I recently placed an order with Hattons which included Humbrol acrylic paints, in pots not aerosols.
I had a call from Hattons to tell me the order would be despatched by yokel, not royal mail as requested, due to this.
I then queried this with royal mail who confirmed that water based paints etc, ie acrylics, can be sent by post.
when I went on chat to Hattons and advised them I was told their contract with royal mail stopped them from sending any liquids by post.
just thought it might be of interest to some of you.
cheers
alan