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X-rays authenticate raphael masterpiece
X-RAYS AUTHENTICATE RAPHAEL MASTERPIECE K o d a k i n d u s t r i a l x - r a y f i l m , ' I n d u s t r e x ' D, w a s u s e d by N a t i o n a l G a l l e r y s t a f f in London to p r o d u c e a r a d i o g r a p h y m o s a i c t h a t h e l p e d to p r o v e - c o n t r a r y to w h a t had b e e n thought f o r m a n y y e a r s - - t h a t the L o n d o n h e l d R a p h a e l p a i n t i n g of P o p e J u l i u s w a s t h e o r i g i n a l w o r k and t h a t t h e Uffizi G a l l e r y in F l o r e n c e w a s d i s p l a y i n g the copy. T h e n i n e - r a d i o g r a p h m o s a i c i s now on show w i t h t h e p a i n t i n g at t h e N a t i o n a l G a l l e r y for comparison.
T h e u s e of r a d i o g r a p h y in the s t u d y of w o r k s of a r t i s not a new d e v e l o p m e n t and h a s b e e n u s e d to i d e n t i f y p a i n t i n g s s i n c e t h e f i r s t w o r l d w a r . By p e n e t r a t i n g b e l o w the s u r f a c e , r a d i o g r a p h y r e v e a l s t h e o r i g i n a l i d e a s of the a r t i s t ; by m a k i n g d i f f e r e n t r a d i o g r a p h s , d e t a i l s of s u b s e q u e n t c h a n g e s c a n c o m e to light. T h e r e - u s e of c a n v a s s e s , r e p a i r s to d a m a g e d a r e a s , and a l t e r a t i o n s by o t h e r a r t i s t s a r e a l s o r e v e a l e d . A d e t a i l e d s t u d y c a n go f u r t h e r , p r o v i d i n g i n f o r m a t i o n on t h e t e c h n i q u e s , p a i n t i n g m a t e r i a l s and s t r u c t u r e of t h e artist' s work. R a d i o g r a p h y c a n h e l p d a t e unknown w o r k s , i n d i c a t e the p e r i o d o r even the a r t i s t s . T h e c o n s t i t u e n t s of p a i n t s c a n b e i d e n t i f i e d by r a d i o g r a p h y b e c a u s e the e l e m e n t s of the p i g m e n t s a b s o r b r a d i a t i o n d i f f e r e n t i a l l y . H e a v y a t o m s l i k e l e a d ( p r e s e n t in f l a k e w h i t e and m i n i u m ) and m e r c u r y (a c o n s t i t u e n t of v e r m i l i o n ) a b s o r b x - r a y s m o r e s t r o n g l y than l i g h t a t o m s w h i c h c o m p o s e the o r g a n i c p i g m e n t s of p a i n t s . A t h o r o u g h r a d i o g r a p h i c e x a m i n a t i o n of the R a p h a e l w a s c a r r i e d out and i m m e d i a t e l y r e v e a l e d ' p e n t i m e n t i ' --the a r t i s t ' s f i r s t t h o u g h t s - - t h a t had l a t e r b e e n p a i n t e d o v e r . T h e r a d i o g r a p h ( F i g 3) showed that the p a p a l e m b l e m s of golden c r o s s e d k e y s in the b a c k g r o u n d , had o r i g i n a l l y b e e n in d i f f e r e n t p o s i t i o n s , and a n u m b e r of t h e m had b e e n p a i n t e d out c o m p l e t e l y . A r m e d w i t h r a d i o g r a p h i c e v i d e n c e , the N a t i o n a l Gallery re-studied the documentary evidence relating to t h e o r i g i n a l and i t s m o v e m e n t s s i n c e the 16th c e n t u r y and f i n a l l y a s k e d the Uffizi G a l l e r y in F l o r e n c e to r a d i o g r a p h t h e i r v e r s i o n . A f t e r c o n s i d e r a b l y d e l a y , t h i s w a s done, and the r e s u l t s s h o w e d no p e n t i m e n t i and s o c o n f i r m e d the a u t h e n t i c i t y of the N a t i o n a l G a l l e r y p a i n t i n g w h i c h h a s now b e e n a l l o c a t e d a s p e c i a l r o o m of i t s o w n - - w o r t h y of a w o r k of a r t w h o s e v a l u e r o s e o v e r n i g h t f r o m f o u r to s e v e n f i g u r e s . K o d a k L i m i t e d , Kodak House, K i n g s w a y , L o n d o n WC2
D O M E S T I C Q U A L I T Y ASSURANCE
Fig 3
One of nine Kodak radiograplm which helped to prove the authenticity of the Raphael painting of Pope Julius. Here, in the top left hand corner and in the centre, two of the c r o s s e d k e y s papal e m b l e m s are visible
R a d i o g r a p h y of the R a p h a e l p a i n t i n g g o e s b a c k to b e f o r e t h e 1950s when an x - r a y of t h e h e a d of P o p e J u l i u s w a s m a d e but d i d not show w h a t l a t e r r a d i o g r a p h s would r e v e a l . B e c a u s e of t h e d i f f i c u l t y of x r a y i n g a l a r g e p i c t u r e a l l in one go, it i s c u s t o m a r y to s e l e c t k e y a r e a s . T h e h e a d w a s the o b v i o u s one, but t h e w r o n g one a s it t u r n e d out. It w a s not u n t i l l a s t y e a r t h a t t h e f i r s t r e a l i n v e s t i g a t i o n w a s begun. It had b e e n s u g g e s t e d to the N a t i o n a l G a l l e r y t h a t t h e r e w a s s o m e doubt about the p a i n t i n g in F l o r e n c e , and t h a t f u r t h e r c h e c k s could be w o r t h m a k i n g in London.
