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Portuguese Balsam Medium:
1 Part Sun-thickened linseed oil
1 Part Strasbourg turpentine (preferred) or venice turpentine
1 Part pure gum spirits of turpentine
1% Oil of Spike Lavender (optional)
3% Lead oxide drier (optional)
Stir the oil and Strasbourg turpentine together until completely mixed. Add gum turpentine to the desired consistency. The oil of spike is probably there to make it smell better. Lastly mix in the drier.
Balsam Glazing Medium:
1 Part Linseed Oil
1 Part Walnut Oil
1 Part Venice Turpentine
2 Parts Oil Of Spike (can be substituted with gum turpentine)
Add a small amount to paint to improve gloss, transparency and leveling.
Balsam Glazing Medium #2:
4 Parts Turpentine or Oil of Spike
1 Part Sun-thickened Oil
3/4 Part Canada Balsam
Leaner version of above. Add a small amount to improve flow, gloss, transparency and leveling
Black Oil:
I or 2 Parts Litharge
20 Parts Linseed or Walnut Oil
Grind the litharge with some of the oil before adding it with the rest of the oil. Place the receptacle containing the mixture over a low fire and stir constantly with a spatula during the cooking.
Between 180 and 200 degrees centigrade, the oil begins to smoke and to become brownish in color. This is the sign of the beginning of its combination with the lead. The litharge has a tendency to agglutinate at about I50 degrees, and the spatula will stick in it at the bottom of the vessel. Towards 2I0 degrees, however, this deposit softens and it will finally mix with the oil at about 230 degrees. Towards 250 degrees, the oil takes on the brown and transparent color of coffee and loses the muddy look it had earlier in the process.
If there is no means of gauging the heat, as with a thermometer, it is important to see that the oil smokes only very slightly. Too long and too hot a cooking (as high as 280 degrees) will lend to a sort of rubberiness in the oil and the product will be unfit for use in painting.
It is difficult to give precise instructions as to the length of time this oil should be cooked. The masters always spoke of a "low fire," whatever they meant by that, and they spoke of also of two hours of cooking. When the oil has become a dark brown and the foam which partly covers it has taken on a the golden tone, the lead should be entirely combined with the oil and the operation might be considered as finished. But with this is a matter of individual taste and another artist might have a preference for an oil that has been cooked for a longer or shorter time. Over a low fire the cooking might be allowed to last for from two to three hours to obtain a thicker and more brilliant product. After the cooking is finished, the temperature of the oil must come down to 75 degrees centigrade before it can be poured into a bottle.
Let it sit for a week or more until all the lead has settled to the bottom and then carefully decant into a bottle. Marbles can be added to keep the level at the top of the bottle.
Fast Dry Glazing Medium:
1 Part Sun-thicked Linseed Oil
1/2 Part Black Oil
1 Part Venice Turpentine
1- 2 Parts Turpentine (use more or less to adjust leanness or fatness)
Add a small amount to paint to shorten drying time and improve gloss, transparency and leveling.
Italian Drying Medium:
From Secret Formulas and Techniques of the Masters, by Jacques Maroger
(all measurements are given by weight):
10 Parts Raw Linseed Oil
1 Part Litharge
1 Part Beeswax
Grind the litharge with some of the oil before adding it with the rest of the oil. The mixture is then simply heated to 250° C. It is done when it turns dark black brown. It thickens into a paste when cool
Solvent Free Medium:
2 Parts Black Oil (substitute stand oil for longer dry times)
1 Part Venice Turpentine
Improves flow, speeds drying time, reduces brush stroke, adds a glossy enamel like finish.
Sun-thickened Oil:
1 Part Linseed or Walnut oil
1/20 Part Litharge (optional)
If using litharge it is best to grind it with a little oil first. Place the oil and litharge in shallow dish made from glass or lead (lead roof flashing can be used to form a pan). Place in a southern facing window so it gets direct sunlight. Cover with a sheet of glass and stir well every day or so to keep a skin from forming. When it reaches the desired thickness it is done. It takes about 3 weeks to several months depending on heat, amount of sun, type of oil and degree of thickness desired. Decant the oil into glass container. If litharge was used, allow to rest a week or so to make sure all the lead has settled and re-decant.
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Traditional Chalk Gesso:
3 parts of glue size (by volume)
1 part chalk
1 part pigment (usually lead white or titanium white, but other pigments can be used for for colored grounds.)
Chalk Grounds: Directions
Measure out the glue size solution into a metal container. Add the dry ingredients. Stir well but avoid getting air-bubbles. Place container in a double-boiler or enclosed hot plate. Apply warm mixture with a broad brush. Allow layer to dry to the touch and recoat.
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Marble dust:Add marble dust or chalk to oil paints and gessoes to make a thick impasto paste, extend colors or add texture, tooth and body.
