Panel preparation before applying ground, fluid underpainting with extended transparency, and oiling out between layers to restore color depth.

For panel prep, 3-in-1 creates moisture barriers that prevent warping over time. The chemical bond between this medium and Gamblin Oil Ground surpasses PVA sizing for panel substrates, establishing stable foundations for direct oil work. During underpainting stages, mix as much or little as needed with your colors, particularly iron oxide pigments like Raw Umber, to create transparent tonal washes that dry within 24-48 hours under normal conditions. The medium extends flow without adding high gloss, settling instead into subtle satin finishes that won't interfere with subsequent layers.

When dry passages lose saturation, brush on 3-in-1 and wipe excess away to revive color intensity before continuing work or applying final varnish. This oiling-out technique eliminates patchy surfaces that distract from finished paintings. Compatible with Gamblin's entire medium range and other brands, giving you flexibility across techniques and materials.