Effectiveness of Using Bluestone and Washing Soda for Potato Blight

I want to spray my potatoes for blight using the bluestone and washing soda remedy. How effective is this in comparison to newer remedies such as Ditane? Can you also provide the recommended proportions of bluestone and washing soda to be used? Thank you.

The old sprays, like Burgundy mixture which uses copper sulphate (bluestone) and washing soda, or Bordeaux mixture (bluestone and lime) are still effective for potato blight control. The heavy metal copper is the active ingredient. Bluestone can be hard to obtain, and the solution must be freshly made. It needs to be repeated frequently. A mixture of 100 grams each of bluestone and washing soda is dissolved in 5 litres of water, and the two are slowly mixed and used immediately. On the other hand, Ditane contains mancozeb, an effective fungicide that lasts better on the leaves than Burgundy mixture.