Determining the impact of installing multiple types of air barriers and vapor retarders in the wrong place within wall and roof assemblies, and (buildingscience.com)
I use a q tip to remove areas of wet paint in the lighter areas, and darken the shadow areas by reducing the amount of fluid retarder mixed with the burnt umber: with an under painting you begin with the lighter shades and gradually work your way up to the darkest darks. (arttutor.com)
Then use that mix in the same ratio as the gel retarder alone (20 % medium - 980 % paint). (arttutor.com)