The OMR sheet requires the candidate or student to read the question and mark their answer on the sheet by shading the bubble with a dark pencil or pen. It is important for the shading to be really dark as only then the OMR software will be able to read the mark and evaluate it. When it comes to the use of pen on an OMR sheet, you can use either black or blue colored pen. Moreover, it is best to use a ball-point pen as it does not leak. However, many have doubts on the use of ink or gel pen on the OMR sheet. Let us find out the answer.