70% Alcohol Solution Recipe using 91% Isopropyl Alcohol
Alcohol surface sprays can be useful for cleaning routines when they are mixed, labeled, stored, and used correctly. This recipe explains how to make a 73% alcohol surface spray using 91% isopropyl alcohol and water.
This recipe is for hard, nonporous surfaces only. It is not a hand sanitizer recipe, and it should not be used on skin, pets, food, wounds, toys that may be mouthed by children, or surfaces that are not compatible with alcohol.
Culinary Solvent does not sell isopropyl alcohol. For a surface spray recipe using ethyl alcohol instead, view our preferred disinfectant spray recipe using 200 proof ethanol.
70% Alcohol Solution Recipe Using 91% Isopropyl Alcohol
Recipe: 73% Alcohol Surface Spray Using 91% Isopropyl Alcohol
This recipe starts with 91% isopropyl alcohol, sometimes called rubbing alcohol. Mixing 8 fl oz of 91% isopropyl alcohol with 2 fl oz of water creates 10 fl oz of finished alcohol surface spray at approximately 72.8% alcohol by volume, commonly rounded to 73%.
The most important part of this recipe is accurate measuring. If too much water is added, the finished alcohol percentage will be lower than intended. Do not guess or “eyeball” the recipe.
Before You Start
Clean first, then apply alcohol surface spray. Alcohol works best on surfaces that are already free of visible dirt, grease, dust, and grime. If a surface is visibly dirty, clean it first with soap and water or a surface-safe cleaner before applying the alcohol solution.
Alcohol is flammable. Mix, store, and use this spray away from flames, sparks, pilot lights, cigarettes, candles, hot surfaces, and other ignition sources. Use in a well-ventilated area and allow treated surfaces to dry fully before using appliances, electronics, or anything that may create heat or sparks.
Do not mix isopropyl alcohol with bleach, ammonia, vinegar, hydrogen peroxide, commercial cleaners, or other disinfectants. Mixing cleaning chemicals can create dangerous fumes or reduce product effectiveness.
Alcohol may damage some surfaces, including certain plastics, acrylic, painted finishes, finished wood, leather, natural stone, electronics, and coated screens. Test a small hidden area first and follow the surface manufacturer’s cleaning instructions when available.
Ingredients
- 8 fl oz 91% isopropyl alcohol
- 2 fl oz clean water
Step-by-Step Instructions
Step 1: Add 8 fl oz of 91% isopropyl alcohol to a clean spray bottle or clean mixing container.
Step 2: Add 2 fl oz of clean water.
Step 3: Close the container and shake gently to combine.
Step 4: Label the bottle clearly as “73% Isopropyl Alcohol Surface Spray.” Include the date made and the word “Flammable.”
Congratulations!
Your 73% isopropyl alcohol surface spray is finished and ready to use on compatible hard, nonporous surfaces.
How the Alcohol Percentage Is Calculated
The basic calculation is:
Pure alcohol volume ÷ total batch volume × 100 = final alcohol percentage
For this recipe:
8 fl oz × 91% = 7.28 fl oz pure alcohol
7.28 fl oz pure alcohol ÷ 10 fl oz total batch × 100 = 72.8%
This is commonly rounded to 73% alcohol by volume. If extra water or other ingredients are added, the final alcohol percentage will be lower.
How to Use Isopropyl Alcohol Surface Spray
Spray the clean, hard, nonporous surface until it is visibly wet. Allow the surface to remain wet before wiping or letting it air dry. If the surface dries too quickly, reapply more solution so the surface stays wet long enough for proper contact time.
Do not spray into the air. Do not use as a room spray, body spray, linen spray, hand sanitizer, or food-contact sanitizer unless you are following the rules and instructions that apply to that specific use.
Do not spray directly into electronics, outlets, switches, appliances, or open flames. If cleaning electronics, follow the device manufacturer’s cleaning instructions.
Storage and Shelf Life
Store finished alcohol spray in a tightly sealed container away from heat, flames, sparks, and direct sunlight. Keep the bottle closed when not in use. Alcohol can evaporate if the bottle is left open, and evaporation may lower the alcohol concentration over time.
Follow the storage and disposal directions on the original isopropyl alcohol product label. If the bottle has been left open, stored near heat, contaminated, or is no longer clearly labeled, discard it safely and make a fresh batch.
Can This Recipe Be Sold or Distributed?
This recipe is intended for small personal-use batches only. Disinfectants sold or distributed in the United States may be regulated by the EPA and must meet applicable labeling, registration, and use-direction requirements. Do not use this home recipe for commercial manufacturing, resale, public distribution, or regulated disinfectant claims.
Why This Recipe Is Different From Ethanol Surface Spray
Isopropyl alcohol and ethyl alcohol are different alcohols. Both are used in cleaning and disinfecting products, but they are not the same ingredient. Isopropyl alcohol is not food grade alcohol and should never be swallowed.
Culinary Solvent does not sell isopropyl alcohol. For a surface spray recipe using Culinary Solvent’s 200 proof food grade ethanol, use our 200 proof ethanol disinfectant spray recipe.
