SignificanceColloidal gels (solid particle networks formed by physical interparticle bonds) are found in materials spanning food and consumer products, coatings, and structural materials. Despite this ubiquity, we lack generalized theories to accurately predict the minimal conditions required for gelation. This is due both to the multiple mechanisms by which gels can form, and to the lack of unambiguous methods for determining where and when gels exist within a phase diagram. In this work, we develop an unambiguous method for determining the minimal conditions for gelation. The results unify different gelation mechanisms into a single framework, identify the importance of time in setting gelation behavior, and provide an outlook for using thermal processing to engineer the properties of colloidal solids.