Neutron Activation Analytical Survey of Some Intact Medieval Glass

7 Neutron Activation Analytical Survey of

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Some Intact Medieval Glass Panels and Related Specimens JACQUELINE S. OLIN Conservation-Analytical Laboratory, Smithsonian Institution, Washington, D. C. 20560 EDWARD V. SAYRE Brookhaven National Laboratory, Upton, Ν. Y. 11973 The concentrations of 15 component oxides in medieval window glass were determined by instrumental thermal neutron activation analysis. Three groups of glass were studied: 52 specimens from a set of seven thirteenth-century French grisaille panels from a now demolished royal cha teau at Rouen; 10 samples from a grisaille panel in the collection of the Princeton Museum; and a set of 32 random fragments of varied provenance. Significantly differing compositions were found. However the specimens from within individual and related groups of panels are compositionally similar even for different colors of glass. This similarity, therefore, indicates a common origin for the related pieces. Six of the random specimens had the same basic formulation as the specimens from the Rouen chateau panels. /

^ p h e extent to w h i c h s t a i n e d glass panels o f t h e M i d d l e A g e s h a v e b e e n A

r e m o v e d f r o m t h e i r o r i g i n a l settings i n chapels a n d c a t h e d r a l s , d i s

m a n t l e d , a n d r e c o n s t r u c t e d w i t h other glass to f o r m n e w panels w h o s e p r o v e n a n c e m u s t b e e s t a b l i s h e d a n d the r e s t o r a t i o n pieces i d e n t i f i e d is often n o t a p p r e c i a t e d .

A w i n d o w i n the P r i n c e t o n U n i v e r s i t y M u s e u m

of A r t is a n excellent e x a m p l e of s u c h r e c o n s t r u c t i o n .

The Princeton

w i n d o w depicts the m a r t y r d o m of S a i n t G e o r g e ( F i g u r e 1 ). I t w a s p u r c h a s e d f o r t h e art m u s e u m b y t h e f o r m e r D i r e c t o r , F r a n k J e w e t t M a t h e r , J r . i n 1924. A s i m i l a r w i n d o w s h o w i n g S a i n t G e o r g e b o u n d to a w h e e l w a s d o n a t e d to C h a r t r e s C a t h e d r a l b y e i t h e r G u i l l a u m e or R o b e r t d e 100 Beck; Archaeological Chemistry Advances in Chemistry; American Chemical Society: Washington, DC, 1974.

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Glass

Figure 1. Stained ghss from Chartres Cathedral (in the Museum of Art, Princeton University). The top left quarter is from a thirteenth-century window depicting the martyrdom of St. George. Accession No. 71. C o u t e n a y d u r i n g the second d e c a d e of the t h i r t e e n t h c e n t u r y ( 1 ).

The

C h a r t r e s w i n d o w r e m a i n e d there u n t i l 1788 w h e n t h e s c u l p t o r B r i d a n p e t i t i o n e d its r e m o v a l to a l l o w m o r e l i g h t to f a l l o n his w o r k o n

the

n e w h i g h altar.

the

T h e r e is no d i r e c t r e c o r d of w h a t h a p p e n e d

Chartres w i n d o w ,

but modern

grisailles n o w

fill

the

space.

to

Several

studies of the P r i n c e t o n w i n d o w w e r e p u b l i s h e d b y W . F r e d e r i c k S t o h l m a n a n d b y H e n r y G r a h a m (2, 3, 4, 5 ) ; they c o n c l u d e d that o n l y the t o p left q u a r t e r is o r i g i n a l glass, a n d t h a t i t a n d a p a n e l w h i c h r e m a i n s at C h a r t r e s ( F i g u r e 2 ) as p a r t of a c o m p o s i t e of panels w e r e o n c e together at C h a r t r e s i n the d e C o u r t e n a y w i n d o w .

T h e p o s s i b l e l o c a t i o n of t w o

quarters of the d e C o u r t e n a y w i n d o w is s t i l l u n k n o w n . T h i s is a n e x a m p l e of the c o m p l e x i t y w h i c h c a n exist i n s t u d y i n g t h i r t e e n t h c e n t u r y glass windows. A l a r g e p o r t i o n , p o s s i b l y a l l , of the glass o r i g i n a l l y i n a m e d i e v a l w i n d o w w o u l d p r o b a b l y h a v e b e e n p r o d u c e d b y a single w o r k s h o p .

Of

course, s p e c i a l colors a n d types of glass m a y h a v e b e e n b r o u g h t i n f r o m other sources s p e c i a l i z i n g i n t h e i r p r o d u c t i o n .

H o w e v e r , i t is u n l i k e l y

that the same t y p e of glass—e.g., g r i s a i l l e — i n a single p a n e l o r i g i n a l l y w o u l d h a v e m a n y sources.

G l a s s p r o d u c e d b y a single source of m a n u -

Beck; Archaeological Chemistry Advances in Chemistry; American Chemical Society: Washington, DC, 1974.

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ARCHAEOLOGICAL

CHEMISTRY

Figure 2. Thirteenth-century grisaille panels in the collection of The Cloisters Museum, New York. The panels came from the chateau of Rouen. Accession No. 69.236.2. Analytical data are in Table II. The numbers on the photograph correspond to sample numbers in the table.

Figure 3.

Accession No. 69.236.3 (see Figure 2)


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Figure 4.


Figure 5.



103

104

ARCHAEOLOGICAL CHEMISTRY

f a c t u r e at a g i v e n t i m e w o u l d p r o b a b l y h a v e c o m p o s i t i o n , a n d h o p e f u l l y this c o m p o s i t i o n f r o m t h a t of glass p r o d u c e d elsewhere.

b e e n consistent i n its

w o u l d differ s i g n i f i c a n t l y

T h e u n i f o r m i t y of glass f r o m a

g i v e n s o u r c e c a n be s t u d i e d w e l l b y m u l t i p l e s a m p l i n g of

individual

panels because the l i k e l i h o o d of e n c o u n t e r i n g glass of r e l a t e d origins w i t h i n t h e m is great e v e n i f later changes w e r e m a d e . It is l i k e l y not o n l y that glass of the same m a n u f a c t u r e r w i l l b e f o u n d i n a single p a n e l b u t that separate fragments of i n d i v i d u a l glass p r e p a r a tions w i l l b e e n c o u n t e r e d .

S u c h pieces s h o u l d b e v e r y closely r e l a t e d i n

c o m p o s i t i o n a n d h e n c e c o u l d b e separated t h r o u g h analysis. T h e extent a n d n a t u r e of s u c h close c o r r e l a t i o n s h o u l d i n d i c a t e the size a n d u n i f o r m i t y of i n d i v i d u a l batches.

