The following operations change the class or type of distilled spirits and therefore require formula approval under § 5.192: Provided, That, TTB may exempt categories of distilled spirits products from specific regulatory formula requirements upon a finding that the filing of a formula is no longer necessary in order to properly classify the finished product:

(a) The compounding of distilled spirits through the mixing of a distilled spirits product with any coloring or flavoring material, wine, or other material containing distilled spirits, unless TTB has issued public guidance recognizing that such ingredients are harmless coloring, flavoring or blending materials that do not alter the class or type pursuant to the standards set forth in § 5.155;

(b) The manufacture of an intermediate product to be used exclusively in other distilled spirits products on bonded premises;

(c) Any filtering or stabilizing process that results in a distilled spirits product's no longer possessing the taste, aroma, and characteristics generally attributed to the class or type of distilled spirits before the filtering or stabilizing, or, in the case of straight whisky, that results in the removal of more than 15 percent of the fixed acids, volatile acids, esters, soluble solids, or higher alcohols, or more than 25 percent of the soluble color;

(d) The mingling of spirits that differ in class or in type of materials from which made;

(e) The mingling of distilled spirits that were stored in charred cooperage with distilled spirits that were stored in plain or reused cooperage, or the mixing of distilled spirits that have been treated with wood chips with distilled spirits not so treated, or the mixing of distilled spirits that have been subjected to any treatment which changes their character with distilled spirits not subjected to such treatment, unless it is determined by the appropriate TTB officer in each of these cases that the composition of the distilled spirits is the same notwithstanding the storage in different kinds of cooperage or the treatment of a portion of the spirits;

(f) Except when authorized for production or storage operations by part 19 of this chapter, the use of any physical or chemical process or any apparatus that accelerates the maturing of the distilled spirits;

(g) The steeping or soaking of plant materials, such as fruits, berries, aromatic herbs, roots, or seeds, in distilled spirits or wines at a distilled spirits plant;

(h) The artificial carbonating of distilled spirits;

(i) In Puerto Rico, the blending of distilled spirits with any liquors manufactured outside Puerto Rico;

(j) The production of gin by:

(1) Redistillation, over juniper berries and other natural aromatics or over the extracted oils of such materials, of spirits distilled at or above 190 degrees of proof that are free from impurities, including such spirits recovered by redistillation of imperfect gin spirits; or

(2) Mixing gin with other distilled spirits;

(k) The treatment of gin by:

(1) The addition or abstraction of any substance or material other than pure water after redistillation in a manner that would change its class and type designation; or

(2) The addition of any substance or material other than juniper berries or other natural aromatics or the extracted oils of such materials, or the addition of pure water, before or during redistillation, in a manner that would change its class and type designation; and

(l) The recovery of spirits by redistillation from distilled spirits products containing other alcoholic ingredients and from spirits that have previously been entered for deposit. However, no formula approval is required for spirits redistilled into any type of neutral spirits other than vodka or for spirits redistilled at less than 190 degrees of proof that lack the taste, aroma and other characteristics generally attributed to whisky, brandy, rum, or gin and that are designated as “Spirits” preceded or followed by a word or phrase descriptive of the material from which distilled. Such spirits may not be designated “Spirits Grain” or “Grain Spirits” on any label.