History & evolution of rubber types in table tennis - A quick primer

[samatura]

Hardbat & sandpaper came first.

Sandpaper rackest were never approved for use ITTF & continue to be not approved.

Hardbat is basically short pips with no sponge. Only harbat was allowed in ITTF since inception.

I believe bare wood was approved for use as well but de-approved sometime in 80's. You cannot strike the ball with the wood side of your racket if you leave one side without any rubber.

Sponge was introduced in 1952

After that there were two types of rubbers.
One was the short pips as before but there was a sponge layer between short pips (also known as pips out) & the blade (the wood potion of the racket)
The pips part was now called the top sheet (So a rubber consists of two parts > top sheet & sponge)
Second one is known as inverted or smooth or reversed or pips-in rubber. This is the most popular rubber today. For this type of rubber, there is still sponge between wood & the top sheet is glued to the sponge by turning the top sheet & sticking the pips to the sponge , which gets glued to the wood part (blade) .
Not sure why the pips were needed for smooth rubber type (Why can't they just stick a smooth to sheet to the sponge. I am sure it was tried and may be the ITTF felt the pips were better for even smooth rubber)

Anti spin rubbers arrived in late 60's or early 70's after spinny smooth rubbers arrived in 50's.

Antispin rubbers were developed to handle the havey top spin (loops) created by smooth rubbers using chops

Long pips rubbers were also invented in mid 70s' for choppers to be able to handle the heavy top spin created by loop attackers

Super long pips arrived around 2018 to somewhat level the playing field in the 40+ plastic ball only era.