Figure 6.


T h i s s t u d y w a s d o n e to establish w h e t h e r s u c h correlations d o exist and

whether

the

distinctiveness of

sources of glass m a n u f a c t u r e w i l l

glass

composition

from

different

a l l o w m e a n i n g f u l i n t e r p r e t a t i o n of

o b s e r v e d correlations. A l i m i t e d a m o u n t of h i s t o r i c a l i n f o r m a t i o n exists o n the o r g a n i z a t i o n of the w o r k s h o p s w h i c h w e r e the sources of s t a i n e d glass i n m e d i e v a l E u r o p e . I n " A H i s t o r y of T e c h n o l o g y " b y S i n g e r et al. reference is m a d e to T h e V e n e r a b l e B e d e w h o i n the e i g h t h c e n t u r y stated i n his " H i s t o r i a A b l a t u m , " that t h e F r e n c h glaziers not o n l y d i d the w o r k r e q u i r e d b u t t a u g h t the E n g l i s h h o w to do it. F r e q u e n t refer ence is m a d e to the g l a z i n g of the c h u r c h w i n d o w s at M o n k w e a r m o u t h ,


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Figure 7.


Figure 8.



105

106


England by

F r e n c h craftsmen w h o

a r r i v e d i n 675 A . D .

Samples

of

w i n d o w glass f r o m t h e m o n a s t i c site at M o n k w e a r m o u t h h a v e

been

excavated a n d analyzed b y electron probe

oxide

(6).

Their sodium

concentrations r a n g e f r o m 13.7 to 1 6 . 1 % , a n d p o t a s s i u m o x i d e trations range f r o m 0.24 to 1 . 1 2 % .

concen

T h e s e alkalies are present i n this

glass i n n e a r l y t h e same p r o p o r t i o n s as i n a n c i e n t R o m a n glass ( 7 ) .

In

contrast, m u c h of later m e d i e v a l glass has b e e n f o u n d b y G e i l m a n n a n d others

(8)

to h a v e p r e d o m i n a n t l y a p o t a s s i u m r a t h e r t h a n a s o d i u m

c o m p o s i t i o n . O n t h e basis of this a n d other c o m p o s i t i o n a l considerations i t has u s u a l l y b e e n c o n c l u d e d that w o o d

ash w a s the m a i n source

of

a l k a l i i n l a t e m e d i e v a l glass.

Figure 9. Thirteenth-century grisaille panel in the collection of the Museum of Art, Princeton University. Accession No. 43-65. Analytical data in Table V. The numbers on the photographs correspond to sample numbers in the table.

W h a t w e k n o w of the t e c h n i q u e s of glass m a k i n g d u r i n g the M i d d l e A g e s comes m a i n l y f r o m the d e s c r i p t i o n b y T h e o p h i l u s ( 9 ) .

According

to h i m t w o parts of b e e c h w o o d ashes a n d one p a r t s a n d w e r e m i x e d t h o r o u g h l y a n d p l a c e d i n a f u r n a c e to b e f r i t t e d .

T h e fritted mixture

w a s d i s t r i b u t e d to w h i t e c l a y pots w h i c h w e r e fired to m e l t the glass.


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Procedure

T w o p r o c e d u r e s of s a m p l e a c t i v a t i o n w e r e u s e d i n these analyses. I n t h e first, samples of ca. 20 m g w e r e w e i g h e d a n d heat-sealed i n p o l y e t h y l e n e t u b i n g for a 20-sec a c t i v a t i o n at a flux of 1.5 Χ 1 0 neutrons c m " sec" i n the V l l f a c i l i t y of the h i g h flux b e a m reactor at B r o o k h a v e n National Laboratory. M n w a s c o u n t e d after a b o u t 4 h r s , a n d the Na and K w e r e c o u n t e d after 24 hrs. A s e c o n d g r o u p of 5 0 - m g samples w a s a c t i v a t e d for 16 hrs at a flux of 1.5 Χ 1 0 neutrons c m " sec" . A f t e r a b o u t t w o weeks the samples w e r e p o u r e d f r o m a l u m i n u m to glass v i a l s for c o u n t i n g . T h e contents of the a l u m i n u m vials w e r e w a s h e d i n t o glass v i a l s w i t h e t h y l a l c o h o l for q u a n t i t a t i v e transfer. T h e s e samples w e r e c o u n t e d for δΌ-ΙΟΟ m i n for a l l other elements, u s i n g a n a u t o m a t i c s a m p l e changer. 14

2

1

5 6

2 4

4 2

14

2

1

I n the second p r o c e d u r e , one s a m p l e of ca. 40 m g w a s a c t i v a t e d t w i c e . T h e s a m p l e was first p l a c e d i n a p o l y e t h y l e n e v i a l a n d a c t i v a t e d for 20 sec i n the V l l f a c i l i t y at a flux of 1.5 Χ 1 0 neutrons c m " sec" . A f t e r c o u n t i n g , the samples w e r e t r a n s f e r r e d to q u a r t z v i a l s , r e w e i g h e d , a c t i v a t e d for 7 hrs at a flux of 2.8 Χ 1 0 neutrons c m " sec" or 16 hrs at 1.5 Χ 1 0 neutrons c m " sec" , a n d r e c o u n t e d i n the q u a r t z containers. 14

