the gum dried in my knife handle the rigidity it delivered would hold the blade in place.
One week later and the gum is still soft. I have tried a number of strategies to dry it out which include leaving it outside in the damp cold, but this didn’t work. I then left it on a radiator hoping the heat would dry it out, but the gum just became more pliable. Innovatively, I left it in the freezer for 24 hours and this did harden it up, but throughout the following day the gum became maliable again. I then left it buried in wood ash in my wood burner for three days. Because the ash is dry I thought it would draw out the moisture from the gum, but no, it is still maliable.
I am slowly working out that I am attempting to manage two variables: temperature and moisture content. My assumption that chewing gum hardens is I think correct based upon all the bits I have found stuck to things in the past. However, I read a comment on a blog post today that stated that chewing gum would be hard at room temperature but softens as it reaches body temperature through the chewing process. If correct then it is temperature that is the key factor, but not necessarily for reducing moisture content. Perhaps moisture content is not a factor here? I have also been reading about Neanderthal birch bark tar production where the tar is ‘sweated’ out of the bark, so again heat seems to be the key factor. If correct then perhaps my chewing gum hafting is as hard as it will get at room temperature, probably a similar hardness to when I initially started chewing it. Like the famous parable that people in far northern latitudes have fifty words for snow, I think I could do here with a few more descriptors than ‘hard’ and ‘soft’.
It gets even more complicated if I introduce data into the discussion. Whilst the knife has been languishing in the ash of my wood burner I have tested it daily for moisture content with a ‘Moisture Meter’. I usually use it on wood to see if is dry enough to burn, but I have been using it on the gum and the wooden handle once a day. It indicates that the gum has more moisture than the wooden handle, and both the readings for the gum and handle are remaining pretty constant. This suggests that the gum does in fact contain moisture, and contradicts my emerging ‘plastic’ hypothesis.
Finally, there is the issue of the chewing gum found stuck to things in the outside world, and that has become hard! How does that happen? What I need is the input of a materials scientist, and funnily enough my niece Isabella is a materials scientist. She thinks that the gum outside may be oxidising and it is the oxidisation process that makes the gum become hard. So time becomes another factor in the discussion, and probably surface area as well. TBC.