Urtication is the process of deliberately applying stinging nettles to the skin. The result of such treatment is an intense burning irritation, which is also visible as reddening. The effect is very similar to the warm feeling that comes just after the sharp pain of a whipstroke fades. While a whipstroke comparatively fades rapidly, the glow can last for hours.
As stinging nettles leave the skin very sensitive, further beatings are much more effective: A light spanking feels like a strap, a feather can feel like a brush, a light strap or flogger can blow their minds.