Examples from the Web for unsalted
These work well enough that I have two sitting on the counter at all times: one for unsalted, and one for salted.
When the food did make it to the table, it was apparently “pale and unsalted,” at best, and at worst, “one chaotic mess.”Guy Fieri Battles Scathing New York Times Review by Pete Wells|Katie Baker|November 16, 2012|DAILY BEAST
Ladies were compelled to dispense with salt in their culinary operations; even the butter was unsalted.The Iron Furnace|John H. Aughey
It was with unsalted butter it was used, but I don't know what the words were.
At the time I did not know that "green" was a term used to denote "fresh" or "unsalted."A Mind That Found Itself|Clifford Whittingham Beers
If an unsalted shortening is used take slightly less and add a small quantity of salt.New Royal Cook Book|Anonymous
To make soft pomatum, beat half a pound of unsalted fresh lard in common water, then soak and beat in two different rose-waters.