Matisse Acrylic Medium MM24 Iridescent MediumMix with Matisse Colours to achieve lively iridescent effects. (Size: 10L, 250ml, 1L) This medium is formulated to be mixed with the Matisse Structure or Flow Formula acrylic paints to add an iridescence (metallic sheen) to them. MM24 Iridescent Medium can be mixed in any proportion with Matisse Colours. This medium is based on pure iridescent pigment and contains no fillers or titanium dioxide; therefore the resultant mixes of iridescent colours are