A carbonless sheet is an OMR sheet with 2 copies attached back to back. The first copy is relatively thick and is retained in the examination hall for checking and the second copy is a thin paper copy with a carbonless coating which the candidate can take home for reference. When the candidate fills a bubble on the sheet the pressure exhorted creates a black mark on the back copy. So the take home copy is an exact replica of the sheet submitted for evaluation. This method creates transparency and faith amongst candidates as the candidate who has got marks less than his expectation can raise a claim after validating with their copy of the answer sheet.
Using the carbonless OMR sheet allows the candidate to have an exact replica of what he has filled and so he can report if he finds any discrepancy in the result. At the same time it also safeguards the examination body from faulty of mischievous complaints.
The first part which is retained by the examining body for OMR Copy Checking is generally thicker while the second part taken back by the candidate for reference is generally thinner.
The total of 2 parts is 180 gsm. Generally the paper thickness is 105 gsm (first sheet) + 65 gsm (second sheet) + coating. In some cases paper thickness is 90 gsm + 90 gsm.
The second part has a chemical coating which becomes black with minor pressure exerted when the candidate fills the bubble on the first sheets with pen or pencil.
Both OMR Sheet copies are printed with 2 different colours so that the candidate does not take the wrong copy with him.
Addmen provide both 2 part and 3 part carbonless OMR sheets for the OMR Test Checking projects that we undertake. OMR Sheet cost depends on the quantity of Sheets to be printed, inclusion of unique numbering or barcode or litho code.
Carbonless OMR Sheets are very costly and procured only from special sources. Thus this process is generally not implemented in private exams. It is only implemented in sensitive government recruitment exams.