Alright, just two comments:

1. When the pH4 dilute phosphoric acid was added to the bark, it began to bubble a little. Like some kind of reaction was already starting. Also, after the cooks the liquid was a thick brown, definitely NOT red like acetic or HCl tends to produce.

Two four litre cooks were done (1Kg of bark used) and combined and reduced. After reduction there is about 2L - was it taken too far? It should be ok...

2. When it came to add NaOH, to the solution still hot from reduction, about two teaspoons was initially added. Surprisingly the solution turned milky white almost instantly. On closer inspection it was actually a precipitate.

Note that this is suspected to be high content bark, so perhaps this would make sense

At the moment the vessel is too hot to add more NaOH (scary stuff) so it'll be left to cool for the moment. More will be added later. Perhaps some Shellite will be added first so the precipitate has somewhere to sit before proceeding to add more NaOH