OOAK Table Tennis Forum

A rubber is often dished or domed from side to side but not from top to bottom (or the other way around). Whatever the resulting effect of stretching or compression of the topsheet, if any, wouldn't this effect be asymmetrical then? Have you ever observed that in the performance of the mounted rubber?

I've only seen this happen with really over-boosted sheets (where it curls up into a burrito). Not really sure what is happening but I suspect it's the rubber sheet rolling up in the direction of least resistance, rather than asymmetric/unidirectional expansion.

Iskandar

As I said: "Whatever" happens to "the topsheet", it happens *more in one direction than in another*.

Probably has to do with the alignment of the pips. Think e.g. Sriver L vs Sriver S - the pips align differently (by 90 degrees), so I guess one will dome in one direction (if you'd speed glue it) and the other in the other direction. In other words, direction of dome depends on whether pips are in rows or in columns.

When I've boosted rubbers such that they curl heavily, I've noticed that it's just as easy to get a top/bottom curl if you just nudge it that way; so definitely not like the rubber is only able to bend one way. As mentioned above, it's probably pip structure is such that when that a slight dome has a tendency to curl side to side.

As I've said, you see this usually when you've induced an extreme amount of expansion into the sponge. As you note - if you unroll the sheet and "nudge" it in the opposite direction you can get it to roll up the other way. I think what's happening is that when you have a small amount of sponge expansion, the rubber will dome (in two directions) but if the sponge expansion is greater, it would rather roll up in one direction or the other because this relieves the most amount of stress. If the sponge has expanded so much it causes the rubber to roll up like a burrito, the burrito is incapable (due to the extreme curl) of curling in the other direction.

I can't ever recall seeing a rubber "burrito" in the old days of VOC speed glue - the domes could be fairly radical, but the rubber would never get to the point you can achieve with modern boosters. In the old days the rubber would be forced onto the blade in the domed condition, these days we wait for the dome to subside or the rubber won't stick.

There are probably some people here wondering what a "burrito" is... have they made it to Australia yet? (Hint: Watch that "Battleships" movie.. there's a chicken burrito in it.)

Iskandar