There is no strict rule that says we can't write with red pens, but there are some practical reasons why red pens are generally not the preferred choice for writing in certain situations:
Readability: Red ink can be harder to read, especially when used for long passages of text. The contrast between red ink and the white paper is not as high as with standard black or blue ink, making it more challenging for some people to decipher the content.
Professionalism: Red ink is often associated with marking errors or corrections. In educational settings, teachers commonly use red pens to grade papers and indicate mistakes. Using red ink in other contexts might inadvertently give the impression of marking or criticizing the content, which may not be appropriate for general writing.
Formal Documents: In formal or official documents, it is often preferred to use black or blue ink for the sake of clarity and legibility. Legal documents, contracts, and important paperwork usually require ink colors that can be easily scanned, photocopied, or stored without any loss of information.
Cultural Connotations: In some cultures, red ink is traditionally used for writing negative comments or expressing disapproval. As a result, using red ink might carry negative connotations in certain social contexts.
Copying and Scanning: Red ink can sometimes cause issues when photocopying or scanning documents. For example, some copiers or scanners may not reproduce red ink as accurately, resulting in a faint or distorted output.
Despite these considerations, there are instances where red pens can still be used effectively. For example, correcting papers or providing feedback on assignments, or simply adding emphasis to certain points in a text can be suitable uses for red pens. Ultimately, the choice of pen color depends on the context and personal preferences, as long as it does not compromise readability and clarity.