H e a t i n g e l e m e n t s f o r a p p l i a n c e s such a s e l e c t r i c k e t t l e s , c o o k e r r i n g s and i m m e r s i o n h e a t e r s have a p r o t e c t i v e o u t e r s h e a t h of s p e c i a l h e a t - r e s i s t a n t s t a i n l e s s s t e e l tubing. The B a c k e r E l e c t r i c Co L t d ( R o t h e r h a m ) p r o d u c e a r a n g e of s u c h tubing and t e s t it o n - l i n e . The e q u i p m e n t i n s t a l l e d to p e r f o r m t h i s q u a l i t y m o n i t o r i n g i s the L o c k Mk V E d d y t e s t e r , an eddy c u r r e n t i n s p e c t i o n s y s t e m u s e d to d e t e c t s m a l l f l a w s in t u b e , r o d o r w i r e . It a l l o w s off- o r o n - l i n e t e s t i n g of f e r r o u s o r n o n - f e r r o u s m e t a l s , with a m a x i m u m i n s p e c tion r a t e u s u a l l y w e l l in a d v a n c e of the a s s o c i a t e d mechanical handling speeds. Advanced signal proc e s s i n g t e c h n i q u e s r e s u l t in i n c r e a s e d s e n s i t i v i t y t h r o u g h the r e d u c t i o n of n o i s e , an i m p o r t a n t d e v e l o p m e n t which h a s i m p l i c a t i o n s f o r the d e s i g n of the s e a r c h coil s y s t e m . It b e c a m e p o s s i b l e to a l l o w a g r e a t e r c l e a r a n c e b e t w e e n the c o i l s and the m a t e r i a l b e i n g t e s t e d , g i v i n g g r e a t e r e a s e of handling and a r e d u c e d r i s k of d a m a g e to c o i l o r m a t e r i a l . F o r the t e s t i n g of f e r r o u s m a t e r i a l s , m a g n e t i c s a t u r a t i o n from a permanent or electro-magnet assembly is used.
n o n - d e s t r u c t i v e t e s t i n g O c t o b e r 1970
333
T h e u s e of r a d i o g r a p h y in the s t u d y of w o r k s of a r t i s not a new d e v e l o p m e n t and h a s b e e n u s e d to i d e n t i f y p a i n t i n g s s i n c e t h e f i r s t w o r l d w a r . By p e n e t r a t i n g b e l o w the s u r f a c e , r a d i o g r a p h y r e v e a l s t h e o r i g i n a l i d e a s of the a r t i s t ; by m a k i n g d i f f e r e n t r a d i o g r a p h s , d e t a i l s of s u b s e q u e n t c h a n g e s c a n c o m e to light. T h e r e - u s e of c a n v a s s e s , r e p a i r s to d a m a g e d a r e a s , and a l t e r a t i o n s by o t h e r a r t i s t s a r e a l s o r e v e a l e d . A d e t a i l e d s t u d y c a n go f u r t h e r , p r o v i d i n g i n f o r m a t i o n on t h e t e c h n i q u e s , p a i n t i n g m a t e r i a l s and s t r u c t u r e of t h e artist' s work. R a d i o g r a p h y c a n h e l p d a t e unknown w o r k s , i n d i c a t e the p e r i o d o r even the a r t i s t s . T h e c o n s t i t u e n t s of p a i n t s c a n b e i d e n t i f i e d by r a d i o g r a p h y b e c a u s e the e l e m e n t s of the p i g m e n t s a b s o r b r a d i a t i o n d i f f e r e n t i a l l y . H e a v y a t o m s l i k e l e a d ( p r e s e n t in f l a k e w h i t e and m i n i u m ) and m e r c u r y (a c o n s t i t u e n t of v e r m i l i o n ) a b s o r b x - r a y s m o r e s t r o n g l y than l i g h t a t o m s w h i c h c o m p o s e the o r g a n i c p i g m e n t s of p a i n t s . A t h o r o u g h r a d i o g r a p h i c e x a m i n a t i o n of the R a p h a e l w a s c a r r i e d out and i m m e d i a t e l y r e v e a l e d ' p e n t i m e n t i ' --the a r t i s t ' s f i r s t t h o u g h t s - - t h a t had l a t e r b e e n p a i n t e d o v e r . T h e r a d i o g r a p h ( F i g 3) showed that the p a p a l e m b l e m s of golden c r o s s e d k e y s in the b a c k g r o u n d , had o r i g i n a l l y b e e n in d i f f e r e n t p o s i t i o n s , and a n u m b e r of t h