OMR sheets are the printouts containing circles or bubble or box which is filled by the candidate as an answer using blue or black pen or pencil. The thickness of the paper does not affect the OMR process as because reads the image of the sheet and thickness of paper has nothing to do with it.
Thick paper is not crucial in the new OMR Sheet Reading Software Technology. Thickness of ordinary white paper that we use in our laser printers ranges from 60-80 GSM is OK.
The scanned image of the OMR answer sheet is required for scanning by the Addmen OMR sheet scanning software. Therefore the thickness of the paper does not affect anything.
Typical 70 gsm A4 paper that we use in our laser printers and scanners can be utilized in OMR sheet printing. It is normally accessible in the market.
Both thin and thick paper can be used.
Use white paper only.
18"x23" size paper can utilized for offset printing 4 sheets together.
The earlier technology was weak in many aspect therefore thick paper was used. The technology depended very much on the printing, cutting and scanning in order to get the accurate result. So thick was used to avoid damage from moisture and stretching because of pull exerted by the scanner roller. Hence the use of thick paper was necessary.
If you specifically want to use thick paper, then you can use it, but there is not any compulsion on using thick paper only. Nowadays some sheets are made up of thick paper, the reason behind that might be different. If you have to use thick paper, then you can use thick paper of 90-105 gsm but ideally it is not required.
Thick papers are used only if the user wants to keep the OMR sheet safe from damage with regards to handling by the candidate and examining staff. Thick can also be used, if the OMR sheet has to be transported long distance and it has to be stored for longer time.