當曬版機在正常的抽氣時間內抽氣，操作人員發覺抽氣時底版與玻璃板之間殘留部分氣體，或聚或散在那里游動，而抽氣機就是抽不盡。這種情況下，操作人員就可以采用拍擊法，即以所用的力度以拍不碎玻璃板為適中，在曬版機一邊抽氣的情況下，操作人員一邊對準空氣的集中區拍擊玻璃板的上表面，盡可能使殘余的空氣散開，不聚在一起。
When printing machine in normal extraction time, extraction, the operator found extraction parts between the blank and glass plate, a gas or gathering or swimming there, and the pump is pumping. This case, the operator can adopt slapping method, namely with the strength to take no broken glass for moderate, in the case of plate burning machine side suction, operators and clusters of quasi air blows on the surface of the glass plate, as far as possible make the residual air out, don't get together. 
最好是緊跟著擴散的空氣后面去拍玻璃板，盡量使它們向四周擴散，這樣再加上抽氣機的作用，空氣很快就能被趕出底片的范圍，可以起到事半功倍的作用。千萬不能跑到擴散的空氣前面去拍擊玻璃，這樣會使剛拍散的空氣又重新聚集到一起來。
It is best to follow the spread of the air to take glass behind, try to make them around to spread, this effect, coupled with the pump air could soon be out of the scope of the film can have the effect of get twice the result with half the effort. Don't run to the diffusion of air to pat in front of the glass, it would make just made of air come together again. 
如果按正常的順序去拍擊仍不能達到目的，最好是能延長抽氣時間，這樣也可以得到滿意的結果。況且現在的曬版機多為程控式，一般情況下，進行二次抽氣是不會影響到整個制版過程的，這樣可以使操作人員有充足的時間去拍擊。
If in normal order to pat still cannot achieve a goal, it is best to extend the time of extraction, it also can get satisfactory results. Besides SPC printing-down machine than it is, in general, the second extraction will not affect the whole process of plate making, so that we can make the operation personnel have enough time to pat. 
出現這種類似情況，主要原因是底片面積較大，操作人員在放底片的時候沒有檢查一下底片與PS版的正面是否貼緊。有時底片是拼在片基上的，這樣也會使它們之間產生一定的空隙，這種情況也會造成上面所述現象，其處理的辦法與上面所講類同。
Appear this kind of similar situation, the main reason is that the film area is larger, the operator didn't check in a film and PS version of the film whether positive against. Film is sometimes spell on the base, it also can make produce certain gaps between them, this kind of situation will cause the above phenomenon, its processing method and the above brand affinity.