Jackson's : Fast Drying Oil Painting Medium : Gloss

Jackson's fast drying medium for oil and alkyd colours improves flow and transparency for glazes, detail work, and smooth brushwork. Good resistance to yellowing. It is advised to store Jackson's Oil Medium at a stable temperature. Storage in an overly hot or cold environment will affect the consistency of the product. Colour and viscosity may vary in storage. Shake container before use.

Jackson's Fast Drying Oil Paint Medium should be quite a fluid medium. If you find it getting too thick, here is a good way to keep it workable:

Maintenance of Alkyd Mediums
Like all alkyd-based mediums, the introduction of air space in the bottle allows for solvent evaporation and drying - even with the lid closed. To compensate, add a little solvent of your choice to the bottle immediately after use and shake it well to maintain the desired thickness of the medium. We tested a variety of types of solvent and they all worked.

Rescuing Thickened Alkyd Medium
If your painting medium has thickened but is still fluid, add in a small amount of solvent and shake thoroughly. Continue adding more solvent and shaking until the medium is close to its original consistency. If a fluid alkyd painting medium has thickened to a gelled consistency, it will no longer help to add solvent - unfortunately, it cannot be rescued.