We take some credit to ourselves for having in the pages of Maga, so long ago as June 1839—promoted an inquiry into the nature of the vehicles used by the old masters. And this we did, knowing that we should incur some odium and contemptuous disapprobation at the hands of artists, too many of whom were jealous of any supposed superiority in their great predecessors, and were generally satisfied with the meguilp, (mastic varnish, beat up with drying oil,) which had, nevertheless, been proved so deceitful from the first days of its adoption. The readiness with which it was made, the facility of working which it offered, and its immediate brilliancy, were temptations too great to be resisted. The too common use of this vehicle, we confess, led us too far in a contrary direction—to set ourselves against all varnishes whatever; and we laid, perhaps, too much stress upon the authority of Tingry, who speaks strongly against the admixture[12] of varnishes with oil; and, with this bias, we reviewed, in Maga, M. Merimée's work, in which, certainly with mistranslations of the Latin of Theophilus, as well as of Italian quotations, he insisted upon the use principally of copal, though without any distrust of mastic.
The difference between the texture of old paint, that is of the good age, both Italian and Flemish, and that which modern practice had exhibited, was too manifest to be overlooked; and we never could bring ourselves to believe that the meguilp in use, by itself, ever had or ever would produce that solid brilliancy or substantial transparency which was and is the great charm in the genuine works of the good old time of the art. And we believe still that all experience is against it, and that the era of its adoption is marked in the history of art by the visible deterioration in the quality of the painted surfaces. Bad as we conceive the use of mastic always to have been, it was not, until comparatively modern times, employed in the most injurious manner. The Flemish and Italian recipes incorporated it with the oil, together, generally, with other substances, by heat, and not, according to the subsequent modern practice, merely dissolved in turpentine and added to the oil. Of all varnishes mastic is the softest, most liable to decomposition, most readily affected by atmospheric changes, having no protection or medium of incorporation, being merely liquified with turpentine, which, evaporating, leaves the mastic to the injuries of air and moisture. Oil varnishes are, however, of another character, and we are converted to their use by historic evidence, and authorities which cannot be doubted. We do not assert that the exact recipes and formulæ, for the compositions of the true oleo-resinous vehicles are not now in possession of the public. We are inclined to think they are; but, as we are promised by Mr Eastlake another volume, chiefly upon the Italian practice, which, too, we presume to think was the best, we in some degree force ourselves to suspend our judgment, resting our hope for what is to come upon the undeniable value of what has been already given us.
When we formerly treated of this subject, we mentioned the great reliance we placed upon the results of the accurate research and experiments of a friend, P. Rainier, Esq., M.D. of the Albany. It is greatly to be regretted that, at his death, his papers were not properly collected and arranged for use; they are, it is to be feared, lost. We well remember his assertion, that the paint of the old masters invariably vitrified by fire. In proof, he scraped off some paint from an old picture, (it was in the shadow part of back-ground, and not very thick, and where there was not, apparently, any white-lead). He laid it on some platina, and subjected it to the heat of the blow-pipe. The oil first exploded, and the paint was vitrified. Hence, originated the borax medium—remarkable property of which was its capability of being used with water as a diluent or with oil,—thus being a kind of union of the earlier temperas and the oil medium. This borax-glass vehicle was certainly a discovery, or rediscovery, as he was inclined to think it, of our highly valued friend, P. Rainier. We say re-discovery, remembering his playful assumption of a motto, "Veterem revocavit artem." He was probably led to this use of a glass composed of borax, by the vitrification of the pigments; and we still suspect that, in some of the old Italian recipes, glass, with borax as an ingredient, will be found. "A peculiar kind of Venetian glass," says Mr Eastlake, "used, when pulverised, as a dryer, contained a considerable portion of lead; and if it acted chemically, may have derived its siccative quality from that ingredient." The question here naturally suggests itself, Why was a peculiar glass used for this purpose, when it was perfectly well known that lead of itself would have been sufficient? Again, in page 358, from the Mayerne MS., as quoting the authority of Mytens; "This oil (mancop) does not dry of itself easily, but it is usually ground with Venetian glass, and thus to the sun in a glass bottle. This should be shaken every four days for three or four weeks: it should then be carefully decanted for use, leaving the sediment with the glass." It is a question if the glass was here solely used to facilitate the sediment.
Vitrification would not depend upon the introduction of glass only,—calcined bones, which, it is now known, were much used in vehicles, will produce the same result. In a note, page 345, Mr Eastlake says that he requested Mr Marris Dimsdale to analyse a fragment of a picture by Cariani of Bergamo, (a contemporary and scholar, or imitator of Giorgione;)—the result being, that "one portion ran fairly into a vitrified state. Hypothetically," adds Mr Dimsdale, "I should say it had burned bones in it." And again, "Every colour mixed with phosphate of lime, (calcined bones,) vitrifies when exposed to strong heat. As Venetian pigments vitrify, might not phosphate of lime have been used as a dryer?"