14

14

2

2

2

1

1

1

I n b o t h p r o c e d u r e s , s t a n d a r d U . S . G e o l o g i c a l S u r v e y rocks G - 2 , G S P - 1 , A G V - 1 , B C R - 1 , P C C - 1 , a n d D T S - 1 were weighed w i t h each g r o u p of glass samples. T h u s , glass samples a n d s t a n d a r d samples of s i m i l a r w e i g h t w e r e a c t i v a t e d a n d c o u n t e d s i m u l t a n e o u s l y . S i n c e these r o c k standards c o n t a i n e d m e a s u r a b l e a m o u n t s of a l l the elements deter m i n e d i n the glasses, t h e y s e r v e d as e l e m e n t - b y - e l e m e n t m o n i t o r s of t h e n e u t r o n flux densities a n d c o u n t i n g geometries e n c o u n t e r e d . F o r the r o c k standards w e u s e d t h e averages of a l l d e t e r m i n a t i o n s r e p o r t e d after s i g n i ficantly d e v i a n t values h a d b e e n e l i m i n a t e d b y C h a u v e n e t s c r i t e r i o n . F o r consistency w e c o n v e r t e d a l l e l e m e n t a l concentrations to o x i d e c o n centrations. T h e samples w e r e c o u n t e d u s i n g a 3 5 - m l G e ( L i ) detector; t w o 1600-channel S C I P P a n a l y z e r s w h i c h c o u l d b e c o n n e c t e d i n series to produce a 3 2 0 0 - c h a n n e l s p e c t r a w e r e u s e d for the gamma-ray spectroscopy. T h e d a t a w e r e c o l l e c t e d o n m a g n e t i c t a p e a n d f e d i n t o a C D C 6600 computer where a curve-fitting program, B R U T A L , was applied, B R U T A L o u t p u t g a v e n u m e r i c a l values f o r the p o s i t i o n a n d i n t e g r a t e d i n t e n s i t y of e a c h p e a k c o r r e c t e d f o r b a c k g r o u n d . T h e s e intensities w e r e p u n c h e d o n cards for e a c h n u c l i d e for e a c h s a m p l e a n d s t a n d a r d . U s i n g the C D C 6600 c o m p u t e r ( i n some cases t h e C D C 6400 c o m p u t e r of the S m i t h sonian Institution ) and programs w e have developed a n d n a m e d E L C A L C a n d S A M P C A L C , w e c a l c u l a t e the o x i d e concentrations after c o r r e c t i n g f o r r a d i o i s o t o p e d e c a y i n b o t h standards a n d samples. T h e specific activities of the U . S . G e o l o g i c a l S u r v e y rocks are c a l c u l a t e d b y E L C A L C . T h e y w e r e u s e d w i t h the S A M P C A L C p r o g r a m to c o m p a r e the specific activities of e a c h r a d i o i s o t o p e i n t h e samples a n d to c a l c u l a t e the o x i d e concentrations of the elements m e a s u r e d f r o m these ratios.


108


Panels and Individual

Pieces of Medieval Glass Studied

T h e first g r o u p w e a n a l y z e d represents a n extensive s a m p l i n g — 5 5 glass specimens f r o m seven separate panels f r o m t h e c h a t e a u of R o u e n , b u i l t i n the t h i r t e e n t h c e n t u r y as a p r o v i n c i a l residence for t h e F r e n c h monarch.

I n the b o r d e r of e a c h p a n e l a p p e a r castles of C a s t i l e , the

w e l l k n o w n i n s i g n i a of Q u e e n B l a n c h e of C a s t i l e , m o t h e r of L o u i s I X . T h e s e panels are s h o w n i n F i g u r e s 2 - 8 , i n w h i c h the s u p e r i m p o s e d n u m bers i n d i c a t e positions f r o m w h i c h samples w e r e r e m o v e d .

T h e chateau

w a s d e m o l i s h e d i n t h e seventeenth c e n t u r y , a n d n i n e of its glass panels are n o w i n the c o l l e c t i o n of T h e C l o i s t e r s M u s e u m . W e s a m p l e d seven of these p a n e l s , A c c e s s i o n N o s . 69.236.2, 3, 4, 5, 6, 7, 8, a n d 10, w h i l e they w e r e d i s a s s e m b l e d for r e l e a d i n g . T h e s e c o n d set consists of 11 samples f r o m g r i s a i l l e fragments i n a p a n e l w h i c h is p a r t of the c o l l e c t i o n of t h e P r i n c e t o n U n i v e r s i t y M u s e u m o f A r t ( A c c e s s i o n N o . 43-65) ( F i g u r e 9 ) .

S a m p l i n g was d o n e w h e n t h e

p a n e l w a s b e i n g r e l e a d e d . A t one t i m e this p a n e l w a s i n the c o l l e c t i o n o f a f o r m e r c u r a t o r of the M e t r o p o l i t a n M u s e u m of A r t , B a s h f o r d D e a n . Table I.

Oxide Concentrations for Miscellaneous Identified Using Accession Percent

Accession

No.

23.229.2-2 23.229.2-3 23.229.2-10 23.229.2-14 23.229.4-1 23.229.4-6 23.229.4-7 23.229.4-10 23.229.5-2 23.229.5-5 23.229.5-6 23.229.5-7 23.229.5-8 23.229.5-9 23.229.5-10 30.73.210 30.73.211 30.73.212 30.73.214 30.73.216 30.73.217 30.73.218 a 6

Na 0

K0

BaO

MnO

0.76 0.30 1.29 0.78 0.21 0.61 1.73 0.68 5.66 19.40 1.95 2.02 3.96 0.88 13.20 2.83 15.00 3.04 1.25 0.63 2.44 1.15

12.4 22.3 16.7 16.0 20.8 12.1 12.0 12.0 4.5 2.4 16.6 18.1 10.6 11.7 2.4 11.4 4.8 12.6 12.7 10.7 11.0 12.7

0.111 0.492 0.181 0.082 0.182 0.090 0.230 0.052 0.186 0.042 0.082 0.220 0.184 0.036 0.241 0.123 0.046 0.179 0.167 0.060 0.124 0.190

0.79 1.83 1.01 0.36 1.01 0.61 1.09 1.26 1.10 0.44 0.74 1.93 1.77 0.74 0.65 0.37 0.51 1.25 0.97 0.40 0.65 1.13

2

2

See Figure 10. N D — N o t determined.


Fe 0 2

3

0.53 0.35 0.81 0.91 0.49 0.69 0.59 0.41 0.83 1.19 0.58 0.48 0.52 0.63 0.72 0.82 1.00 0.46 0.54 1.09 0.84 0.69

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D e a n has p u b l i s h e d p h o t o g r a p h s of this p a n e l ( 1 0 ) , a n d it has also b e e n discussed b y P a u l F r a n k l ( I I ) .

Its specific o r i g i n has n o t b e e n

firmly

e s t a b l i s h e d , b u t a l l w h o s t u d i e d it r e g a r d i t as a n excellent e x a m p l e of t h i r t e e n t h - c e n t u r y g r i s a i l l e glass. T h e final g r o u p consists of 32 pieces of m e d i e v a l glass f r o m v a r i o u s sources w h i c h w e r e p a r t of the c o l l e c t i o n of T h e C l o i s t e r s M u s e u m a n d w e r e d o n a t e d to the C o r n i n g M u s e u m of G l a s s . Since t h e provenances of these specimens are not w e l l e s t a b l i s h e d , the d a t a for t h e m cannot b e u s e d to c h a r a c t e r i z e p a r t i c u l a r structures or glass w o r k s h o p s .

These

samples s h o w the extensive v a r i a t i o n i n c o m p o s i t i o n w h i c h does exist i n m e d i e v a l s t a i n e d glass f r o m different sources.

