Blackwood's Edinburgh Magazine, Volume 57, No. 356, June, 1845

Although we would here willingly end the discussion as to the discovery, we feel ourselves irresistibly led by the importance of the subject to make a few observations, and perhaps throw out a few hints, presuming that they are nothing more than hints, which suggest themselves upon paying some little attention to the actual words of Vasari; and this we do solely with regard to vehicles. Why, we should ask, did Van Eyck dry his picture in the sun, and which seems to have been the practice? As far as we know the nature of gums, there is no difficulty in their drying, without the necessity of resorting to any injurious practice. Were these gums in any degree mixed with undrying substances? Why does Vasari say "che secca non teme acqua"—"which, dry, does not fear water?" Why does he mention water at all? for, supposing that he knew of oil-painting without these "altre sue misture," there would appear to be no occasion that he should mention, as a distinct property of this new vehicle, that which was common with that and the older practice. Here a suggestion seems to let in a glimmer of light. Did he convert these oils into a soap, which, when dry, was no longer soluble in water? Will this be the case with saponaceous oils? Unquestionably. One of the objections made by Lanzi to the changes from the good old method was, as when he speaks of Maria Crespi, that the paint was common and oily, and elsewhere complains of "oily appearances." The "colori oleosi" is perfectly descriptive, too, of our modern paint, notwithstanding that our painters try in vain to disguise the "oily" appearance by the admixture of varnishes, and that not a new practice, as we find from Cennino, but one rejected. But can oil be deprived of this appearance? We presume it was deprived of this quality by that process by which, when dry, it did not "fear water"—"secca non teme acqua." Oils are rendered saponaceous by alkalis. We mentioned in former papers experiments of our scientific friend, P. Rainier, M.D. of the Albany, and his use of borax with the oil. The borax he vitrified; and it was because the paint mixed with this oil and borax vitrified also, after the manner of the paint of the old masters, he so used it; but nothing occurred to him about water. We suggested that if this, his medium, resembled the old, it was probably miscible with water, as water would seem to have been introduced into the Venetian practice. Upon this we tried it, and found we could at pleasure dip the brush in this medium, or in water, and then into the paint, and work with great facility, the greater use of the water giving that crumbly appearance so often perceptible in the Venetian school; and this effect we found might be increased or omitted at pleasure. And this medium, made by mixing water with the oil through the agency of borax, when dry might be washed even with warm water with perfect impunity. When dry it did not fear water; though a saponaceous medium, it was not again soluble in water. What does Vasari mean by "che accende i colori"—"which heightens the colours?" Borax is an alkali. Alkalis are known to heighten colours, "e gli fa lucidi;" now, linseed and nut oil alone, particularly the former, takes away the lucid character from paint. Had Vasari been describing the working of this vehicle of P. Rainier, he could not have better described it than in the very words "gli unisce mirabilmente;" for it is astonishing how nicely to the hand, and to the degrees desired, these repugnant liquids unite the colours. It is singular enough that soda, which is a form of borax, is the actual constituent part of some of our most permanent colours—we need but mention ultramarine; and here we are tempted to transcribe a passage from the translator's preface, which exactly falls in with this our view.—"The use made by the early Italian artists of lyes (lisciva) is deserving of our notice and consideration. Cennino does not inform us how this lye was prepared; but it has been ascertained that lyes produced from pouring water on wood-ashes, from solutions of borax, and also of soda in water, were then used. We find from Cennino's book that ultramarine (of which soda is a constituent part) was prepared with it; that it was also used in preparing azzuro della magna, (an ore of cobalt,) and zafferano. It has been likewise ascertained that soda has a preserving influence on red, yellow, and black pigments; and the result of experiments on these colours has been so satisfactory, that a certain quantity of soda—or, to speak more correctly, of soap, which is a compound of soda with fat or oil, (but not drying oil)—is now used in preparing pigments for painting sails for the British navy. It is also used in the manufacture of printing-ink; and we have now Cennino's authority for using it with blue pigments. Sir Humphrey Davy informs us, that the Vestorian or Egyptian azure, the excellence of which is proved by its duration of 1700 years, may be easily imitated by carbonate of soda, opaque flint, and copper filings. The translator has made many experiments on the effect of the alkalis and neutral salts when mixed with colours, and has every reason to be satisfied with the addition of soda, when properly used." We have not ourselves tried sufficiently soda with oil, and have suspected it would not have the effect of rendering the paint hard; but that borax does render the paint very hard we have abundant proof. We have subjected a picture painted with it to the razor to scrape it down, and could with difficulty succeed, though the picture had not been long painted; and we have rolled together masses of paint so mixed, and they have been thought by persons into whose hands we have put them, stone. We have heard artists, who have tried this mixture of borax and oil, declare it had the contrary effect; but, on enquiry, found that they procured the vehicle from colour-makers, who sold them, we have good grounds for believing, a mixture of their own, in which, if borax formed any part, mastic varnish formed a much larger. Among our papers we found one sent us by Dr Rainier; we were not chemists enough to make it intelligible, and for that recipe which we give in a note,6 we are indebted to our friend Mr C. T. Coathupe of Bristol, on whose chemical and general scientific knowledge we have great reliance, and who much confirmed our view, or rather Rainier's, of the advantage of rendering the oils saponaceous by the means of borax. In consequence of our communication with him, Mr Coathupe published in the Art Union one or two very valuable papers in 1842. In speaking of this vehicle we do so the more boldly as it is not our own, nor do we claim the least merit on account of it; it is solely the discovery, or re-discovery, be it which it may, of our ever valued friend Rainier, now no more. Without saying that it is or is not the old one, "che tutti i pittori del mondo aveano lungamente desiderata," we do not hesitate to say that it is a good one, and does obviate those "oily appearances so disagreeable to the eye"; and we are the more confirmed in our belief in its beneficial quality, by the authorities Mr Coathupe and Mr Field, the well-known scientific author of "chromatography;" and we are much gratified to be able to offer an extract from a letter from Mr Field upon the subject:—"I am accordingly ready to admit all the uses of Mr Rainier's medium, and go with him in believing the old painters may have employed it—the Venetians in particular, who were at that time the medium between Europe and India, in the latter of which countries borax had been employed in painting time immemorial." It should here be remarked that Mr Field, in one of his valuable publications, mentions a mixture of lac and oil by means of borax in certain proportions. They do not, however, readily mix, especially in cold weather. The translator does not seem to be aware that borax is the solvent for lac; she mentions "sulphuric or muriatic acid," but water with borax alone will dissolve lac before it boils.7 We would venture to recommend some experiments with lac dissolved in borax to water-colour painters. It is by no means improbable that some of the old Greek paintings are in gum lac; the hardness ascribed to them, and their brilliancy too, and that they rather chip off than crack, seem to answer the properties of lac; and it is curious that lac so dissolved is durable, and not again soluble in water. It may therefore be worth while to try experiments with it, both for solid painting with white lead, as likewise as an addition of power partially used for water-colours. We know not if the ancients had any means of discharging the colour, (though a weak solution, in cases of solid painting, may not be very objectional,) but shell-lac can now be rendered perfectly white.

