Yes, respondents can use most pen colors to fill out paper surveys. PaperSurvey's recognition engine is designed to detect marks regardless of ink color.
Recommended colors
Black and blue ink produce the best results. These colors provide strong contrast against white paper, making marks easy to detect. Scans are processed in grayscale, so what matters is how dark a mark appears, not its color.
Colors to avoid
Light colors such as yellow or light green may not be detected reliably, especially at lower scan resolutions. If respondents have a choice, darker colors are always better.
Red ink can work but may produce weaker contrast depending on your scanner settings, particularly if scanning in grayscale. If you expect respondents to use red ink, consider scanning in color mode.
Best results
For the best recognition accuracy, we recommend using a black or blue pen.
Faint or thin marks
Whatever pen is used, instruct participants to make solid, dark marks and to check, cross, or fill in the whole checkbox area. Thin lines or light checkmarks may not be visible to the scanner.