There are many web pages I can find (random example here: https://grapecollective.com/articles/prohibitions-grape-bricks-how-to-not-make-wine) which post images of these bricks, indicating that the bricks existed, but not the specifics that there were direct prohibition-dodging instructions attached. It says you can add "Benzoate of soda" (Today we would call it sodium benzoate) to prevent fermentation, but it doesn't give the instructions which are obviously meant to encourage fermentation.
I can't find a single photo of one of these bricks with the claimed phrase.
There are of course images people have put together, like this one: https://pics.me.me/source-is-mentioned-in-our-blog-www-unbelievablefactsblog-com-during-prohibition-grape-4225356.png but obviously anyone can put that together in 5 minutes.
Was the specific disclaimer about not leaving the grape juice to ferment a real thing? I don't see why they would have both this disclaimer, AND the "add sodium benzoate" disclaimer to both avoid fermentation. Is it possible to debunk this? The ideal resolution to this would, of course, be to have a picture of the packaging of one of these bricks proving that it was real, but failing that, it would be nice if the origin of this myth could be identified.
Thank you!
The answer is very simple - the quoted instructions were made up post-fact (I was unable to find the original example unfortunately), but did represent the spirit of the instructions included in the wine bricks. Interestingly, even Beringer, where I've seen one of the wine bricks first-hand, repeats this claim of the instructions on their website, but it is not visible on the packaging that I saw.
Section 18 of the Volstead Act specifically says:
It shall be unlawful to advertise manufacture sell, or posses for sale any utensil, contrivance machine, preparation compound, tablet, substance, formula direction, or recipe advertised, designed, or intended for use in the unlawful manufacture of intoxicating liquor.
Therefore, instructions were required to be clear on how to prevent fermentation. No real instructions would have said "don't do this, or else it will turn into wine", or else they would have opened themselves to severe legal risk (employees of one of the largest wine brick producers, were arrested on at least one occasion). The instructions would explain very carefully what to do to prevent fermentation, but also give hints on what you actually needed to successfully ferment the grapes, for example this label.
Recipes for Vino Sano Grape Juice.
(a) PORT, SHERRY OR ANGELICA TYPE
Dissolve one Vino Sano Grape Brick in one gallon of water, and add two pounds of sugar (preferably corn sugar).
(b) RHINE, MUSCAT OR BURGUNDY TYPE
Dissolve one Vino Sano Grape Brick in one gallon of water, and add one pound of sugar (preferably corn sugar). Then add one small teaspoon full of U. S. P. benzoate of soda to prevent fermentation. You must also avoid the use of any kind of yeast, raising, etc., otherwise fermentation sets in. Pour liquid into a clean demijohn and let it stand in a warm place for about three weeks until it becomes clear. Keep dust out by placing a small wad of loose cotton in neck of demijohn. Air is the greatest enemy to grape liquid.
Note the instructions "to avoid yeast" provide hints on what to do, and the instructions after that (pouring the liquid into a clean demijohn, "keeping dust out with loose cotton", are all hints for successful fermentation. Generally, to ferment your own wine at home, the basic steps are:
Start with extremely clean equipment
Add crushed grapes (in this case, the brick)
Add yeast
Make sure there is enough sugar with a hydrometer (they provide instructions on exactly how much to add)
Cover the fermentation container with a cloth (to keep it clean but allow air out).
You can see how it matches the instructions above. I suspect as well that wild yeast was still on the grapes that were compressed into the brick, meaning it would spontaneously ferment unless you added the sodium benzoate.
All instructions I've unearthed reference stopping fermentation with sodium benzoate in different ways. I have not found a single reference otherwise.
While looking for further examples I discovered this blog entry which comes to the same conclusion I did.
