Papers in general and inkjet Photo Papers in particular are normally
measured in GSM which is Grammes per Square Metre. This may confuse some
people as most papers are pretty light and the real difference becomes
clear only by sensing the thickness and/or the stiffness of the paper.

Inkjet Instant dry photo paper or as its called in the professional jargon,
'cast coated', is coated on a cheaper base paper which normally is less
condensed, that cause the paper to feel thicker and stiffer.

The more professional inkjet photo paper is the micro-porous coated papers
or the nano-porous coated one. These coatings are normally done on a base
material which contains denser paper and thin layers of polypropylene on
both sides. This provides the paper with better stability, flexibility and
printer feedability. The paper has a thinner feel to it though still
heavier than a regular instant dry photo paper in terms of Grammes per
Square Metre.

Please bear in mind when buying photo paper that thicker doesn’t always
count for better...