Golden Retarder (Acrylic Medium)

Golden Retarder "Golden brand retarder is an additive for acrylics, used to increase drying time, enabling artists to work for longer periods on their projects. It also reduces hardening of colours on a palette, and is useful for work-on-damp techniques. Available in 120-ml (4 oz) and 250-ml (8 oz) sizes. Practical information: Delicately mix no more than 15% of retardant with acrylics." I think the Retarder is to be used for regular acrylics so that they work better with the OPEN ones? IDK 😅 Please see photos. Sold as is. Comes from a cat-friendly home.