The OMR sheets have to be filled either by pen or pencil. The tool used for filling these sheets would differ from exam to exam as this is decided by the examination body or committee. The instructions section of the OMR sheet states whether the candidate can make use of pen or pencil. Hence, always read the instructions before you start answering the paper. Here are some of the instructions that you have to follow while filling the OMR bubbles with pencil as well as pen.
OMR sheets based on the new OMR technology prefer the use of pen over pencil. However, in some cases if the examination body is using the old OMR sheets, the students or candidates would be asked to use a pencil.
However, you cannot use any pencil available in the market for this purpose. You should either use an HB or 2B pencil, as you have to make dark marks on the bubbles for the software to read and recognize them.
Always buy two or three types of pencils before the exam. Check the pencil for darkness and use the pencil which is the darkest for filling the OMR bubbles.
Most OMR based exams today require the students to fill the OMR sheets with a pen. You can either use a black or blue ball point pen for this. If you are asked to use a specific pen (blue or black) by the exam body, it is best to stick to that specific pen.
Use a ball point pen for filling OMR bubbles.
Restrict the use gel pen to fill your sheets, unless permitted
Although gel pen is acceptable in some cases, ink pen, marker pen and sketch pen should never be used for filling OMR sheets. The ink of these pens is likely to spill or bloat, damaging the OMR sheet, making it unreadable for the OMR software.
Whatever type of tool you use for filling the OMR sheets, you should make sure that you fill the bubbles completely and not under-fill or overfill them. Moreover, although it is necessary to darken the bubbles, do not darken the circles repeatedly, especially if using pen, as this can cause blotting on the sheet.