I don’t know what it is. The ash had a yellow tinge to it, and when I used it to try and make KOH it left me with this bright yellow solution. Funky colour, shame I don’t know what causes it.

Odd yellow liquid from ashes

It is likely a water soluble oxide of some sort; when I had an accidental fire last year some plastic and an old paint can with paint in it got burnt, and plastic often has metallic compounds in it to give colour and make it more light resistant. Metal compounds used include iron, barium, antimony, lead, nickel, chromium. Some of these aren’t very nice, so this is one substance I definitely won’t be tasting.

The analytical problem is that to carry out a simple flame test the potassium and sodium of the ash would probably mask any other colour present, since they are there in such quantities and give such bright flames.

One thing to try was to neutralise the KOH and CaOH present by the addition of vinegar, and see what that did to the colour. I took a sample and added acetic acid, it foamed and bubbled nicely, and the solution cleared slightly, but is still bright yellow. Now to work out how to separate the substances that are in solution.