Some, h o w e v e r , c a n b e

g r o u p e d u p o n the basis of s i m i l a r c o m p o s i t i o n . Sampling

during

Restoration

T h e panels w e r e a l l r e l e a d e d a n d restored b y D i e t e r G o l d k u h l e of R e s t o n , V a . W h e n the i n d i v i d u a l panes w e r e separated, corners of those selected for analysis w e r e c l e a n e d w i t h a t u n g s t e n c a r b i d e b u r r g r i n d i n g Non-Matching Group of Grisaille Fragments Numbers of The Cloisters M u s e u m α

Parts per Rb 0 2

140 460 250 110 530 100 360 200 40 12 360 210 290 81 39 187 42 450 320 182 187 158

Cs 0 2

0.58 2.45 0.17 0.48 3.40 0.69 0.97 1.09 0.45 0.10 1.41 2.24 2.34 0.34 0.17 1.10 0.39 2.35 1.73 1.30 1.20 0.49

Sci0

3

1.81 1.22 3.34 1.55 1.66 2.89 1.69 0.92 2.72 4.22 1.50 1.09 1.63 1.44 1.09 3.11 3.89 1.34 2.14 3.65 3.28 2.18

CeOi 76 16 64 41 13 55 59 27 27 29 54 61 50 22 14 61 47 85 63 27 62 72

Eu 0 2

3

0.93 0.24 0.55 0.26 0.23 0.28 0.57 0.47 0.17 0.38 0.15 0.31 0.24 0.16 0.19 0.62 0.45 0.44 0.41 0.40 0.57 0.47

Million

HfOt

Th0

3.65 1.87 5.52 2.73 1.98 4.16 2.88 1.41 2.59 3.28 1.36 1.08 2.88 1.19 0.97 4.69 4.07 2.38 3.78 3.18 4.71 3.14

3.60 1.81 3.35 1.85 1.96 3.09 2.93 0.93 2.74 4.01 1.53 1.08 2.01 1.01 1.06 3.89 4.22 2.11 3.62 3.54 3.49 2.86

Cr 0

2

2

0.43 0.29 0.44 0.30 0.24 0.57 0.39 0.25 0.46 0.53 0.16 ND* 0.29 0.15 ND 0.52 0.47 0.52 0.49 0.50 0.55 0.46 6

3

19.0 8.9 27.0 25.2 9.1 31.2 16.1 15.7 20.3 23.1 12.6 9.9 15.0 12.0 649.0 34.6 25.7 16.6 24.1 30.4 35.1 22.5

CoO

Sb 0 2

3

7.02 17.3 13.4 - 1.87 2.15 14.9 6.4 14.50 23.2 4.10 2.08 12.7 4.32 17.7 3.59 37.7 1.30 9.3 10.2 3.80 1.14 11.7 0.99 93.1 1.82 41.8 3.07 5.8 166.0 20.80 3.49 64.8 1.24 8.8 5.56 69.5 53.4 3.11 34.1 1.73 4.70 53.3 4.14 60.3


110

ARCHAEOLOGICAL

Figure 10.

CHEMISTRY

Pieces of grisaille glass from The Cloisters Museum. Analytical are given in Table I.

data

Top: Accession numbers and attributions are 30.73.218: English, ca. 1290; 30.73.212: French or English, end XIII; 30.73.211: French or English, ca. 1300; 30.73.210: French or English, early XIV; 30.73.217: French or English, XIII-XIV; 30.73.216: French or English, ca. 1300; 30.73.214: French or English, end XIH-beginning XIV. Middle: Accession numbers and attributions are 23.229.5-2: French, XII; 23.229.5-5: Paris, XIII; 23.229.5-6: Bourges, XIII; 23.229.5-8: Rheims, XIV; 23.229.5-7: Paris, XIV; 23.229.5-9: Evereux, XIV; 23.229.5-10: Bourges, XIII. Bottom: Accession numbers and attributions are 23.229.2-2: striated red ghss— Chartres, XII or XIII; 23.229.2-14: green glass—Paris, XIII; 23.229.4-7: Bourges, XIII; 23.229.2-3: glashed red glass—Paris, XIII; 23.229.4-1: Rheims, XIV; 23.229.2-10: Angers, XIII; 23.229.4-6: Bourges, XIII; 23.229.4-4: Bourges, XIII.


7.

OLiN

A N D

SAYRE

Neutron

Activation

of Medieval

111

Glass

t o o l to r e m o v e the s u r f a c e h y d r o l y z e d l a y e r . T h e corners w e r e s c r a t c h e d w i t h a c a r b i d - t i p p e d stylus, a n d samples of a b o u t 100 m g e a c h b r o k e n off.

were

T h i s a m o u n t c a n b e t a k e n , a n d the f r a g m e n t c a n b e p l a c e d

i n t o the n e w l e a d i n g w i t h o u t n o t i c e a b l e c h a n g e to t h e p a n e l . T h i s o p p o r t u n i t y to s a m p l e panels d u r i n g r e s t o r a t i o n s h o u l d not b e

overlooked

b e c a u s e o f the s i m p l i c i t y of the p r o c e d u r e at that t i m e . G l a s s s a m p l e s f r o m the a l r e a d y separate glass pieces of the t h i r d g r o u p of

specimens

were removed i n a similar manner. Analytical

Results

M e d i e v a l s t a i n e d glass is g e n e r a l l y u n d e r s t o o d to h a v e b e e n

made

w i t h s a n d , w o o d ash, a n d p e r h a p s l i m e . B e c a u s e the w o o d a s h c o n c e n t r a t i o n of p o t a s s i u m is h i g h r e l a t i v e to that of s o d i u m , one expects a h i g h c o n c e n t r a t i o n of p o t a s s i u m oxide.

A l l b u t f o u r of the

specimens

a n a l y z e d c o n f i r m e d this e x p e c t a t i o n , w i t h p o t a s s i u m o x i d e c o n c e n t r a t i o n s b e t w e e n 11 a n d 3 2 % . oxide 5-20%

concentrations

T h e e x c e p t i o n a l f o u r specimens h a d p o t a s s i u m of

2-5%

and

sodium

oxide

concentrations

a n d c l e a r l y w e r e f o r m u l a t e d w i t h a different a l k a l i .

of

I n fact,

great v a r i a t i o n w a s g e n e r a l l y o b s e r v e d i n the r e l a t i v e concentrations of alkalies i n m e d i e v a l glass, a s i t u a t i o n that contrasts w i t h the r e l a t i v e l y f e w f o r m u l a t i o n s e n c o u n t e r e d i n ancient glass

(7).

