How to Make Nitrocellulose or Flash Paper

If you're a chemistry enthusiast with an interest in fire or history (or both), you probably ought to know how to make your own nitrocellulose. Nitrocellulose is also known as guncotton or flashpaper, depending on its intended purpose. Magicians and illusionists use flash paper for a fire special effect. The exact same material is called guncotton and may be used as a propellant for firearms and rockets. Nitrocellulose was used as a film base for movies and x-rays. It may be mixed with acetone to make nitrocellulose lacquer, which was used on automobiles, aircraft, and musical instruments. One unsuccessful use of nitrocellulose was to make faux ivory billiard balls. The camphored nitrocellulose (celluloid) balls would sometimes explode upon impact, producing a sound much like that of a gunshot. As you might imagine, this didn't go over well in gunslinger saloons with pool tables.

It's unlikely you will want to make your own exploding billiard balls, but you might want to try nitrocellulose as a model rocket propellant, as flash paper, or as a lacquer base. Nitrocellulose is extremely easy to make, but be sure to read through the instructions carefully before proceeding. As far as safety goes: Any protocol which involves strong acids should be performed by qualified persons wearing proper safety gear. Nitrocellulose cannot be stored for long periods of time, as it gradually decomposes into a flammable powder or goo (which is why many old films have not survived to the present day). Nitrocellulose has a low autoignition temperature, so keep it away from heat or flame (until you are ready to activate it). It does not require oxygen to burn, so once it ignites you cannot put out the fire with water. With all that in mind, here's how you make it.

Nitrocellulose Materials

Christian Friedrich Schönbein's procedure has been widely used. It calls for 1 part cotton to 15 parts acid.

• concentrated nitric acid
• concentrated sulfuric acid
• cotton balls (almost pure cellulose)

Nitrocellulose Preparation

1. Chill the acids below 0°C.
2. In a fume hood, mix equal parts nitric and sulfuric acid in a beaker.
3. Drop cotton balls into the acid. You can tamp them down using a glass stirring rod. Don't use metal.
4. Allow the nitration reaction to proceed for about 15 minutes (Schönbein's time was 2 minutes), then run cold tap water into the beaker to dilute the acid. Allow the water to run for a while.
5. Turn off the water and add a bit of sodium bicarbonate (baking soda) to the beaker. The sodium bicarbonate will bubble as it neutralizes the acid.
6. Using a glass rod or gloved finger, swirl around the cotton and add more sodium bicarbonate. You can rinse with more water. Continue adding sodium bicarbonate and washing the nitrated cotton until bubbling is no longer observed. Careful removal of the acid will greatly enhance the stability of the nitrocellulose.
7. Rinse the nitrated cellulose with tap water and allow it to dry in a cool location.

Shreds of nitrocellulose will burst into flame if exposed to the heat of a burner or a match. It doesn't take much (either heat or nitrocellulose), so don't get carried away! If you want actual flash paper, you can nitrate ordinary paper (which is primarily cellulose) in the same manner as cotton.

Chemistry of Making Nitrocellulose

Nitrating cellulose proceeds as nitric acid and cellulose react to produce cellulose nitrate and water.

3HNO₃ + C₆H₁₀O₅ → C₆H₇(NO₂)₃O₅ + 3H₂O

Sulfuric acid is not required to nitrate the cellulose, but it acts as a catalyst to produce the nitronium ion, NO₂⁺. The first order reaction proceeds via electrophilic substitution at the C-OH centers of the cellulose molecules.

Sources

• Braconnot, Henri (1833). "De la transformation de plusieurs substances végétales en un principe nouveau." [On the transformation of several vegetable substances into a new substance]. Annales de Chimie et de Physique. 52: 290–294.
• Pelouze, Théophile-Jules (1838). "Sur les produits de l'action de l'acide nitrique concentré sur l'amidon et le ligneux." [On the products of the action of concentrated nitric acid on starch and wood]. Comptes Rendus. 7: 713–715.
• Schönbein, Christian Friedrich (1846). "Ueber Schiesswolle" [On guncotton]. Bericht über die Verhandlungen der Naturforschenden Gesellschaft in Basel. 7: 27.
• Urbanski, Tadeusz (1965). Chemistry and Technology of Explosives. 1. Oxford: Pergamon Press. pp. 20–21.