The cover is preferably turned between {TAIL ~ successive rotation processes} so that a clean side of {HEAD ~ the cover} is always directed to the substrate that is to be treated, whereas the side that has become contaminated from the previous rotation process faces away from the substrate and can be cleaned 
The cover is preferably turned between { TAIL ~ successive rotation processes } so that a clean side of { HEAD ~ the cover } is always directed to the substrate that is to be treated , whereas the side that has become contaminated from the previous rotation process faces away from the substrate and can be cleaned
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH