Defortify (or Fort stripping) is a status effect that removes the Fortify property off of Fortified Bloons. It was introduced into Bloons TD 6 with the introduction of Shattering Shells and Perishing Potions in Bloons TD 6 along with the Fortify property. It is part of the damage types family.
Defortify is represented on Bloons Wiki as , the upgrade icon for Perishing Potions in Bloons TD 6, which shows a bloons that was encased in a lead bloon having its armor eroded off. Strangely, it doesn't actually show the fortify band around the bloon eroding off and instead shows a lead bloon's armor being eroded off. The bloon-specific variant is Defortify Bloon. The blimp-specific variant is Defortify Blimp , the upgrade icon for Shattering Shells, since it clearly shows the fortify bands around the M.O.A.B. are being removed from the blimp.
When defortifying a bloon or blimp, its entire outer layer loses half of its health (or three-quarters in the case of Fortified Leads). In the case of Fortified MOAB-class stripped of Fortified properties, their descendants will lose the Fortified property too. The damage counter of the tower inflicting the defortification will go up to reflect the total lost HP from the bloons.
All towers require an upgrade in order to have the defortify property.