Magnesium “oil” isn’t actually an oil — it’s magnesium chloride dissolved in water.
So if you’re trying to add it to a salve (which is oil + wax only), it will separate. Water and oil won’t stay mixed without an emulsifier.
You have three options:
1️⃣ Keep it a true salve (no magnesium oil)
Infuse your comfrey + arnica into oil, strain, then make a normal balm with wax.
This will stay stable because it’s fully oil-based.
2️⃣ Make it a cream instead of a salve
If you want magnesium included, you need:
An emulsifier (e.g. Emulsifying Wax, BTMS, etc.)
A preservative (because magnesium oil = water phase)
Then it becomes a lotion/cream, not a salve.
3️⃣ Use magnesium flakes directly?
No — they won’t dissolve in oil. They must be dissolved in water first, which again means you’re making an emulsion product.
That separation you’re seeing isn’t failure — it’s chemistry.
Salves = oil only
Magnesium oil = water
Water + oil = needs emulsifier