The reader will be disappointed if he expects to find in "Cennino Cennini" a treatise on art. It is nothing more than a book of receipts—very minute and circumstantial as to most particulars, while here and there is a provoking omission; as, for instance, he speaks of a varnish, but omits to say of what materials composed. However curious much of the matter may be, the modern painter, who has to send to the nearest colour-maker for his tube colours, and French brushes, will think the greater part superfluous, and will smile to be told—"Take the tails of the minèver, (for no other are good,) and these tails must be baked, and not raw." Nor will he trouble himself with Cennino's list of colours, though it would perhaps be better for him if he did enter a little into their chemical properties. Cennino mentions twenty-four pigments; but the best he considers to be but twelve. It is curious that among them are no browns. We have always been of the opinion that the old masters, for the most part, made their browns with blacks and reds and yellows, and gave them depth by glazing over with the same; and we are pretty much of Wilson's mind, who, when told of a new brown, said "I am sorry for it." Very many of our modern pictures are ruined by the violent contrasts of the asphaltum and similar browns with less obtrusive pigments. The very transparency is, in our eyes, an objection. Asphaltum, for instance, besides that it is a changeable and never thoroughly drying pigment, is too transparent for depth. It was a mistake of Gainsborough when he said that with asphaltum he would make a Tartarus; the depth would be but a little way from the surface; depth is not always intensity of darkness, and never of colour. There is a style of flashy painting which entirely depends on these transparent browns; but it is nevertheless not a good style; it is flimsy, and the depth aimed at is missed. The more simple the palette, the better will be the picture. We are taught by the practice as well as words of Titian, who said that "whoever would be a painter, should be well acquainted with three colours, and have a perfect command over them." There are some excellent observations on this subject in the translator's preface, who quotes from Sir Humphrey Davy on colours. "If red and yellow ochres, blacks and whites, were the colours most employed by Protogenes and Apelles, so are they likewise the colours most employed by Raffaelle and Titian in their best style. The St John and Venus in the tribune of the gallery at Florence offer striking examples of pictures, in which all the deeper tints are evidently produced by red and yellow ochres, and carbonaceous substances." Cennino's argument for the use of fine gold and good colours, will be read with more attention by the modern Germans, who have, it is said, for the purposes of their art joined the Catholic Church, than by our English artists, with whom it will but raise a smile, that the artist should be liberal in both, for that if his patron pays him not, our Lady will reward him for it in soul and body. If the practice of poor Cennino was in accordance with this recommendation, he must have been very pious in his resignation, for his reward was a prison in his old age. Cennino acquaints us how to make and prepare pannels, cloth-grounds, cements, and glues; and doubtless some of his recipes will be found practically useful. For temperas (vehicles) many recipes are given. There are two kinds of egg tempera deserving attention mentioned, and the practice of painting in the egg tempera, and afterwards glazing in oil-colour. The translator particularly recommends in a note this mode of painting, and quotes from Mr Field's Chromatography the following passage:—"Mr Clover has successfully employed the yolk of egg for sketching in body colours, in the manner and with the entire effect of oil, which sketches being varnished have retained their original purity of hue, more especially in the whites, and flexibility of texture, without a crack, after many years in a London atmosphere." The translator recommends it from her own practice and experience.

