Winsor & Newton Artists' Watercolor (BlickVideos)

The preservatives in pan colours, if they exist, don't really help in preventing pans from turning moldy.

There's no better way to prevent mold than to dry your pans thoroughly. Same applies to brushes. Dry them before storing them away.

You can find all sorts of Winsor & Newton Watercolour products on Amazon (US | UK | DE | FR)