If it is only to be burned with a blue flame:

The mixture of alcohol (ethanol) and industrial alcohol (methanol) will be better

If you need a beautiful blue color, it is best to add a little cobalt chloride to methanol instead of cotton thread, which contains sodium and will have a strong yellow light.

if purple flame is needed, replace cobalt chloride with potassium chloride.

it's best to buy analytical drugs from stores.

in addition, I don't know exactly how much to add. I haven't tried it. It should be just a little, for example, one liter plus three to five grams (maybe more). You should try it yourself.