Place raisins into a bowl. Pour ¾ cup boiling water over raisins and Set aside. (You are allowing them to steep while you make the rest of the extract.)
Place half-gallon of water into pot over medium heat.
Place the sassafras root bark into tea bags or closely woven cheesecloth and tie with cooking string. Add it to the half-gallon of water. You can add it loosely into the pot but then you have to strain it several times through a fine mesh strainer.
As the water heats, stir in the sugar slowly. Don't dump it all at once.
Simmer uncovered for 40 minutes.
Remove from heat and remove sassafras.
Strain the raisin water into the brew pot.
Allow to sit for 30 minutes.
When it is cooled you can use your extract, storing extra in the fridge to use again. Try to use within 2 months.