Two 11” x 1” wide strips of printer paper were cut. One strip was soaked in the flame retardant (FR) solution for 5 minutes to ensure total saturation of the paper fibers. The other strip was used as an untreated control. The treated sample was removed from the solution and hung up to dry overnight. The untreated control was kept in close proximity to the treated sample to ensure that both samples were exposed to the same environment and that the only difference was the Borax treatment.
After drying overnight, the treated sample was cut into 3 roughly equal sections and the control was treated in the same manner.
Each specimen was then gripped in along handled pair of needle nosed pliers and lit with a match.
In every case the untreated specimens were completely consumed by the flame while the treated specimens smoked, generated a char and then self extinguished (right 3 specimens). Below is an image of the final results. In this image, I was only able to transfer the ash of one untreated control sample ((left side of the image) to the cardboard for the photograph, the other two controls disintegrated.
This works because the borax forms a primitive form of glass as it is exposed to the heat of the flame. The glass acts as an insulator, protecting the paper fibers from the heat and allowing them to char instead of burn. The char acts as an additional insulator. Eventually there is not enough heat to support combustion and the fire goes out.