We have ourselves, in this Magazine, on a former occasion, spoken of a sort of distemper painting—though to give it that name is not very highly to recommend it. We have, nevertheless, found it very good, and admirably adapted for getting in a subject, as affording means of great rapidity of execution. We allude to the admixture of starch and oil—the less oil the more like distemper will it be; or, we should rather say, fresco, which it much more resembles; but oil may be used with it in any proportion. The starch should be made as for domestic use, with water saturated with borax, and the oil added by degrees, and the whole stirred up together while warm; and, in this medium, the colours should be ground as well as worked. It is curious that here, too, the borax is of use; for it not only enables the oil to mix with the water of the starch, but it gives the starch a consistence and toughness, which without it it never possesses. We have found colours retain their hue and purity remarkably well with this vehicle. The whole bears out equally, but without shining. The second painting may produce any desired richness. It is not unpleasant to paint upon a wet ground made with this vehicle, when the picture and ground will dry and harden together.

There is no colour concerning which we are more at a loss in looking at old pictures, than the blues. Three are mentioned by Cennino—indigo, a cobalt, and ultramarine. With regard to the sparing use of the latter, as the most expensive, some practical hints may be met with. We have often wondered with what blue their deep-toned cool greens were made, as in the landscapes of Gaspar Poussin. It was probably Cennino's azzuro della magna (German blue or cobalt.) Prussian blue is of recent invention. We believe Mr Field considers it a good colour. It is made of so many hues that it is difficult to procure good, and it is said to be affected by iron. We have heard indigo complained of as a fugitive colour; Cennino mentions it for skies with a tempera of glue. He mentions, likewise, a green cobalt, or azzuro della magna. White lead, according to him, may be used with all temperas. He says it is the only white that can be used in pictures; the whites in the old pictures are very pure, so that we may be satisfied of its durability. Many artists have doubted if the white of the best painters was white lead, and many substitutes have been proposed. We may rest assured, by the authority of Cennino, that the fault is not in the lead, but in the vehicle, whenever it changes. There is a letter of Titian's, in which he laments the death of the maker of his white; it was made, therefore, we are to suppose, with particular care, as the principal pigment for light.

