OOAK Table Tennis Forum

My friend just received his Rakza 7 and Rakza 7 Soft, but surprisingly they were both slightly domed from out of the package. It has been a few days now and the dome has increased. Is this normal?

Yes that's normal, I see this all the time, nothing to worry about.

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That's not "dome", that's "dish". Dome is what you get when you apply booster or speed glue to the sponge, it curls towards the top sheet. Old sheets often develop dish, I think it's because the sponge side shrinks. Probably exacerbated by the loss of boosting compounds from the sponge over time in the case of factory boosted sheets, er, Tensors. There was a certain Chinese sheet that was notorious for excessive dish.. I forget what it was, exactly, but it was so bad on one particular sheet I ended up with a crease in the top sheet after applying it. I ended up applying booster to the sponge to flatten it out before re-applying it.
As Haggis says, it's normally not a problem, however I can't help but think it works the opposite of boosting.. when you apply it to the blade you force it flat, so you are stretching the sponge and compressing the topsheet, which is the opposite of what you want.

Iskandar

In this case I'm sure it's not because the sheets are 'old', I think it's temperature related. I suspect it either happens in the factory if the topsheet and sponge were not at the same temperature when glued together, or it's simply that the sheet comes from a region where the temperature is quite different, and the different temperature expands the topsheet and sponge differently, causing a dome/dish.
I glue a lot of bats, and I see this regularly on some brand new sheet, and I'm sure the rubbers are fresh from the factory (some rubbers have a 'manufacture date' on them on.

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OOAK Table Tennis Shop | Re-Impact Blades | Butterfly Table Tennis bats
Setup1: Re-Impact Smart, Viper OX, Victas VS 401 Setup2: Re-Impact Barath, Dtecs OX, TSP Triple Spin Chop 1.0mm Setup3: Re-Impact Dark Knight, Hellfire OX, 999 Turbo
Recent Articles: Butterfly Tenergy Alternatives | Tenergy Rubbers Compared | Re-Impact User Guide

I agree it's not always because the sheets are old. Do you notice that certain sheets are prone to it, or is it a random thing? I remember now - almost every sheet of Yasaka ZAP (no longer being sold) had "dish" to varying degrees - the really bad sheet had the softest of the sponges they offered at the time. If I recall correctly CJ8000 also had this problem.

Iskandar

Yes, certain sheets are definitely prone to. I never see it in rubbers like Bluefire, Tenergy, Tibhar evolution series, but for the Rakza series it seems not uncommon. Nothing wrong with the Rakza series of rubbers though, they're very good.

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OOAK Table Tennis Shop | Re-Impact Blades | Butterfly Table Tennis bats
Setup1: Re-Impact Smart, Viper OX, Victas VS 401 Setup2: Re-Impact Barath, Dtecs OX, TSP Triple Spin Chop 1.0mm Setup3: Re-Impact Dark Knight, Hellfire OX, 999 Turbo
Recent Articles: Butterfly Tenergy Alternatives | Tenergy Rubbers Compared | Re-Impact User Guide