This is an advance technique. It is recommended that you have experience and are comfortable with mixing and modifying plaster before attempting a cast repair..
Whether you are stripping the AFO positive cast or simply working on the fabrication of an AFO, the toe/forefoot region of the cast is highly susceptible to breaking. When this happens, you can reattach the foot with the help of plaster.
First you will need to use a sanding tool to mar the surface of the break.
You will also need to drill multiple large holes through the broken surface into the cast.This is to increase the surface area for the fresh plaster to bind onto
Now you will need to apply thick, wet plaster to both broken surfaces. Depending on how damp the cast is, you will need to wet both surfaces to prevent the cast from sucking out the moisture of the fresh plaster.
Once the surface is sufficiently damp, apply the fresh plaster and attach the broken pieces together.
Once the new coat of plaster cures, the broken pieces will stay attached until the end of the fabrication process. For added security, you may add additional plaster around the break, but make sure to stay away from the trimlines to avoid adding bulk to the cast.
A plaster buildup is added outside the trimlines (the dorsal section of the ankle in this example) to further strength the repair.