Influence of Grounds on Paint Preservation

[George O'Hanlon]

It is well known that oil paint darkens and becomes increasingly translucent as it ages. These changes cause visible disfigurement of paintings and, although the phenomenon has been extensively studied, the causes are not definitely known at present.

One way to think of this change is to imagine your painting like a stack of colored glass that with time becomes increasingly darker and more translucent.

This being the case, underlying layers of paint will become increasingly visible, and if they are darker than those of the upper layers, they also acerbate the darkening effect.

These changes can be mitigated by painting over a white ground, insuring that the ground is sufficiently thick and opaque and by building the painting from lighter to darker layers of paint. If it is not possible to build the layers from light to dark, than it is important to apply sufficiently thick and opaque layers, preferably with lead white.

[John Kennedy]

If I understand this correctly, can't you use a small amount of smalt as well, and get a simular effect with the more opaque layers? Seems I read about that in my Eastlake book. Doesn't it have something to do with the stability and drying effect on the paint? Just curious!

John

[bjr001]

A picture is worth a thousand words.


What percentage of oil paintings have exhibited this phenomenon of the top oil paint layer becoming transparent over time?

Is this phenomenon more prevalent in works from one particular century?

Is this phenomenon more prevalent in works from one particular “school” of painting?

Is this phenomenon more prevalent in works done in one type of painting technique?

Is this phenomenon more prevalent in areas of an art work done in one particular hue?

Is this phenomenon more prevalent on works done on gesso over panel verses oil on linen?

Is this phenomenon more prevalent in works done using linseed oil, walnut oil or poppy oil as either the medium or binding oil of the paints?

Which old masters works did not suffer from this phenomenon, if any?

Is one particular old master works more prone to this phenomenon?

When was this phenomenon first observed and written about?

Is there a time frame in which this phenomenon begins and does it stabilize after a while or continue to become transparent?

Have any “X-Ray”, electronic microscope and other such types of studies been done on these art works?

[George O'Hanlon]

Originally posted by John Kennedy:
If I understand this correctly, can't you use a small amount of smalt as well, and get a similar effect with the more opaque layers?

I am not sure how this relates to building layers of painting and the increasing translucency and darkening of oil paint films.

[George O'Hanlon]

Originally posted by bjr001:
What percentage of oil paintings have exhibited this phenomenon of the top oil paint layer becoming transparent over time?

The phenomenon of increasing translucency of aging oil paint films has been observed in paintings since at least the 19th century (see note 1), but most likely it was observed much earlier since literary sources from the early Renaissance warn against the application of thin grounds on panels.

A.P. Laurie wrote about it since the first part of the 20th century, ascribing the phenomenon to the increasing refractive index of aging oil paint films. However, it was also found to be acerbated by the dissolution of pigments reactive to fatty acids in oil paint, such as lead white and zinc white, and the subsequent formation of mineralized metallic soaps (see note 2).

Early oil paintings from the 15th century, such as those by the van Eyck brothers, seemed to have overcome this problem due to their careful preparation of the ground of the painting panel and their painting technique. However, as artists in subsequent centuries from the 16th century and later became more negligent in their preparation of the ground and painting technique, or used the grain pattern of wood panels as a visual device in their paintings, such as in the landscape paintings of Jan Josephszoon van Goyen (13 January 1596 – 27 April 1656), this phenomenon is more often observed. Many of van Goyen's paintings are now undisplayable because of the visible disfigurement caused by increasing the translucency of the paint layers.

This phenomenon is also observed on canvas paintings by the general darkening of the painting resulting from the color of the canvas striking through the upper paint layers.

Where paintings had properly prepared grounds and opaque underpaintings, this phenomenon is least observed.

Notes
1. In 1839, Henri Fielding refers to Van Goyen's and others use of transparent grounds as being 'the destruction of many fine pictures' stating that '...Van Goyen and others have prepared or filled up the pores of the wood with their transparent vehicle, which also enabled them to shew the grain of the wood through the shades of the subject.'

2. For an interesting discussion on this topic of 17th century paintings, see Annelies van Loon (2008) "The relationship between preservation and technique in the paintings of the Oranjezaal," Color Changes and Chemical Reactivity in Seventeenth-Century Oil Paintings, p. 51–52, 236. See also Petria Noble, Annelies van Loon and Jaap J. Boon, “Selective darkening of ground and paint layers associated with the wood structure in seventeenth-century panel paintings,” in Preparation for Painting: The Artist’s Choices and Its Consequences, Joyce Townsend, et al, Editors, p. 76.

[bjr001]

Why would any artist want to use traditional oil paints? Least of all, lead white.

[George O'Hanlon]

If you attended my lecture entitled "Making It Last" you would have learned that lead white forms the strongest paint films, whereas many modern pigments do not. That there are some issues with lead white comes as no surprise, because all materials degrade with age, even our modern materials.

In any case, the issue described above is with oil and not necessarily with the pigments used by the old masters, although some pigments used by the old masters were less lightfast than those today.

What we learn that there are compromises with all materials. No material will last forever and presents both advantages and disadvantages. Titanium white for example, forms a weak paint film, and does not provide the coordinating points as does lead white that stabilizes the oil matrix, because it is inert to vegetable drying oils.

[George O'Hanlon]

John,

Were you were referring to the passage in Eastlake found on page 427 of volume 1 of Materials for a History of Oil Painting? Eastlake was discussing the "sinking-in" phenomenon in oil paint, where pigment particles subside in the paint film forming a 'thick and more or less yellow skin of oil above delicate blues and greys.' De Mayerne observed that the 'supernatant oil in drying forms a skin, which darkens by [long] exposure to the air. There are some colors, such as smalts, which are not easily miscible with oil, but always subside without combining with it. They easily fade and become darkened.'[See note 1]

This form of darkening is due to an medium rich paint layer and heavy pigment particles, but is different from the phenomenon that I wrote about above.

Notes
1. Sloane MS. 2052, p. 9 verso.

[ 23. June 2011, 07:16: Message edited by: Admin ]

[John Kennedy]

George,

I read so many art material books that I can't remember what I was referring to. This may have been it or else where. I think my point may have been related to something to the effect, that I was assuming that smalt either acted somewhat simular to lead white, possibly properties wise or stability wise in building up layers using opaque colors.

This is what happens when you get my age and have three hundred things going on your plate at the same time. It's not that I'm brain dead, but more like brain over worked and forgetful at times.

Next time I will have to make sure I have my books open to the right page for commenting, so as not to create any confusion. Maybe that is why I put it in a question form out of curiosity, because I couldn't remember what exactly it was that I had read.

It may have been something I read in De Weterings book Rembrandt The Painter at Work in the colors of his palette, dealing with smalt. I would have to look through several books, but don't have the time right now to see what it is that I may have brought up. It wasn't page 427 though in Eastlakes book, as I looked and that wasn't it.

If however, I do run accross it and find it pertonant to the subject above, I will post my results. But, thank you for trying to help jog this old boys memory and the information.

[bjh]

"These changes can be mitigated by painting over a white ground, insuring that the ground is sufficiently thick and opaque and by building the painting from lighter to darker layers of paint. If it is not possible to build the layers from light to dark, than it is important to apply sufficiently thick and opaque layers, preferably with lead white."
I have been enjoying the transparent/translucent paints by NP. How can the lead whites be made more opaque for the first layer? I don't think merely setting the paint on an absorbent paper will make it opaque enough.