You really need to get Robert Bruce's book, "Practical Psychic Self Defense." I've read it, and although I am more interested in Robert's abduction experiences, his writings and ideas are fascinating. Bruce does something I have never seen before, he takes a scientist view of things and deliberately tests them.
Inks and their varieties are some of the things he has tested and it is listed in his book on page 206:
The Effect of Ink and Color: I have experimented with different types of inks, dyes, and colors, but blue ballpoint ink seems to work best. Black and violet also work fairly well, but red ink seems less effective. It's possible the ink itself is causing these strange effects, as the type of ink used is important. I have tried dye pens and applying blotches of ink over skin blemishes with poor results. However, it seems more likely that the combination of ink, color, and geometric design all contribute to the result.
Inks and their varieties are some of the things he has tested and it is listed in his book on page 206:
The Effect of Ink and Color: I have experimented with different types of inks, dyes, and colors, but blue ballpoint ink seems to work best. Black and violet also work fairly well, but red ink seems less effective. It's possible the ink itself is causing these strange effects, as the type of ink used is important. I have tried dye pens and applying blotches of ink over skin blemishes with poor results. However, it seems more likely that the combination of ink, color, and geometric design all contribute to the result.