e m had b e e n p a i n t e d out c o m p l e t e l y . A r m e d w i t h r a d i o g r a p h i c e v i d e n c e , the N a t i o n a l Gallery re-studied the documentary evidence relating to t h e o r i g i n a l and i t s m o v e m e n t s s i n c e the 16th c e n t u r y and f i n a l l y a s k e d the Uffizi G a l l e r y in F l o r e n c e to r a d i o g r a p h t h e i r v e r s i o n . A f t e r c o n s i d e r a b l y d e l a y , t h i s w a s done, and the r e s u l t s s h o w e d no p e n t i m e n t i and s o c o n f i r m e d the a u t h e n t i c i t y of the N a t i o n a l G a l l e r y p a i n t i n g w h i c h h a s now b e e n a l l o c a t e d a s p e c i a l r o o m of i t s o w n - - w o r t h y of a w o r k of a r t w h o s e v a l u e r o s e o v e r n i g h t f r o m f o u r to s e v e n f i g u r e s . K o d a k L i m i t e d , Kodak House, K i n g s w a y , L o n d o n WC2
D O M E S T I C Q U A L I T Y ASSURANCE
Fig 3
One of nine Kodak radiograplm which helped to prove the authenticity of the Raphael painting of Pope Julius. Here, in the top left hand corner and in the centre, two of the c r o s s e d k e y s papal e m b l e m s are visible
R a d i o g r a p h y of the R a p h a e l p a i n t i n g g o e s b a c k to b e f o r e t h e 1950s when an x - r a y of t h e h e a d of P o p e J u l i u s w a s m a d e but d i d not show w h a t l a t e r r a d i o g r a p h s would r e v e a l . B e c a u s e of t h e d i f f i c u l t y of x r a y i n g a l a r g e p i c t u r e a l l in one go, it i s c u s t o m a r y to s e l e c t k e y a r e a s . T h e h e a d w a s the o b v i o u s one, but t h e w r o n g one a s it t u r n e d out. It w a s not u n t i l l a s t y e a r t h a t t h e f i r s t r e a l i n v e s t i g a t i o n w a s begun. It had b e e n s u g g e s t e d to the N a t i o n a l G a l l e r y t h a t t h e r e w a s s o m e doubt about the p a i n t i n g in F l o r e n c e , and t h a t f u r t h e r c h e c k s could be w o r t h m a k i n g in London.
H e a t i n g e l e m e n t s f o r a p p l i a n c e s such a s e l e c t r i c k e t t l e s , c o o k e r r i n g s and i m m e r s i o n h e a t e r s have a p r o t e c t i v e o u t e r s h e a t h of s p e c i a l h e a t - r e s i s t a n t s t a i n l e s s s t e e l tubing. The B a c k e r E l e c t r i c Co L t d ( R o t h e r h a m ) p r o d u c e a r a n g e of s u c h tubing and t e s t it o n - l i n e . The e q u i p m e n t i n s t a l l e d to p e r f o r m t h i s q u a l i t y m o n i t o r i n g i s the L o c k Mk V E d d y t e s t e r , an eddy c u r r e n t i n s p e c t i o n s y s t e m u s e d to d e t e c t s m a l l f l a w s in t u b e , r o d o r w i r e . It a l l o w s off- o r o n - l i n e t e s t i n g of f e r r o u s o r n o n - f e r r o u s m e t a l s , with a m a x i m u m i n s p e c tion r a t e u s u a l l y w e l l in a d v a n c e of the a s s o c i a t e d mechanical handling speeds. Advanced signal proc e s s i n g t e c h n i q u e s r e s u l t in i n c r e a s e d s e n s i t i v i t y t h r o u g h the r e d u c t i o n of n o i s e , an i m p o r t a n t d e v e l o p m e n t which h a s i m p l i c a t i o n s f o r the d e s i g n of the s e a r c h coil s y s t e m . It b e c a m e p o s s i b l e to a l l o w a g r e a t e r c l e a r a n c e b e t w e e n the c o i l s and the m a t e r i a l b e i n g t e s t e d , g i v i n g g r e a t e r e a s e of handling and a r e d u c e d r i s k of d a m a g e to c o i l o r m a t e r i a l . F o r the t e s t i n g of f e r r o u s m a t e r i a l s , m a g n e t i c s a t u r a t i o n from a permanent or electro-magnet assembly is used.
n o n - d e s t r u c t i v e t e s t i n g O c t o b e r 1970
333