Intumescent coating is an insulating system designed to decrease heat transfer from a fire to the structure that is being protected so that the structure can maintain it's integrity within one to three hours for evacuation process. Intumescent coating reacts under the influence of heat by swelling in a controlled manner to many times it's original thickness and producing a carbonaceous char which is an insulating layer for the steel substrate. This study focus on the char morphology and of expandable graphite based intumescent coating using zinc borate as an additive. The Intumescent coating composition contains expandable graphite (EG) as a carbon source, ammonium polyphosphate (APP) as acid source, melamine (MEL) as blowing agent and zinc borate as additive, bisphenol A as epoxy resin and polyamide amine as hardener. The physical properties or morphology is investigated using FESEM after fire test. Formulation was prepared with different ratio of epoxy and hardener to investigate the best ratio for better bonding between intumescent coating and steel substrate. Graphite size 300 μm is used as it gives better expansion thus promotes adhesion. Coating ZB4 with high percentage of zinc borate and epoxy ratio2:1 gives good expansion as well as excellent adhesion.