Linseed Oil is an extract of the seeds of flax. Poppy Oil is extracted from poppy seeds. Both are used for thinning oil colors. As these oils are the base medium of oil colors, their use as a thinner imparts a natural luster to the painting.

However, Linseed Oil is a vegetable based oil and a slight residue of solid oil is left when dry which sometimes causes a yellowing problem with the passage of time. Poppy Oil does not have this disadvantage and most discerning artists use Poppy Oil for this reason.

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