T a b l e I lists a n a l y t i c a l d a t a o n specimens

of o u r set of

random

samples ( F i g u r e 10) w h i c h w e r e selected to s h o w the r a n g e of c o m p o s i tions w h i c h c a n c h a r a c t e r i z e m e d i e v a l w i n d o w glass.

B e c a u s e of

the

m a r k e d differences i n the concentrations of t h e constituents s h o w n i n this t a b l e , i t is not l i k e l y t h a t m e d i e v a l glass of u n r e l a t e d o r i g i n s w o u l d b e closely s i m i l a r i n c o m p o s i t i o n . I n contrast to the d i v e r s i t y i n c o m p o s i t i o n s e n c o u n t e r e d i n t h e u n r e l a t e d specimens a b o v e , a l l 45 samples of u n c o l o r e d or a m b e r glass w i t h g r i s a i l l e p a i n t i n g f r o m the C h a t e a u of R o u e n w e r e b a s i c a l l y s i m i l a r i n composition. about 3.5%

T h i s glass contains a b o u t 1 5 % p o t a s s i u m o x i d e a n d o n l y s o d i u m o x i d e (see

Table II).

B e c a u s e these s i m i l a r s p e c i

mens c a m e f r o m the same b u i l d i n g , a c o m m o n source of m a n u f a c t u r e seems l i k e l y .

T h e s e d a t a therefore s u p p o r t o u r b e l i e f that i n d i v i d u a l

sources of glass p r o d u c e d c o m p o s i t i o n a l l y consistent p r o d u c t s . C o n s i d e r the d a t a o n the colorless

glass f r o m the seven

Rouen

C h a t e a u panels, p a n e l b y p a n e l , as s h o w n i n T a b l e I I . W i t h i n t h e s p e c i mens t a k e n f r o m i n d i v i d u a l panels there are groups of fragments w i t h exceptionally similar compositions.

T h i s is not s u r p r i s i n g since a n u m b e r

of fragments p r o b a b l y w e r e p r o d u c e d f r o m a single m a n u f a c t u r i n g b a t c h , a n d the fragments f r o m the same b a t c h w o u l d p r o b a b l y b e u s e d i n the same p a n e l . T h i s seems to b e the most l o g i c a l e x p l a n a t i o n of this e x c e p -


112

ARCHAEOLOGICAL

t i o n a l u n i f o r m i t y a m o n g specimens.

CHEMISTRY

I n T a b l e I I , v e r y closely

matched

specimens are g r o u p e d a n d p r i n t e d i n r o m a n t y p e . I n one p a n e l , 69.236.4, w e e n c o u n t e r e d o n l y specimens w i t h v e r y s i m i l a r compositions.

It w o u l d

be i n t e r e s t i n g to a n a l y z e a l l t h e fragments of this p a n e l to

determine

Table II. Specimen No.

Concentration of Oxides in Percent BaO

MnO

R013\ R014/ R011 R012 R017 ROW ROW

Ivy Panel 4.0 3.9 3.6 2.3 3.9 4.5 2.3

69.286.2 13.0 13.8 16.1 15.7 15.1 12.5 16.5

0.122 0.128 0.115 0.128 0.116 0.083 0.132

1.12 1.12 1.10 1.24 1.01 0.97 1.01

0.59 0.61 0.49 0.49 0.49 0.98 1.66

Colorless

R0191 I > R023 R020' R022 R018 R021 R024

Ivy Panel 3.2 3.5 4.1 4.1 4.1 4.0 4.4

69.236.8 14.9 15.5 16.1 16.0 14.6 12.6 14.5

0.116 0.103 0.126 0.136 0.125 0.118 0.114

1.05 1.13 1.07 1.05 1.16 1.02 1.20

0.49 0.49 0.58 0.57 0.57 0.57 0.56

Colorless

R0281 R029I R030 R031

Ivy Panel 4.2 4.1 4.0 3.9

69.236.4 0.124 15.8 0.110 15.2 0.115 17.7 0.117 13.9

1.17 1.09 1.07 1.08

0.56 0.55 0.55 0.55

Colorless

R011 R02 R03J

Ivy Panel 4.1 4.3 4.5 2.5 3.6 5.0

69.236.6 13.4 14.1 14.3 164 20.6 18.0 13.8 17.0 16.9 18.3

0.122 0.119 0.118 0.137 O.I4O 0.121 0.133 0.131 0.147 0.106

1.12 1.24 1.14 1.00 1.03 1.26 1.09 1.02 1.16 1.12

0.59 0.61 0.61 0.73 0.73 0.58 0.56 0.65 1.66 I43

69.236.7 13.5 12.6 16.3 14.6 15.2 15.3 14.8

0.113 0.107 0.126 0.123 0.133 0.142 0.126

1.06 1.11 1.14 1.15 1.06 1.19 1.34

0.49 0.49 048 0.57 0.55 0.67 Ο45

Colorless

Amber Blue

R04

R05 R06 R09 ROW R07 R08

Amber Blue

Colorless

R0341 R037/ R032 R033 R035 R036 R038

Na 0 2

44

2.8 2.2 2.5 Ivy Panel 3.2 3.5 2.2 4.2

2.4

4.0 2.6

K0 2


Fe 0 2

3

7.

OLiN

AND

SAYRE

Neutron

Activation

of Medieval

113

Glass

w h e t h e r t h e y w e r e f o r m e d f r o m a single b a t c h of glass. I n g e n e r a l , h o w ever, w e h a v e e n c o u n t e r e d e i t h e r m o r e t h a n one e x c e p t i o n a l l y closely m a t c h e d g r o u p or other specimens w h i c h s h o w a h i g h e r o r d e r of differ ence i n c o m p o s i t i o n . Glass from the Rouen Chateau Panels Parts per Rb 0 2