We cannot but suspect any medium under which the pigments will not vitrify. The publication of Mr Eastlake's most important and valuable volume, rather strengthens our reliance upon the various communications made to us by Mr Rainier. For instance, many years ago, we used, at his recommendation, sandarach, dissolved in spike oil, and then mixed with the oil heated. It may not be amiss here, as sandarach is now so strongly recommended, and shown at least to have formed a part of one of the precious vehicles, to state the result of its use some twenty years ago. A picture we then painted with it, is still without a crack, extremely hard, and though by no means well painted, is good in texture, and resembles in the quality of the pigments very much that of the old schools. Though for some years shut up in a portfolio, the colours do not appear to have undergone any change.
Although it will not probably be found that borax was used in the good recipes by name, it may have been in the Venetian glass—at all events, though we are now rather in search of what was in use, than what may be useful and good in itself, as it were de novo, it may be worth while to remember the double facility it offers of use with oil or water, both or either; and it may be added that the experience of some years shows nothing against it and much in its favour. We have thought it to be a preservative of colours. In our review of M. Merimée, we threw out a conjecture that it might have been the Gummi Fornis in the recipe of Theophilus—and which M. Merimée believed to be copal. But we are quite convinced of our error by the arguments—we might say proofs—adduced by Mrs Merrifield, contained in a note, in her admirable and most useful volume, "Cennino Cennini." That it was sandarach there can be no doubt; and we were in consequence induced to try the making the vehicle according to the recipe of Theophilus, and perfectly succeeded. It has a pleasant lustre, not that somewhat disagreeable shine which is often visible in pictures painted with copal. For the quality of sandarach Mrs Merrifield quotes Raffael Borghini, from his "Reposo"—"If you would have your varnish very brilliant, use much sandarach."
Mr Eastlake has shown that Mrs Merrifield was not quite so fortunate in her remark against M. Merimée's conjecture that the "Gummi Fornis" was copal. "As that is brought from America, it could not possibly have been known to Theophilus, who lived between three and four hundred years previous to the discovery of that country." The name copal, as that of Brazil, is not indigenous to America. Both that gum and dye were African, and transferred to the similar productions of the New World. It is curious that a distinction made between "vernice," and "vernice liquida" should be the means of ascertaining the gum given in the recipe of Theophilus which M Merimée believed to be copal. Vernice was the name of sandarach, and was in common use in its dry state, as pounce, but when made into a varnish with oil, it was called vernice liquida.
To those who delight in etymologies, it will afford amusement to learn that the word varnish is with much reason conjectured to be derived from the name of a daughter of one of the Ptolemies, celebrated for her amber-coloured hair,—the heroine of the poem of Callimachus of which we have only the translation by Catullus, the "Coma Berenices." Eustathius, the commentator on Homer of the twelfth century, states that amber (ἢλεκτρον) in his day was called βερονίκη. Salmasius spells it βερενικι. "Even during the classic ages of Greece β represented φ in certain dialects." Veronica, in the Lucca M.S., (eighth century,) more than once occurs among the ingredients of varnishes. "And it is remarkable," adds Mr Eastlake, "that in the copies of the same recipes in the Mappæ Clavicula (twelfth century) the word is spelt in the genitive—Verenicis and Vernicis," and thus we come by very legitimate derivation to the English word varnish. Sandarach, however, becoming in process of time the common substitute for amber, took the name: and to distinguish this oleo-resinous varnish from that of the real amber, the latter is called "Vernice liquida gentile." The "Mappæ Clavicula," spoken of above, is a very curious publication, in the last No. of the Archæologia, vol. xxxii. part 1, of a MS. treatise on the preparation of pigments during the middle ages. Speaking of the vernice liquida, Mr Eastlake says:—
"The amber varnish had been adopted in its stead by the early Flemish painters, and though often represented by[13] copal, had never been entirely laid aside; it had even returned to the north from Italy in the hands of Gentileschi. Rembrandt, from motives of economy, may have employed the scarcely less durable common "vernix" or sandarac oil varnish; and for certain effects may have reckoned on its tint. Either this, or the rapidly drying Venice amber before described, was in all probability used by him freely."
Mr Eastlake thinks that the darkness of the vehicle had been allowed to increase (and the darker the thicker it would be) with the darkness of the colour employed. That this was the case, we might conjecture, not only from the works of Rembrandt, but we think it may be so seen in some of the back-grounds of Correggio. "The influence of the colour of the vehicle on the quantity and depth of shadow is indeed plainly to be traced in the general style of oil painting, as compared with tempera and other methods." In a note on this passage we are told that "Sandrart relates, it is to be hoped on no good authority, that Rubens induced Jordaens to paint some works in tempera for tapestries, in the hope that his rival, by being accustomed to the light style of colouring suitable to tempera, might lose his characteristic force in oil. The biographer even adds that the scheme answered."