The back glue surface is grainy, which is not only not a quality problem, but also due to filling sponge glue.
Wet father's answer: no quality problem!
After filling with oil and glue, after expansion of sponge, surface of rubber is subjected to a tensile expansion force, so that particles under surface of rubber can be seen in natural physical phenomenon of rubber surface. Generally, we will be grain filled rubber or fish scale rubber surface (divided into small fish scale and large fish scale).
Hurricane 3 shown above with high density hard sponge. The pores of sponge are very small and density is high. Typically, this graininess appears on surface of rubber, indicating that filling with oil and glue is relatively sufficient.
After oil lubrication, expansion of sponge causes rubber surface to expand and rubber surface to stretch so that particles underneath can be seen through rubber surface.
We often see rubbery surface of some professional athletes with this graininess because they are completely oiled and sponge is stretched. Professional athletes like to buy thin sponges with a high degree of protection, such as 41°Lan Guokuan with a thickness of 2.1mm.
ITTF stipulates that thickness of sponge+rubber should not exceed 4.0mm, and professional athletes have relatively high demands on support and elasticity of sponge. Choosing a high-height pad can expand sponge by filling with oil at a later stage, and then apply inorganic adhesive as a base. The base layer after one layer adds elasticity.
Recreational golfers rarely use oil, and most of them still use organic glue, and swelling effect of organic glue can last no more than a few hours. Under normal conditions, graininess will be more likely.
The image above shows a biscuit shell. Compared with national set, rubber surface of shell will have greater strength, biscuit holes will be larger, and possibility of grit on rubber surface will be greater after lubrication.
So, golfers, don't be surprised when grit comes out in future, it means that you have stuffed it enough, and performance of this rubber can be brought to 100%.
Amateur golfers often ask this question, and when it comes up, they wonder if it's fake or if you have quality issues. To be honest, I am very tired, explanations of support service are useless, client does not believe at all and thinks that you are just nitpicking. Therefore, in near future, I will put together a Pingpong.com support team and answer all questions that golfers have that I have encountered. I also hope that most amateur players can get a deeper understanding of table tennis equipment.
Wet Father Guo Yunpeng
November 12, 2023