? How to make ideal soap bubbles? Here is the perfect recipe

When a child pours liquid from his toy to blow bubbles, it is often replaced by dish soap and… works less well. Is there a better recipe for making soap bubbles? The specialists in this question are the artists who manipulate the bubbles in their shows. One of them provided us with a widely used recipe to better understand the physical mechanisms behind it.

We had to identify which well-controlled experiment makes it possible to test the recipes. This experiment must be reproducible, i.e. give the same result when repeated several times in a row. We therefore worked at a temperature and a humidity (Humidity is the presence of water or water vapor in the air or in a substance…) of constant air. Indeed, these parameters are very important, because they modify the speed (Let’s distinguish 🙂 Ofevaporation (Evaporation is a smooth transition from a liquid state to a gaseous state. It’s different…) Of liquid (The liquid phase is a state of matter. In this form, matter is…). Soap bubbles are made up of a thin film of liquid that encapsulates air. If this film becomes too thin, the bubble bursts more easily. So the higher the evaporation rate, the faster the liquid evaporates, the thinner the film and the faster the bubble bursts.

We identified two different experiences. In the first we place a soap bubble on a surface (A surface generally refers to the surface layer of an object. The term a…) and we measure its duration. This allows you to measure the bubble stability for a recipe data (In information technology, a datum is an elementary description,…). In a second experiment, we immerse a plastic ring in a soapy liquid and always blow into it at the same speed thanks to a speed regulator. pressure (Pressure is a fundamental physics notion. You can think of it as a force reported…). We count the number (The notion of number in linguistics is dealt with in the article “Number…) of bubbles thus created.

The surprising result of our study is that the recipes that give bubbles that last a long time are not necessarily the ones that allow you to make a lot of bubbles. Good recipes are the result of a compromise. So, we know you have to put dish soap in it to make soap bubbles. It is he who contains the soap molecules. If you use a small amount, the bubbles last a long time, but are difficult to form. If you put too much, you can make lots of bubbles that pop very quickly. It is the compromise between these two Comments (Observation is the action of attentively following phenomena, without the will to see them…) which lead to Quantity (Quantity is a generic term of metrology (count, amount); a scalar,…) dish soap used by artists: 4% of volume (The volume, in the physical or mathematical sciences, is a quantity that measures the extension…) i.e. 40 ml of dish soap in 960 ml of water for the particular dish soap we studied.

It is then possible to add ingredients which improve both the stability and the ease of bubble formation. To have more stable bubbles, you can add 10% glycerol, i.e. 100 mL per 900 mL of mixed (A mixture is an association of two or more solid, liquid or gaseous substances…) dish soap/water. It is a liquid widely used in cosmetic (A cosmetic is a substance or mixture intended to be incorporated into…) because it preserves the products from drying by preventing the evaporation of the water contained in them. It is located in Pharmacy (The pharmacy (from the Greek φάρμακον/pharmakôn…). However, as explained above, one way to delay the bursting of the bubble is to reduce evaporation.

To make bubbles easier to make, we can add long molecules (called polymers) that will act like long threads inside the soap film. With guar gum, a food additive that allows you to gel preparations, you only need to add one gram. When the bubble is formed, the film on the plastic ring must deform to become a bubble. It then becomes very thin and the long strands will organize themselves parallel to the surface of the film. They will thus prevent it from breaking during its manufacture.

The recipe in a nutshell: Dilute 1 gram of guar gum in a little glycerin and add 40 ml of washing up liquid (choose a washing up liquid containing 15-30% anionic surfactants or double the dose, check on the product label) and 100 ml of glycerin. This preparation can be kept for a few days. At the last moment, add 860 ml of water to obtain 1 liter of solution.

This article is the result of a collaboration with bubbler artist Pierre-Yves Fusier and Laura Wallon.