Cs 0 2

Sc O 2

z

Ce0

2

Eu O

Hf0

Million

2

z

2

Th0

2

Cr 0, 2

CoO

Sb 0* 2

322 344 288 225 252 255 141

1.64 1.36 1.37 0.56 0.89 1.05 0.92

2.08 2.22 1.74 1.73 1.81 1.86 2.10

51 61 54 44 83 41 78

Ivy Panel 0.55 0.50 Ο.48 Ο.47 0.38 0.48 O.4I

69.236.2 1.90 2.38 2.05 2.70 1.89 2.77 2.13 3.60 1.86 144 3.96 1.88 5.65 2.79

20.0 18.0 15.6 16.6 16.8 27.0 30.5

28.3 30.0 20.0 20.2 17.0 870.0 1390.0

4.2 4.2 3.5 4^0 0.4 39.4 237.0

331 336 388 383 370 384 341

1.03 1.15 1.16 1.18 1.28 1.17 0.82

1.74 1.70 2.25 2.12 2.12 2.20 2.10

54 55 63 60 61 61 55

Ivy Panel 0.41 0.35 0.62 0.59 0.58 0.52 0.59

69.236.3 2.06 2.31 1.67 2.33 2.13 2.55 2.16 2.45 2.07 2.76 1.92 2.45 1.91 2.73

13.4 15.3 17.9 19.2 18.2 17.1 15.3

17.3 20.9 25.2 24.0 26.0 24.4 25.8

2.9 2.3 3.3 3.1 4.2 2.9 4.3

365 345 353 345

1.24 1.01 1.06 1.29

2.10 2.02 2.09 2.13

58 52 57 55

Ivy Panel 0.50 0.49 0.51 0.56

69.23'6.4 2.32 2.69 1.94 2.40 1.98 2.69 2.10 2.65

13.3 15.5 15.4 20.3

28.3 26.6 27.8 25.6

4.0 3.9 3.7 4.0

322 329 340 198 181 348 210 173 175 75

1.20 1.75 1.28 0.75 0.52 1.67 0.68 0.62 Ο.48

—

2.12 2.75 2.26 2.31 2.15 2.11 1.96 1.90 2.25 1.09

56 53 59 87 79 58 73 77 84 49

Ivy Panel 0.58 0.56 0.61 0.62 0.58 Ο.48 0.48 0.48 0.65 0.51

69.236.6 2.84 1.83 2.06 2.76 1.91 2.45 2.64 3.49 2.53 3.53 1.75 2.58 1.95 2.84 3.15 2.07 5.59 3.43 4.13 1.94

18.6 19.2 18.3 20.0 18.9 15.1 14.9 15.7 22.5 16.1

26.2 29.3 24.7 25.7 45.9 28.6 24-1 16.8 1220.0 890.0

4.2 4.5 3.5 3.7 15.5 3.5 3.2 2.4 177.0 132.0

346 333 228 359 221 207 243

1.26 1.12 0.55 1.08 0.55 0.75 0.53

1.69 1.69 1.62 2.16 1.97 2.04 1.64

34 45 35 45 53 84 40

Ivy Panel 0.49 0.48 0.34 0.61 0.46 0.58 0.39

69.236.7 1.57 2.05 1.67 1.95 1.96 3.68 1.77 2.55 2.28 2.4Ο 2.22 3.17 1.86 2.75

13.3 16.0 14.8 17.6 14.2 16.7 12.6

16.6 18.9 19.5 25.5 25.5 21.3 19.1

3.1 4.6 2.9 4.5 0.3 14 5.8


114

ARCHAEOLOGICAL

CHEMISTRY

Table II. Percent seamen No. Colorless

R039^ ( R043If R0411 1 R045J [

R040 R042 ROU ROlfi

Blue Colorless

R e d flashed Amber Green Blue

R049] R050 R051 R055 R056 R048 R052 R053 R054

NatO Ivy Panel 2.5 2.5 3.1 3.3 2.2 3.9 3.1 2.1

K0

BaO

MnO

Fe 0

69.236.8 17.1 15.0 14.1 15.8 17.2 13.7 14-9 16.9

0.120 0.124 0.101 0.111 0.129 0.121 0.094

1.27 1.25 1.06 1.10 1.15 1.09 1.07 1.08

0.46 0.45 0.51 0.48 0.57 0.55

1.31 1.36 1.32 1.30 1.36 0.98

0.58 0.49 0.49 0.58 0.53 0.48

0.84

O.4I

2

0.145

Acanthus Panel 69.236.10 0.144 15.2 2.7 0.147 2.7 16.1 0.142 16.7 2.6 0.142 2.7 14.8 0.149 16.3 2.7 0.118 16.2 2.5 0.107 15.8 2.4 0.122 15.8 3.0 0.117 1.9 10.7

1.00 0.85

~1 I 1 1 1 MEAN ± STANDARD DEVIATION • 41 CLEAR GLASS SAMPLES * 4 AMBER GLASS SAMPLES • 6 BLUE GLASS SAMPLES

100

50

Hi

Figure 11. Comparison of mean concentrations of major and minor components in colorless, amber, and blue glass in the grisaille panels from the Chateau of Rouen


2

3

Ο.45 1.71

0.60 0.96

7.

OLiN

Neutron Activation

A N D SAYRE

of Medieval

115

Glass

Continued Parts per

Ce0

Rb 0

Cs 0

240 241 329 330 252 300 316 227

0.59 0.59 1.43 1.22 0.82 1.60 1.21

275 284 292 359 326 232 266 279 264

0.92 0.70 1.03 0.87 1.03 0.75 0.83

1.81 1.75 1.81 1.94 1.66 1.54

1.14

1.98 1.77

2

Sc O 2

2

z

0.48

0.47

Hf0

Ivy Panel 0.34 0.45 0.58 0.41 0.39

69.236.8 3.39 1.70 1.73 3.18 1.41 1.86 2.02 1.63 3.15 2.48 1.75 2.35 1.85 1,44 4.02 3.39

14.7 13.1 18.0 16.8 19.8 14.3 12.3 20.4

19.4 18.7 17.6 16.9 20.9 26.4 14.5 1170.0

Acanthus Panel 69.236.10 92 2.15 2.69 0.51 2.14 91 0.50 2.46 2.19 96 0.60 2.39 2.14 0.56 2.66 103 96 2.15 0.40 2.38 2.03 2.38 0.43 84 2.11 75 2.61 0.37 80 0.38 2.54 3.4I 4.76 92 1.59 0.50

14.0 10.0 14.3 15.2 15.2 20.9 14.7 11.5 19.4

42.0 42.1 39.8 45.5 40.4 23.0 14.0 59.4 1300.0

43 39 48 42 65 49 33 96

I.49

2

z

0.46 0.76

Ε—ι—ι—ι—ι—ι—ι—ι—ι—ι

£

100

ι

ι

ι

MEAN*ONE STANDARD DEVIATION • 41 CLEAR GLASS SAMPLES * 4 AMBER GLASS SAMPLES • 6 BLUE GLASS SAMPLES

ζ ο 1000

ι

Cr O 2

2

2

0.49

5000

É

Th0

Eu O

2

1.67 1.61 1.67 1.64 1.99 1.97 1.56 2.12

Million

ι

ο 1 I

5

'·°

ΰ

0.5

ι

Γ

2

Ht

ιο

en

ι

k

• I

ι

CoO

z

IRb0ι 2

ι ι Cs 0 2

ι ι Sc 0 2

3

ι ι Ce0 2

1 ι Eu^

ι ι Hf0 2

ι ι Th0 2

I I Cr 0 2

3

I I 1 CoO 0

Figure 12. Comparison of mean concentrations of trace components in colorless, amber, and blue glass in the grisaille panels from the Chateau of Rouen


