[Richard Bingham]

Originally Posted by Marvin Mattelson

. . .I wouldn't be so quick to dismiss cold pressed linseed oil . . .

I really had no intention of dismissing it. How does one know (for sure) what exactly is entailed in one's materials ? Since CP "flaxseed oil" available as a health-food item turns rancid if unrefrigerated, what processes entail for cold-pressed oil available as art material, which doesn't go bad?

Originally Posted by Marvin Mattelson

. . . I have never experienced any tube of Old Holland or Michael Harding turning rancid . . .

Nor have I. Question: Is it possible the admixture of pigment stuffs is sufficient to prevent rancidity? Also, it's easy enough to tell when CP goes bad in the bottle, but would rancid paint be readily detectable?

Originally Posted by Marvin Mattelson

Cold pressed linseed oil makes the most flexible and durable paint film and was used by the old masters. . . . Cold pressed is also the most stable with regards to color . . .

Absolutely. The "old masters" used CP because it was the only extraction process available at the time. Developments in production methods of linseed oil after industrialization have resulted in a range of oils of differing qualities and characteristics.

Originally Posted by Marvin Mattelson

Alkali refined linseed oil was developed in the 19th Century. In many cases paintings painted in the last 150 years show much more evidence of deterioration, discoloration, darkening and cracking . . . Modern doesn't necessarily mean better.

Again, I heartily agree. Whether these failures have to do strictly with the advent of alkalai refined linseed oil, or in part, with questionable pigment stuffs and equally questionable studio methods is likely unprovable. The major difference was the shift from preparation of paints and materials in individual studios to the industrialized production of paint materials. As we use materials made by others, we remain in the same "materials limbo" as our 19th century predecessors. So far as it's difficult or impossible to learn the exact nature of the materials we use, it's quite impractical if not impossible to re-create 17th century materials and techniques in our own studios.

Originally Posted by Marvin Mattelson

. . . In my opinion using Maroger, alkyd resins, natural resins or varnishes in . . . painting mediums is highly questionable.

And eternally debatable, controversial, and decisively unprovable. The collapse of the medieval guild system ended generational transmission of the knowledge of materials and methods from masters to apprentices. This means there really are "lost secrets of the old masters". And that's the most compelling reason for modern painters to learn the all they can about materials and their wherefore. Coupled with extensive practical experience, each of us must make our own "best guess" for using materials and methods that provide the best means for efficiently expressing our art, as well as reasonable assurances of durability.

Originally Posted by Marvin Mattelson

. . . All manufacturers have numbers, explanations and statistics which seemingly prove the superiority of their modern ingredients.

The "big lie" is that safflower oil and linseed oil are chemically the same . I'm not a chemist; I don't know. I do know there is a world of difference in their using characteristics. With the sea-change in the paint/varnish industry the last 25 years, where synthetic materials have almost entirely supplanted natural oils and resins, the supply of linseed oil has become undependable and the price very high. Safflower oil, however, is produced abundantly and cheaply to supply massive demand in food industries. It's well to remember that art materials represent a miniscule portion of the pigments and vehicles manufactured to supply industry. Convenience and profitability dictate the quality and types of materials that filter down to this small niche. Consequently, better materials (and the full disclosure of contents, etc.) are more likely to be forthcoming from small concerns where artists produce materials for other artists.

Originally Posted by Marvin Mattelson

Personally, the fact that a particular refined linseed oil is used in the finest printing inks is far from a valid reason to trust it's viability as a superior vehicle. The printing industry, in my experience, is not too concerned with longevity.

That sounds reasonable, except that the requirements for compounding printing inks demand similar qualities from linseed oil as does the making of good oil paint. I have a different experience with the printing industry; "high end" printing and the production of color specialty printing is very concerned with longevity, and the industry supports extensive and rigorous materials standards; we'd be so lucky to have similar research and standards in place for art materials! Finally, simply to say "printers ink" is an over-simplification. Obviously, the same quality and care in material is not going to go into printing the daily newspaper, or common job-printing items. The "workhorse" ink type is rubber based . . . linseed oil inks are in a quality tier that corresponds to the care you use in selecting your oil paint.