Your very welcome.  Happy to help.  I very much enjoy helping others. In  regards to the alcohol properties of witch hazel.  I'm sure they do act as a solvent to remove the urushiol oil.  Then the properties of the herbs are left to  absorb and do their job.  Removing the urushiol oil is the first and most important step.  Second is to absorb some of the healing properties from the herb.  Combination of anti-allergen properties (for ex.  jewelweed is high in selenium) which I believe helps to control the allergic reaction.  I chose each of these herbs after working with many different poison ivy cases.  They basically cover all of the needs for poison ivy  anti-inflamatory/anti-bacterial (in cases someone has caused an infection from scratching) I've seen that happen before.  I try to cover a wide variety of problems in this area.  As you may have noticed, many times the person did not come into contact with poison ivy.  Instead, the may have viral rash/treatable or strep/take caution or scabies and many other illnesses not yet explained.  

I hope this has been helpful and feel free to ask any questions.  I will try to help. All the best for now,  Ruth