65-70% alcohol is far too strong you risk irritating and drying the skin on your hands, reduce it to 25% and 75% distilled water.

Eucalyptus and tea-tree oil are antiseptic, antiviral and a bactericide*. I would include cinnamon bark and clove essential oils as well though. They are stronger essential oils and will give a more effective blend.

This particular blend of oil is a very strong skin irritant and you do need to make sure it is thoroughly mixed. Clove oil can actually be caustic* (burning). Mix 1 part of the entire mix with at least 10 parts alcohol. Leave in the alcohol overnight. Then mix with the distilled water.

Make sure you use amber bottles or opaque bottles. These aren’t just for decoration, but to make sure that the sunlight doesn’t break down the molecules in the essential oils and cause them to be inactive.

Personally instead of an alcohol spray, I’d rather mix a few drops of those essential oils into a perfume free hand lotion. The cream will still be antiseptic and antiviral but not so harsh on your hands, especially during winter.

*The Directory of Essential Oils – Wanda Sellar