THE ART DETECTIVE.

Auckland Star, Volume LXI, Issue 162, 11 July 1930, Page 9

THE ART DETECTIVE.

SCIENCE AIDS EXPERT. HOW BOGUS OLD MASTERS ARE RECOGNISED. VALUE OF MICRO-PHOTOGRAPHY. The discovery in Paris of a wholesale manufactory of fake pictures makes it more than ever evident that the assistance of the scientist in deciding the authenticity of a picture is now almost essential The most competent expert can be deceived, as has been proved time and again, but the scientist with the X-rays, microscopic lens and chemical analysis of pigments is now in a position to come to conclusions which, as a rule, are unassailable. The two Rembrandt portraits lent to the Dutch Exhibition by the Duke of Westminster, the authenticity of -which was challenged by a well-known critic, were definitely proved by scientific means, to be excellent examples of Rembrandt's earlier work. It is, moreover, unnecessary for the scientist to supplant entirely the recognised expert, who, with years of experience and a long artistic training, will alwaj's have the last word. Rather will the results of scientific investigation be a valuable and often definite means of confirmation.

Chemical Analysis. Professor A. P. Laurie, Professor of Chemistry to the Eoyal Academy, has, ■perhaps done more than any man to defeat the maker of spurious pictures. Years of experiment have enabled him to tabulate the pigments used by artists of every period, and from his list can be conclusively established whether a certain colour was in use at a certain time and when certains colours fell into disuse. The process only necessitates the taking of a few minute fragments of the pigment of a picture, and by submitting it to chemical analysis the date of a painting can be fairly accurately arrived at. Microscopic examination of the pigments is another method followed by Professor Laurie. By this means it can be definitely established whether a picture has been retouched. The discovery of certain colours which were known to be in use by a particulai artist is additional evidence of a picture's quite apart from the ordinary expert's judgment. By this means the authenticity of a reputed early 16th century Italian picture was definitely disproved by the discovery upon it of pigment invented only in the 17th century. Micro-Photography. Perhaps the most valuable and conelusive of Professor Laurie's labours is his system qj micro-photography. By means of enlarged photographs of sections of a painting remarkably definite conclusions can be arrived at from the technique and brushwork of the artist which are thus shown so clearly. These pictures can be projected on to a screen by means of a lantern, and every detail of a painting's structure closely compared side by side with similar photos of sections of an accepted work by the same artist. Micro-photography is especially valuable when examining pictures attributed to such artists as Teniers and VVatteau, whose touches are so fine as to be beyond the limits of unaided sight. All this undoubtedly marks a great step towards defeating the machinations of the picture forger.

Face Painted Over. It defeats the efforts of the maquilleur, whose speciality is the painting over of an ugly or unprepossessing face in a portrait, and replacing it by one of a more pleasing character. The trucqueur, the maker of composite pictures, must also look to Ms laurels. His method, should a Titian be required, is to carefully copy a head from one well-known work, an arm from another, and so on, and thus build up a picture to which, he gives an appropriate title. Finally, before offering it for sale, he robs it of its "newness" with the aid of soot, varnish, tobacco-ash and lampblack. Such works, by their sheer cleverness, have at times deceived the ordinary expert, but the most cursory examination would disclose the fraud to the scientist. Aid of Rontgen Rays. The X-ray and ultra-violet ray, too, have proved of inestimable value in proving or disproving the authenticity uf pictures. By the help of the, Rontgen ray it can at once be discovered whether the pigments of a picture are old or modern. Much, however, has yet to be done before the collector is immune from the wiles of the picture forger. , The scientist is not infallible, and his conclusions have at times been definitely upset by the man with a technical knowledge of art. The ideal expert of the future will be a man who combines the* necessary scientific knowledge with a familiarity with the technique of the art of paint-

m - In Peru it was once the custom for domestic servants to have two of their upper front teeth extracted. Their absence indicated servitude. An apple tree one hundred years old is a rarity, but a pear tree of two or three hundred years is not uncommon.