Orpiment, which was so much in use in Sir Joshua's time, the ill effects of which is visible in the President's "Holy Family" in our National Gallery, was no great favourite in the olden time. In the note upon this pigment, the translator takes occasion to speak of powdered glass, in reference to a remark of Dr Ure, that powdered glass is mixed with it, which renders it lighter. Mrs Merrifield infers from this, that it, powdered glass, is opaque. Undoubtedly it is so in its dry state, and probably with the glue tempera, which alone, according to Cennino, is its proper vehicle—but mixed with oil it is transparent—and mixed in much body with pigments, will give them great richness, and that degree of transparency, even to pigments rather opaque, which we observe in the substance of the pigments of the best time. China clay, and magnesia too, are opaque in their powdered and dry state, but mixed with the pigments, vary their power ad libitum, precisely by the transparency they afford. These two latter substances have likewise a corrective quality upon oils, and we are assured by Mr Coathupe, and have certainly found it to be so, that magnesia is a dryer. We have boiled magnesia and oil together, very thick and jelly-like, and leaving the pipkin exposed, have been surprised to find no skin upon the surface. Mrs Merrifield certainly errs in thinking glass, when mixed with oils, opaque. The blacks of Cennino are from a stone, and opaque; from vine tendrils, ("very black and transparent;") from skins of almonds and kernels of peaches, ("a perfect and fine black;") and lamp black, from the smoke of linseed oil. Mr Field observes, that all carbonaceous blacks mixed with white have a preserving influence upon colours, owing chemically to the bleaching power of carbon, and chromatically to the neutralizing and contrasting power of black with white. Leonardo da Vinci in his palette, the account of which is so unfortunately broken off for lack of paper, mentions the mixing every colour with black. Yet we have met with many painters who totally reject it, and fancy it makes their pictures black. This is very absurd, for black mixed with any other pigment ceases to be black; and an artist may paint very black pictures without the use of that pigment. What Titian recommends, one who would be a colourist need not reject. It seems there was of old much caution that iron should not touch the colours. Yet there is, we believe, much iron in ochres. Mr Coathupe has clearly shown, that even Naples yellow does not suffer from contact with iron, otherwise than by abrasion, by which the steel of the knife becomes itself a pigment, as on the hone. Modern science has much enlarged the colour list. There is thus the greater temptation offered to make endless varieties. It has been remarked in language, that the best writers have the most brief vocabulary—so it may be, that the best colourists will have the fewest colours. The rule has been verified in the old masters of the best time. Cennino Cennini, who always begins from the beginning, recommends drawing with the pen—his pen, for that also he tells you how to make, had no slit. O days of Perryian innovation! It was very well, a vast improvement, almost equal to that of adding the shirt to the ruffles, to invent one slit—we have them now with two and with three.

Very strict studies in anatomy were not much in vogue among the early painters. Our author recommends drawing from nature, and lays down his canon of proportions of the human body, which will be little heeded by our academies. The old Italian is not very complimentary to the sex. Mr Etty will open his eyes with alarm, to find he has been practising all his life in a wrong direction, when he reads "leave that of woman, for there are none perfectly proportioned." We are not quite certain, if some of Mr Etty's stay-spoiled figures are taken for examples, but that the opinion of the old Italian may be in some credit. We spoke in the commencement of this paper, of the "Gummi Fornis," which M. Merimée concluded to be copal. The translator, in a note, offers a conjecture, not without its probability, that it may have been sandarac, the "Vernice da Scrivere" of Cennino, and quotes Raffaello Borghini in his "Reposo." If you would have your varnish brilliant, use much sandarac—it makes certainly a very hard varnish—it is difficult to combine it with oil. We suppose it to have been one of the condemned novelties as a vehicle for painting, from its being included in the condemned list of trash, as only fit to polish boots, that moved the satirical pen of Boschini:—

"O de che strazze se fa cavedal!D'ogio d'avezzo, mastice e sandraca,E trementina (per no dir triaca)Robe che ilusterave ogni stival."Marco Boschini.

