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Name: Terria
Status: other
Grade: other
Location: TN
Country: N/A
Date: August 2006

Hello! I am writing because my children have an indoor room spray in mind that they would like to make. I (their mother) am not a chemist so I am really not sure how to mix the product. I have looked on several labels on different products and have noticed that denatured alcohol is an ingredient. Could you tell me what percent and how much denatured alcohol needs to be mixed with water to come up with a solution for safe use? They will also be adding a fragrant of their choice with this product for spraying in the air. Can you please help?


The word denatured, is referring to the removal of a specific property (in this case, its usefulness as a beverage), as opposed to changing the ethanol chemically. This is done in one of several ways, the most common consumer way being addition of methanol. Methanol is wood alcohol and is harmful to ingest. Getting methanol or ethanol on your skin is not harmful unless it is quite a lot for prolonged periods of time. The methanol content in ethanol is normally 10% or less and it will be further diluted with the water in your mixture.

If you have 100% denatured ethanol (meaning that there is no water added), then the addition of the ethanol to the water will be exothermic. This means that heat will be released and you should use caution when adding the chemicals together. There will not be a significant amount of heat being released--i.e. not enough to burn you or boil water--but the amount of heat released will increase with greater quantities of alcohol and water that are mixed. If you are simply filling a squirt bottle (~1-1.5 liters or so), then you can probably add the two liquids to each other over a 1 minute period and be more than fine. Adding it in small portions and waiting a several seconds is probably the best way to do this.

In general the solution you described is very safe and you should only consult poison control if the solution is ingested. One of the side effect of ingesting methanol is blindness and the cure is actually giving them ethanol to drink. The ethanol will flood the places in your body that the methanol is occupying and remove the blindness, but of course, this will get your kids drunk! Better drunk than blind. If the mixture is sprayed in the eyes, flush with water for 10 minutes and use eye drops afterward. Anyway, I do not say any of this to scare you, just to inform you. The solution should be at least as safe as Windex and should not be sprayed on things that can result in water damage (wood, drywall etc).

Your kids can also make smaller solutions and change the ratio of the ingredients to see what they like the best. Unless the solution is already very low in water content (less than 50%) try reducing the percentage of water (keeping the total volume the same) and then in another mixture try increasing the amount of fragrance. In a third you can decrease the amount of water AND increase the amount of fragrance. You can also increase the amount of water (if you have less than 70% or so) and try the same types of experiments. What you will want to measure (remember, measurement is the essence of an experiment) is the power of the initial scent and how long it lasts. The optimal being an initial scent that is not too powerful, yet lasts a long time. You can spray pieces of paper to compare the different solutions.

What I might expect to happen as you decrease the amount of water/increase the amount of alcohol, the scent will last a shorter time and might have a slightly more powerful initial scent. Though when you increase the water amount/decrease the alcohol, the initial scent should be weaker, but it should last longer. Increasing the fragrance to compensate might be the optimal solution, but you will have to do the experiment to find out. If you decide to make 100% solutions of alcohol or water, with fragrance, you should find out that alcohol is necessary to aid in the diffusion of the fragrance. While you might be able to smell the fragrance at a very close distance, you probably will not smell it from more than 6-12 inches away. Enjoy the time spent with your children!

Matt Voss

This is very difficult to answer: It involves "children" age unknown, and a mother who is not sure what she is doing. As far as "product safety" denatured ethanol can be purchased at any pharmacy, usually 20-30% water. I would be equally concerned about what "fragrant of their choice" is being added. Especially, since it appears that they are going to be spraying this around the house.

This is an exercise that should be using a published, tested procedure since the inquiry does not even specify what "safe use" means.

I would decline a recommendation.

Vince Calder

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