Sb O 2

z

6.3 4.4 5.9 2.3 14 3.0 1.6 130.0 1.2 1.7 0.8 1.8 1.9 44 0.3 113.0 43.7

116


Figure 13. Pieces of grisaille glass from The Chisters Museum. Accession numbers and attributions are 23.229.4-8: Paris, XIV; 23.229.4-9: Chartres ?; 23.229.4-11: Chartres, ? XIV; 30.73.208: French, ? XIII-XIV. Analytical data in Table III. I n c o m p a r i n g glass f r o m different panels one o b s e r v e d i n g e n e r a l o n l y a b o u t the same o r d e r of difference

that exists b e t w e e n

different

fragments i n the same p a n e l w h i c h d o not correlate v e r y closely. of those differences

p r o b a b l y represent the n o r m a l v a r i a t i o n

Most

between

batches of glass f r o m the same w o r k s h o p . A c o m p a r i s o n a m o n g the average c o m p o s i t i o n of t h e colorless, the a m b e r , a n d some of the b l u e glasses f r o m the R o u e n C h a t e a u is s h o w n i n F i g u r e s 11 a n d 12. F o r most elements the s t a n d a r d d e v i a t i o n ranges of concentrations e n c o u n t e r e d i n a l l three colors o v e r l a p , a n d hence the a v e r a g e concentrations i n e a c h of the colors w e r e not s i g n i f i c a n t l y d i f Table III.

First Matching Group of Grisaille Fragments

Identified

Percent Accession

No.

23.229.4-8 23.229.4-9 23.229.4-11 30.73.208 Mean G r o u p s t d dev.,

Na 0 2

%

0.33 0.30 0.30 0.30 0.31 4.9

K0

BaO

MnO

18.2 18.2 19.4 17.9 18.4 3.6

2.54 2.19 1.42 2.69 2.15 33.5

1.21 1.16 1.22 1.32 1.23 5.5

2


Fe O 2

z

0.44 0.31 0.41 0.43 0.39 17.6

7.

Neutron

OLIN AND SAYRE

ferent f r o m e a c h other.

Activation

of Medieval

117

Glass

H o w e v e r , i n the b l u e glasses the c o b a l t , i r o n ,

t h o r i u m , a n d c h r o m i u m concentrations w e r e a l l h i g h e r , b u t this c o u l d be a r e s u l t of a c o b a l t - c o n t a i n i n g m a t e r i a l a d d e d as a colorant.

I n a l l the

c o l o r e d glasses, a n d i n the green a n d flashed r e d glasses a n a l y z e d , the same b a s i c glass seems to h a v e b e e n used. T h e r e f o r e , a l l of the a b o v e glass w a s p r o b a b l y p r o d u c e d b y a single w o r k s h o p . T h r e e a d d i t i o n a l pieces of b l u e glass w e r e i d e n t i f i e d as restoration glass o n the basis of t h e i r p h y s i c a l a p p e a r a n c e before s a m p l i n g . S a m p l e s R 0 2 5 , R 0 2 6 , a n d R 0 2 7 w e r e t a k e n f r o m these pieces w h i c h w e r e a l l i n p a n e l 69.236.4 s h o w n i n F i g u r e 4. S a m p l e s R 0 2 5 a n d R 0 2 6 are not s h o w n because the entire top area of that p a n e l w a s r e p l a c e d d u r i n g r e c e n t restoration. F i g u r e 4 shows the r e c e n t l y restored p a n e l . T h e c o n c e n t r a -

Figure 14. GHsaille glass from The Cloisters Museum. The accession numbers and attributions are 23.229.5-4: Chartres, XIV; 30.73.206: French or English, late XIII; 30.73.207: French or English, early XIV; 30.73.209: French or English, beginning XIV; 30.73.213: French, ? XUI-XTV; 30.73.215: French or English, XIV. Analytical data in Table IV. (See Figure 1)

Using Accession Numbers of The Cloisters Museum Parts per Rb 0

Cs 0

Sc 0

Ce0

250 260 260 290 265 6.6

2.0 2.2 2.6 2.4 2.3 12.0

2.29 1.73 2.13 2.28 2.09 14.1

37 0.179 26 0.214 37 0.207 33 0.450 0.244 33 18.1 51.3

2

2

2

3

2

Eu 0 2

3

HfOt 2.8 2.3 2.7 2.9 2.7 10.8

Million Th0

2

3.4 3.4 4.2 3.7 3.7 10.5

Ta 0 2

&

0.36 0.36 0.38 0.38 0.37 3.2

Cr O 2

z

16.5 13.5 16.7 22.7 17.1 23.9

CoO

Sb 0:

9.5 5.7 8.7 11.0 8.5 33.0

1.4 1.6 1.7 0.9 1.3 29.3


2

118


Table I V .

Second Matching Group of Grisaille Fragments

Identified

Percent Accession

No.

23.229.5-4 30.73.206 30.73.207 30.73.209 30.73.213 30.73.215 Mean G r o u p s t d dev., %

Nc^O 2.5 2.7 3.1 2.6 2.6 4.0 2.9 19.5

BaO

MnO

Fe 0

0.135 0.147 0.127 0.141 0.146 0.138 0.139 5.6

1.01 1.23 1.08 1.05 1.03 1.00 1.06 7.9

0.51 0.52 0.51 0.51 0.50 0.53 0.51 2.0

KîO 14.1 14.5 14.9 15.3 13.6 12.5 14.1 7.5

2

3

t i o n of s o d i u m o x i d e r a n g e d f r o m 0.5 to 3 . 2 1 % , a n d t h e c o n c e n t r a t i o n of p o t a s s i u m o x i d e r a n g e d f r o m 5.27 to 8 . 5 5 % .

T h e m a r k e d difference f o r

these t w o oxides b e t w e e n this glass a n d t h e r e m a i n d e r o f t h e R o u e n glass s a m p l e d ( T a b l e I I ) is e v i d e n t . F r o m t h e r a n d o m samples, t w o sets of c o m p o s i t i o n a l l y r e l a t e d glass emerged.

