As you rub the wool on the board the ribbed surface accelerates the felting process.
Curved grooves allow soapy water to flow as you rub.
Try making a ball to get a feel for felting:
Take a handful of carded wool, pour over it a mixture of hot water
(as hot as you can handle) and detergent. Soap powder can be used
instead of detergent, but dissolve the powder well in the hot water
first. Rub the wet wool between you hands to form a ball, and continue
squeezing and rubbing until you have a solid ball of felt. It is
surprising how much wool goes into a small ball. Experiment with layers
of different colors of wool. Completely cover the entire ball with each
felted color, before adding the next layer. The ball can be cut to
expose these layers. Rinse the ball in cold water, then hang out to dry.
When in stock, it ships from our shop in Maine. When out of stock (backordered) it will ship from Ashford USA