Pour the kvass through a strainer or cheesecloth, leaving a 0.5 l starter culture. Fill with fresh water, put 3 tbsp sugar and 15 raisins, stir and put again for 3 days.
And so until then, until not have had enough. For the color you want to add black crust brown bread.
If you just drink kvass, you can sweeten it. For mayo need mix all products in blender.