How do I make a sporeprint?

It's simple to make a spore print from a mushroom.

• Remove the stem by carefully cutting it off where it meets the cap.
• Put the cap on a clean piece of paper (fresh typing paper for instance), gills facing down.
• Cover the paper and cap with a glass, a jar or tub of some sort - to maintain the humidity around the cap.
• Leave it for a few hours (typically overnight) and then remove the jar and cap.
• Cover the print with a clean paper napkin and let it dry until the paper is not moist anymore
  

Over the hours, mature spores (and only mature spores) will have been released from the gills and fallen onto the paper. What you see in a spore print,is a mass of hundreds of thousands or millions of spores. In this quantity the color is easy to see. The commonest spore colours are white and various shades of brown. If the spores are white, you obviously won't see them very well on white paper. It might be a good idea to place the cap halfway on white and half on dark paper.

Note that the colour of the gills need not be the same as the colour of the spores.

If your spore print is very weak (or not there) put the cap and tub back down and leave it for longer - even overnight. Some species take a long time to build up a good spore deposit.

It's also possible that the cap had already started to dry out when you collected it. Put a couple of drops of water on the cap, or a damp cotton ball next to the cap before putting the tub over. It's hard to get spore prints from mushrooms with small, thin caps. They dry out very quickly.