Sorry for necro, but can you develop this impact-first, tangential thing.
I'm going to assume you mean to ask me to explain, so sure:
This is exaggerated, in reality it's far more nuanced and the actual difference is not *that* pronounced, but:
Impact-first (generally for tacky rubbers):
Step 1, you hit the ball, driving it into the rubber and sponge. Your bat angle is open, your rubber surface and the ball's trajectory coming towards you make an angle between 60-90 degrees.
Step 2, with the ball driven into the sponge, you wipe with your bat, generating spin on the ball.
Step 3, the ball gets released off the rubber in a similar angle to its approach.
If you've ever played with a spinning-top toy, something that you wind a string around and then pull it swiftly to make the thing spin, that's what I imagine when I think of adding spin with a tacky rubber.
Tangential (generally for grippy, euro/jap rubbers):
Step 1, you hit the ball at a sharper angle, say between 45-60 degrees. This drives the ball into the rubber tangentially (so the pimples will bend to one side, forming a parallelogram between topsheet and sponge, instead of a rectangle.
Step 2, you wipe spin on the ball while keeping the angle the same.
Step 3, the ball gets released due to the rubber snapping back into shape, which catapults both spin and speed on the ball.
I think more of shooting a rubber band with your hands here, you stretch it to make the right angle and speed, and then release.
Now, as you can see, steps 2 and 3 aren't all that different. The main difference is whether you're (mainly) using mechanical grip and stretch to generate both your speed and spin (Euro, tangential contact), or you use the impact force to generate speed, and the tackiness to create spin (tacky, impact style contact).
You
can play impact-first with Euro rubbers, especially nowadays with sponges getting harder and harder. It's actually a very effective contact method with the evolution of the game after the plastic ball introduction. The game is more about speed and less about spin (again, exaggerated) so making solid impact will be a benefit.
You also
can play tangential with tacky rubbers. But it's not very effective and just
not going to develop a good game. Most tacky rubbers aren't made for mechanical grip, the harder topsheets don't stretch as much, and if your angle is too sharp for the speed of your swing, the ball will skid off with a
squeak (this happened to me a lot). My advice: if you want to play tacky rubbers, learn to use that impact-first style and never stop doing that.
Of course, it's
possible to switch from one style to the other. But this can take serious training hours, especially if you have lots of experience with one style. I tried switching to tacky rubbers for almost a year and while I think I have most of the basics down, muscle memory is still causing me to make silly mistakes in matches. When I put Euro rubbers back on, everything felt so much easier and natural that I decided to just drop it.
With tacky, I just can't get the angle right, my very spinny shots have too little impact and as a result, no speed. And my speedy shots aren't very spinny, so not dangerous. With euro rubbers I can make contact without thinking about it. But that's because I've always used euro rubbers, since before tensors existed.