Endoscopic radiofrequency ablation has gained interest for treating abdominal tumors. The radiofrequency ablation electrode geometry largely determines the size and shape of the ablation zone. Mismatch between the ablation zone and tumor shapes leads to reoccurrence of the cancer. Recently, work has been published regarding a novel deployable multi-tine electrode for endoscopic radiofrequency ablation. The prior work developed a thermal ablation model to predict the ablation zone surrounding an electrode and a systematic optimization of the electrode shape to treat a specific tumor shape. The purpose of this work is to validate the thermal ablation model through experiments in a tissue phantom that changes color at ablation temperatures. The experiments highlight the importance of thermal tissue damage in finite element modeling. Thermal induced changes in tissue properties, if not accounted for in finite element modeling, can lead to significant overprediction of the expected ablation zone surrounding an electrode.