Details(XTG) Extreme Thickening Glue by Paul Mitchell is a strong hold finishing glue for short hair styles. (XTG) Extreme Thickening Glue is fantastic for spikes and extreme hair styles where a dramatic look is required for a long period of time. Hair even becomes thicker and great texture is achieved. Rub a small amount of (XTG) into the hands and activate. Work quickly into the hair to get the best results.