I used that blue die once... only once... never again!Liquid Harvest Lazer Blue Concentrated Spray Pattern Indicator - 1 Gallon (128 Ounces) - Perfect Weed Spray Dye, Herbicide Dye, Fertilizer Marking Dye, Turf Mark and Blue Herbicide Marker https://www.amazon.com/dp/B0049I9OBA/ref=cm_sw_r_cp_apa_i_tSKeEbRM0626F
Note: Use chemical gloves or you will have blue hands for a while.
For those wanting to try soap, or water, or whatever... I say go for it. The hard part of this process is making the cuts. If your mix doesn't work all you have to do is take a walk in the spring with a sprayer and hit anything that's sprouting. I like using diesel but have used straight gly with a paintbrush on cuts with success. I think the most important thing is getting the chemical on the cambium layer quickly (before it dries over).