O n e set ( F i g u r e 13) is c l e a r l y s t y l i s t i c a l l y r e l a t e d . T h e d a t a

f o r these f o u r pieces o f glass a r e g i v e n i n T a b l e I I I . T h e s e c o n d set, c o m p o s e d of six c o m p o s i t i o n a l l y m a t c h i n g pieces ( F i g u r e 14 a n d T a b l e IV),

are d i s t i n c t l y different i n c o m p o s i t i o n

from

the group

of four.

F i g u r e s 15 a n d 16 c o m p a r e t h e average o x i d e c o n c e n t r a t i o n a n d s t a n d a r d d e v i a t i o n ranges of t h e i r v a r i a t i o n s f o r these t w o sets of glass. T h e y show

that t h e oxides

of s o d i u m , b a r i u m , c e s i u m , c e r i u m , e u r o p i u m ,

t h o r i u m , a n d c o b a l t are a l l s i g n i f i c a n t l y different i n these t w o groups.

100 p50-

(J

1

1

1

MEAN ± ONE STANDARD DEVIATION . . 6 SAMPLES * 4 SAMPLES

10

I 0.5

0.1

BaO

MnO

Figure 15. Comparison of mean concentrations of major and minor components in two sets of compositionally related pieces of glass from The Cloisters Museum. Specimens shown in Figures 13 and 14.


7.

OLiN

Neutron

A N D SAYRE

Activation

of Medieval

(See Figure 2)

Using Accession Numbers of T h e Cloisters Museum Parts per Rb 0 2

CsiO

Ce0

2

0.62 220 240 0.68 230 0.95 240 0.90 250 0.86 250 0.77 0.79 238 5.1 18.2

1.74 1.70 1.75 1.62 1.67 2.00 1.74 7.6

Eu 0 2

61 82 79 71 66 58 69 14.9

Ί

Th0

2

0.76 0.45 0.51 0.44 0.40 0.52 0.50 25.3

o 500F

Million

Hf0

3

2

3.2 2.8 3.1 2.7 2.7 2.3 2.8 12.5

1

119

Glass

2.1 2.0 2.2 2.4 2.3 2.2 2.2 6.7

1

1

TaiOi 0.31 0.30 0.31 0.31 0.25 0.33 0.30 10.0

1

1

Cr 0 2

3

14.5 16.4 16.8 13.5 16.4 18.5 15.9 11.9

CoO

Sb 0;

61 8 33 48 48 40 42 32.7

5.7 2.1 1.1 3.1 3.3 4.8 2.9 83.1

2

1

MEAN ± ONE STANDARD DEVIATION • 6 SAMPLES * 4 SAMPLES

cr lOOk 50F cr Ι0

Ξ

5Z

o I-

< cr

I

Ξ

0.5

Ξ

0.1

ο

Figure 16. Comparison of mean concentrations of trace com ponents in two sets of compositionally related pieces of glass from The Cloisters Museum. Specimens shown in Figures 13 and 14. T h e m a t c h i n g set o f s i x i n d i v i d u a l glass pieces is closely r e l a t e d compositionalh

to t h e glass o f t h e R o u e n C h a t e a u p a n e l s . F i g u r e s 17

a n d 18 c o m p a r e t h e c o m p o s i t i o n s o f these glasses. O b v i o u s l y t h e y c a n n o t be d i s t i n g u i s h e d o n t h e basis o f t h e elements d e t e r m i n e d . T h u s , these six pieces o f glass w e r e p r o b a b l y p r o d u c e d b y t h e s a m e m a n u f a c t u r e r as the R o u e n C h a t e a u glass. T h e set o f samples f r o m a p a n e l at t h e M u s e u m o f A r t , P r i n c e t o n U n i v e r s i t y ( F i g u r e 9 ) h a v e i n t e r n a l c o m p o s i t i o n a l consistencies w h i c h a l l o w conclusions s i m i l a r t o those f o r R o u e n panels. E l e v e n f r a g m e n t s f r o m this p a n e l w e r e s a m p l e d a n d a n a l y z e d ( T a b l e V ) . P o t a s s i u m o x i d e concentration was about 2 6 % , a n d sodium oxide about 0.5%.

concentration was

T h i s glass is c o m p l e t e l y different i n c o m p o s i t i o n f r o m t h a t


120

ARCHAEOLOGICAL

CHEMISTRY

100 r 50

41 ROUEN S A M P L E S 6 GRISAILLE FRAGMENTS

:

10

1.0

4 *

0.5

0.05

0.01

< 2 Να 0 2

K 0

BaO

2

MnO

Fe 0 2

3

Figure 17. Comparison of mean concentra tions of major and minor components in sam ples from the set of six matching pieces of glass shown in Figure 14 and the samples from the Rouen glass shown in Figures 2-8

Table V .

Grisaille Panel—Collection of the Princeton Percent

Fragment

No.

1 3 4 5 6 7 9 10 Mean G r o u p std dev., % 2 8 11 Mean G r o u p std dev., %

Na 0 2

0.57 0.51 0.55 0.56 0.53 0.54 0.49 0.54 0.54 5.1 0.61 0.62 0.61 0.61 0.9

K0

BaO

MnO

Fe 0

31 25 29 28 28 28 27 29 28 6.4 21 22 21 21 2.9

0.42 0.45 0.46 0.47 0.41 0.44 0.42 0.45 0.44 5.0 0.36 0.33 0.36 0.35 2.2

1.30 1.27 1.23 1.43 1.25 1.23 1.37 1.38 1.31 6.0 0.94 0.86 0.93 0.91 5.0

0.42 0.45 0.45 0.44 0.40 0.42 0.42 0.43 0.43 4.1 0.58 0.53 0.52 0.54 6.0

2


2

7.

OLiN

Neutron

A N D SAYRE

Activation

of Medieval

121

Ghss

of t h e C h a t e a u of R o u e n a n d a l l of t h e s i n g l e pieces o f glass a n a l y z e d . T h i s l a c k of c o r r e l a t i o n demonstrates c l e a r l y t h e d i s t i n c t differences i n c o m p o s i t i o n s o b s e r v e d f o r glasses f r o m different sources. T h i s p a n e l a g a i n shows t h a t t h e c o m p o s i t i o n f o r glass f r o m a single source c a n b e consistent. A l l specimens w e r e so close i n c o m p o s i t i o n t h a t

41 ROUEN SAMPLES 6 GRISAILLE FRAGMENTS

500

100

1

\

4

50

10

. Τ*

Q_ Τ Ο (Τ

S LOI UJ

ι * t ιι τ

τ

0.5 9

m

^

Neutron Activation Analytical Survey of Some Intact Medieval Glass

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