There is no set maximum thickness that TotalBoat FixWood epoxy putty can be applied, however, it is encouraged to apply FixWood in stages when filling voids deeper than 1". This ensures ample working time, as like other epoxy products, the larger the volume, the faster it will cure. FixWood has extremely low shrinkage, but when applied too thickly, could potentially crack as it hardens.
For best results with thick applications, allow 6 hours between stages, and sand lightly with 80-grit sandpaper in the area where the next application will go, before applying another layer of Fixwood. A general risk of thick applications of FixWood is that it can become hard but brittle if applied too thickly, regardless if it was applied in stages.
Exotherm and excessive heat generation should not be a notable issue for applications of this thickness.