The opaqueness of paper comes from the air pockets between the pulp fibers. It is the random reflection of the light that creates the white appearance of paper. To give paper greater transparency, one must reduce the space between the pulp fibers. When creating glassine paper, you must grind the pulp much more thoroughly than regular paper. On top of that, extreme pressure is applied to the paper using a super calender to further reduce space between the fiber, producing a very dense paper with high transparency. Our fountain pen ink tests showed longer than average dry times, but resulted in great color reproduction and no bleed-through.