Microfibre is the most absorbant fabric for weight, but most people think bamboo is the most absorbant natural fabric, though hemp is a close second
Some people dont like to use microfibre as a sewn in component of nappies cause its a synthetic which some find needs more thorough cleaning than natural fibres. However, some people sew in microfibre with no issue as all. Goodluck
eta - I was also gonna say 2 hours on a newborn is a reasonable time imho