Acrylic Flow Release
GOLDEN Acrylic Flow Release is an additive used to reduce surface tension of the water in the acrylic emulsion, therefore increasing the slickness and flow of the paint. It is effective for achieving rich stains on a porous surface. Health Labeled (HL) Product. Not for use by children.
I haven’t used it Ross but Goldens does produce possibly the finest acrylic paints money can buy.
Give it a try and let us know if it retards the drying time to your liking.
Read the label, carefully this time. Taking it back to the store. It might work, but has less application to modeling, I think, than artistic painting. And the health hazard section is rather, um, ungood…[yuck]