I think all the people who recommend softer sponges to beginner players are often not considering the blade properly. If the blade you are using has a harder outer layer, then a soft rubber will make the grip on the ball so hard to achieve for a beginner player that creating a spin oriented stroke will be very hard because of the bottom out effect (the ball catapulting out from the wood before the rubber is able to grip on to the ball). I have this discussion with my coach, but I have given up on trying to tell him because he is the authority and this will break his whole system of thinking and coaching. There are slower blades which are designed to flex to accomodate chinese forehand rubbers with harder outer layers for beginner players. These blades would not do well with soft rubbers ... and for adult athletic beginners who are able to generate a lot of force, but dont have the sufficient technique to generate spin might actually benefit from playing with harder rubbers so that the sponge can compensate for their lack of ability in brushing the ball very thinly.
I have a chinese style bat, with very hard outer layer. What you said is true. This bat doesn't play well with bouncy soft rubbers. As a begginer I had a hard time to learn, because it was a rocket, even when everyone was telling me soft rubbers were slower. Today, I own another bat, with softer outer layer, and it goes well with many types of rubber, including the ones I was strugling with. Ps: The chinese bat I have, I experimented putting a hurricane 3, and it makes a lot of sense, because this type of racket compensates the lack of bouncyness of the rubber, so is not that slow on short game, and when doing top spins and fast swings, the rubber is fast.
39 the degree of hardness, 39 is softer than 40. Sponge thickness and wood hardness also matter. The thinner the rubber, the less speed and spin you will have but the more control. All thinks being equal we recommend thicker rubbers, 2.0 or greater. But note there are players who prefer the thinner rubbers for more control.