Much has been said of late of "Encaustic Painting." It must have been discontinued before the time of Giotto, as shown by the experiments of Lanzi—no wax has been found in pictures painted after the year 1360. We know that Sir Joshua Reynolds frequently used it, as have some painters since his day. We cannot suppose that, mixed with oil, it would ever give pigments their proper hardness.

Dryers are not mentioned by Cennino, excepting verderame (verdigris,) and that as a mordant. How were the oils made to dry? Will the sun be sufficient? In the summers in Italy their mixed oils readily dry. But in Holland, as in England, for at least a great part of the year, they will not dry of themselves; and it is certain that the longer the pigments are subjected to the action of the oil, the greater is the change. White lead is by no means the best drying colour; and if lead, as a dryer, is so injurious as some will have it to be, to colours in general, why do we not find it so in white lead? Cennino recommends garlic pounded to a juice, and cleared, as a mordant. It is supposed that it gives a drying quality to oil. The practice of the old masters in drying their pictures in the sun—was it only to effect the drying? We believe exposure to the atmosphere is most beneficial to newly painted pictures. We have now a picture before us which was disagreeably oily, and yet did not well bear out. We laid it on the grass, face uppermost, where it lay for about ten days during heat and cold, day and night, dry weather and wet, and in some few burning days exposed to the sun; during these hot days, we had it frequently, plentifully washed with water, left on for the sun to take up. We have this day removed the picture to the easel. The "oily appearance" was gone, it was very dry, but pure, and clean, and bore out equally, but rather like distemper. It is a question worth considering, whether the atmosphere did not take up the impurities of the oil, which always come to the surface.

There is proof enough of this. A picture, unless it be painted with very little oil indeed, will become, in a few days after being painted, greasy—it will not take water on the surface—in fact, "secca teme acqua" will not bear water. If, in this state, the surface be lightly rubbed over with common sand and water, this greasiness will be removed, and the surface will not only be clean, but beautiful; this greasiness will, however, in a day or two come again. If the process of sanding be repeated, until the greasiness does not come again, we conjecture that we have done for the picture what time, but a long time, might do—we have removed all the impurity of the oil. We believe that pictures after that do not undergo further change, and if the paint be tolerably hard, may be varnished—and that they will become much sooner hard; for it is more than probable that this greasiness in the oil is the main cause of retarding the drying. We have followed this practice many years, and always with the same results. It is surprising how soon after painting you may sand—even coarse red sand will not remove paint, that is yet tacky—it much remedies the "colori olcesi." The translator lays much stress in the preface upon the importance of white grounds. In the olden time, it appears, that when they were not of gold, they were white; and Leonardo da Vinci thus lays down his precept—"Sempre a quelli colori che vuoi che habino belleza preparerai primo il campo candidissimo, e questo dico de' colori che sono transparenti, perche a quelli che non sono transparenti non giova campo chiaro." And yet Leonardo is said to have painted occasionally on the canvass without any other priming than a coat of glue. His pictures so painted are said to be durable, and worthy his great name. We should have doubted if Titian did always paint on a white ground—and should fix upon the "Peter Martyr" as the subject of doubt. It is said to have been the practice of Correggio; if so, he did not always derive the benefit from the ground which white grounds are said to confer, for his painting is so generally solid, and the transparency so much the effect of his glazing, that there seems to be no reason why he should have given the preference. It is said the Flemish School used white grounds—probably Rubens did so generally, not all other painters. Teniers used a light drab, and, if we were to judge from some of his skies, painted upon it when that thinly coloured ground was wet. Unless a great body of colour be used, even in the most transparent painting, white grounds are apt to give a weakness and flimsiness. Gaspar Poussin, and perhaps generally, Nicolo, painted on red grounds; the former probably often upon a vermilion ground, though most commonly on one of a deeper tone; the advantage of this, in landscapes, such as his, is evident. There is no colour so good as red to set off greens; and in fact, to make tints appear green, that on another ground would not so be; and, moreover, a red ground, from its warmth, makes those greens appear cool, deep, and refreshing, which is so strong a characteristic in the colouring of that great Italian landscape painter, Gaspar Poussin.