Place oil, comfrey, and ginger into the top of a double boiler. Warm the oil on low for at least an hour. Be sure that the oil is just warming and not a full simmer. Strain the oil using cheesecloth, a metal sieve, or mesh produce bag.
Add cocoa butter and beeswax to the oil and stir until all is melted. You may need to return to heat to fully melt beeswax and cocoa butter. Add essential oils when mixture has cooled enough to touch.
Notes
Safety - Simply remove the rosemary essential oils and this salve is safe for children and women who are pregnant or breastfeeding.
Recipe by Scratch Mommy at https://scratchmommy.com/homemade-muscle-rub/