I think I read a cup but that's getting expensive! But it's supposed to help with musty laundry odors. My washer is a small stacking unit so I'd use much less.
@Don Alaska Not certain how it works, but "denatured" Ethanol, that is, laced with Methanol, removes the restrictions imposed by taxation for consumption purposes. Possible maybe to distill alky already having Methanol added to it........BTW, I recall reading that it is quite difficult to obtain 100% Ethanol, expensive. Frank
The methanol is supposed to make it undrinkable, but I have known people to drink anything from after-shave to Listerine, so I don't think it is completely unpalatable. "Pure" ethanol is difficult to make and only useful for chemical uses. In order to get a distillation purity above 92%, there has to be something added to it to separate the last two percent from the water that is automatically carried with it through the distillation--I think benzene is normally used. That leaves trace amounts of residual benzene in the final product and is not recommended for consumption. Anyone who needs more than 184 proof alcohol REALLY has a problem!
Inexpensive white distilled vinegar can be used in the laundry to whiten, brighten, reduce odor and soften clothes without harsh chemicals. It is safe to use in both standard and high-efficiency washers and is beneficial to septic tanks and the environment. The acetic acid in distilled white vinegar is so mild that it will not harm washable fabrics; yet is strong enough to dissolve residues (alkalies) left by soaps and detergents. Adding just 1/2 cup vinegar to the final rinse will result in brighter, clearer colors. If using an automatic dispenser, add the distilled white vinegar to the fabric softener dispenser or add the vinegar manually at the beginning of the rinse cycle.
You read correct, 100% pure alcohol is not possible outside of super fancy laboratories. I used to take Everclear (190 proof) and distill it multiple times to 98-99% pure, but could never get it any better.
I have always used Rex Creolina (https://www.ebay.com/itm/112644954113) for 95% of my household cleaning, just like my Granny did. Works great, and the smell is 'back to childhood'.
@Don Alaska The product commonly sold trade-named Everclear is 190 proof ethanol, 95% alky, hopefully 5% water. If it contained benzine, I can't imagine it being sold for human consumption. Frank
Really pure alcohol is not sold for human consumption, that is why 190 proof stuff is as high as you can buy in a liquor store. Pure alcohol is for reagent purposes only, and I believe it is quite expensive.
Back in the day (like twenty or thirty years ago) I seem to recall it also required some sort of license to purchase.