[simonlfcgreen (OP)]

I need to know of a Liquid that would expand allot when it hits air. I would need to be able to colour it and it would still need to be wet so it could colour what it hit's. Please help im so stuck it could be a foam or anything that could fit in a very small capsule. But it would need to expand allot when released from it capsule. Thanks in advance.   

[Jolly- Joliver]

It sounds like you want to compress a paint and then fire it at something.

Having an amount in a capsule, you could use compressed air to spray on it's release from the capsule to increase the area it would cover.

Ways to compress materials, aerosol paint would probably be best.