3D printing is a very flexible process to design various objects of original shapes. Previous works highlighted the elaboration of new multi-materials composed of an original sandwich structure made of ethylene vinyl acetate copolymer containing 30 wt.-% of aluminum trihydroxide in which a hydrogel phase made of agar and vermiculite was incorporated. This original material revealed an extremely low heat release rate (with a reduction of 86% and 64% as regard peak of heat release rate and total of heat release, respectively, when compared to the same sample without hydrogel filling) during its heat exposure at 50 kW/m2 using mass loss cone calorimeter test. However, the time to ignition of this material was not improved. This work consequently focuses on delaying time to ignition of this hydrogel sandwich 3D printed multi-material. Solution consists in depositing by pulsed DC magnetron sputtering a low emissivity thin coating on the exposed skin surface. This coating reflects most of the infrared rays responsible for heat absorption, and thus delays the ignition of the underlying material. The thermal resistance performances of this coated sandwich 3D printed multi-material were evaluated, and a mechanism of action was proposed to explain the dramatic enhancement of the properties.