27 CFR §20.124

1. (a)Duplicating fluids and ink solvents under this general-use formula shall be made with alcohol denatured in accordance with S.D.A. Formula No. 1, 3-A, 3-C, 13-A, 23-A, 30, 32, 35-A, or 40-B, and
   1. (1)Shall contain, for every 100 parts (by volume) of denatured alcohol:
      1. (i)No less than 1 part (by volume) of n-propyl acetate, and no less than 10 parts (by volume) of one or any combination of isopropyl alcohol or methyl alcohol; or
      2. (ii)No less than 5 parts (by volume) of n-propyl acetate; and
   2. (2)May contain additional ingredients.
2. (b)Duplicating fluids and ink solvents are intended for use in the printing industry, shall not be sold for general solvent use, and shall not be distributed through retail channels for sale as consumer commodities for personal or household use.