Carthame Oil (Purified Safflower Oil) - Poppy oil has been used in paint formulations for centuries. A relatively new alternative has been Safflower oil. Yes this is a non-acid vegetable oil. It is a useful substitute for artists who can't get Poppy oil. It tends to be slightly more yellow than poppy. You can also use this oil to make colors more fluid and brilliant while painting without altering the shade while drying.
Clarified Linseed Oil - Linseed Oil is extracted from the seeds of the flax plant, which are pressed and lighty toasted. Linseed Oil creates a very good paint film which is hard, resistant and flexible. Linseed Oil also reacts well with additives and is by far the easiest oil to make oil colors with when combined with pigment. The disadvantage is that it will slightly yellow. One strange phenomenon of Linseed Oil is that in the dark the oil darkens quite a bit but when exposed to sunlight it will lighten.
Clarified Poppy Seed Oil - This is an oil made from the seeds of the black poppy. When mixed into color it produces a hard film that is resistant and flexible, although not as quick drying as Linseed Oil. However, it has very little color and therefore has very little tendency to yellow with age. Some pigments are very fragile and Poppy Oil is non acidic so it doesn't attack the chemical nature of these pigments. For these reasons it is mixed with Linseed Oil in a guarded formulation which is generally said to be 50/50% ratio in the creation of Charvin Oil Colors. Poppy oil is slower drying than Linseed Oil so care should be taken not to use only Poppy Oil as the drying rate will be very slow.
Siccative of Courtai - This drying agent should never exceed in volume greater than 5% as compared to what you are mixing it into.
Walnut Oil - This is the palest of the oils used in paint manufacturing. It too has a similar effect on slowing the drying rate as compared to using linseed. It is made from nuts and anyone allergic to nuts should avoid exposure to this product. For this reason it is not suggested for classroom painting.