Nobody Doesn’t Like Molten Boron

Nobody Doesn’t Like Molten Boron

Here’s an excerpt from my new book, The Practical Pyromaniac. It’s a bit different than a lot of the other projects because it deals with making things NOT catch on fire. It’s a pretty simple chemistry project. By the way, it makes paper fire resistant, not fire proof.

How to Make Boronized Fireproof Paper

Screen capture from Futurama

“Boronized” paper has been treated with a combination of boron salts that inhibits burning. Important papers can be treated in this fashion to give them a greater likelihood of surviving a fire.

YouTube player


  • 3 1/3 ounces boric acid powder. Although boric acid is used as roach killer, it is relatively safe to handle and is often available in hardware stores or online.
  • 4 ounces borax
  • ½ gallon hot water
  • Large mixing bowl
  • Spoon
  • Shallow tray (large enough to soak the paper)
  • Cotton paper (also known as rag paper, available at stationery stores)
  • Long-handled lighter or fireplace matches

1. Mix the boric acid powder and borax in one-half gallon of hot water in the mixing bowl. Stir until the chemicals are completely dissolved.
2. Pour the solution into a shallow tray. Carefully place a sheet of rag paper in the tray, saturating it thoroughly. Remove the paper, allowing the excess solution to drain back into the tray. Hang the paper to dry.
3. When dry, test a small piece of the paper by holding a match to it. The paper will turn black but not ignite and burn.

The fire resisting properties of boron were first examined by the French scientist Joseph Gay-Lussac in the early 19th century. He found that fire does not occur if air can be prevented from reaching the surface of organic materials by chemically coating the material’s fibers. Silicates and borates are well suited to the task of rendering organic fibers flame resistant. The normally flammable material calcinates, that is, turns it to char or black powder, but does not actually go up in a flame.

Discuss this article with the rest of the community on our Discord server!
William Gurstelle

William Gurstelle is a contributing editor of Make: magazine. His new book, ReMaking History: Early Makers is now available.

View more articles by William Gurstelle


Ready to dive into the realm of hands-on innovation? This collection serves as your passport to an exhilarating journey of cutting-edge tinkering and technological marvels, encompassing 15 indispensable books tailored for budding creators.

Escape to an island of imagination + innovation as Maker Faire Bay Area returns for its 15th iteration!

Buy Tickets today! SAVE 15% and lock-in your preferred date(s).