Preliminary Investigations on Chinese Ink in Far Eastern Paintings

11 Preliminary Investigations on Chinese Ink

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in Far Eastern Paintings JOHN WINTER Freer Gallery of Art, Smithsonian Institution, Washington, D.C. 20560 Chinese ink, an intimate mixture of combustion carbon and animal glue, was originally based on pine wood soot, but lampblack from oil lamps became dominant after about the 11th century. Various inks, many from paintings, were studied by scanning electron micrographs; these enable individual carbon particles to be seen and some approximate particle size distributions to be constructed. Combustion carbon can be recognized easily as a pigment in paintings. Lampblack inks seem to have a fairly narrow particle size distribution; pine soot inks give more variable distributions. The reason some inks show a bluish and some a brownish tint is concluded to be light absorption differences by the carbon rather than additives or Tyndall effects. Though falling into the same range, distributions differ sufficiently in shape to suggest that they could be an identifying characteristic in some cases.

V V T r i t i n g a n d the written w o r d have always h a d a special importance in Chinese culture. Paper a n d printing are both Chinese inven tions; t h e h a i r b r u s h , also u s e d f o r w r i t i n g , has a c o n s i d e r a b l e a n t i q u i t y i n that country.

A l t h o u g h b l a c k inks a n d p a i n t s w e r e m a d e i n other

parts of t h e w o r l d , p e r h a p s f r o m a n earlier t i m e ( I ) , i t w a s u n d o u b t e d l y the i m p o r t a n c e of l i t e r a c y a m o n g t h e C h i n e s e t h a t l e d t h e m to p r o d u c e i n k of a q u a l i t y u n m a t c h e d a n y w h e r e outside t h e F a r E a s t . F u r t h e r m o r e , u n l i k e m o s t other parts of t h e w o r l d , this same m a t e r i a l w a s u s e d n o t o n l y f o r w r i t i n g a n d p r i n t i n g , b u t i t b e c a m e almost u b i q u i t o u s i n p a i n t i n g . I n t h e present context there is n o d i s t i n c t i o n , of t h e t y p e f o u n d i n western practice, between i n k a n d paint.

Chinese ink could well be

d e s c r i b e d as b l a c k w a t e r - c o l o r p a i n t ; i t w a s a p p l i e d w i t h a b r u s h a n d u s e d t h e same g l u e v e h i c l e as t h a t u s e d w i t h other p i g m e n t s . 207 In Archaeological Chemistry; Beck, C.; Advances in Chemistry; American Chemical Society: Washington, DC, 1974.

T h e ex-

208

ARCHAEOLOGICAL CHEMISTRY

p e r i m e n t a l results offered

here are d e r i v e d f r o m samples t a k e n f r o m

p a i n t i n g s r a t h e r t h a n f r o m examples of p r i n t i n g or w r i t i n g .

However,

C h i n e s e i n k is a t e r m c o m m o n l y u n d e r s t o o d i n several different

fields,

a n d i t w o u l d b e c o n f u s i n g a n d p e d a n t i c to r e p l a c e i t . F e w C h i n e s e , Japanese, or K o r e a n p a i n t i n g s o n flexible supports d o not use b l a c k i n k to a c o n s i d e r a b l e extent.

M a n y were executed using

o n l y this m e d i u m or w i t h slight a d d i t i o n of color.

The virtual ubiquity


of i n k is u n d o u b t e d l y one factor b e h i n d its i m p o r t a n c e i n the F a r E a s t ; t h i s is s h o w n b y the respect a c c o r d e d

its m a k e r s , b y its t r e a t m e n t i n

C h i n e s e h i s t o r i c a l w r i t i n g , a n d b y the extensive i n k l o r e t h a t exists. T h i s p a p e r describes the p r e l i m i n a r y a n d e x p l o r a t o r y p h a s e of a n i n v e s t i g a t i o n of C h i n e s e i n k i n F a r E a s t e r n p a i n t i n g s — i t s p r o p e r t i e s a n d its v a r i a b i l i t y .

T o clarify w h a t such investigation might achieve,

we

m u s t first look briefly at the h i s t o r y a n d m e t h o d of m a n u f a c t u r e of t h e ink.

N o t e that C h i n e s e i n k has b e e n v a r i o u s l y c a l l e d C h i n a i n k , I n d i a

( o r I n d i a n ) i n k , Japanese i n k , a n d o c c a s i o n a l l y b y its Japanese sumi.

name,

T h e C h i n e s e w o r d , less u s e d , is mo.

History

and

Manufacture

C h i n e s e i n k is essentially a m i x t u r e of soot or l a m p b l a c k w i t h g l u e ; o t h e r constituents m a y b e i n v o l v e d a n d are m e n t i o n e d b e l o w .

T h e estab

l i s h e d m a n u f a c t u r i n g m e t h o d stresses b o t h the c a r e f u l c h o i c e a n d p r e p a r a t i o n of the i n g r e d i e n t s a n d the assidousness

and diligence required

during their compounding. T h e o r i g i n s of C h i n e s e i n k are obscure.

T h e r e are references to the

e a r l y use of a b l a c k v a r n i s h ( 2 ) , a n i d e a that has b e e n d i s p u t e d

(3).

A n e a r l y m a t e r i a l c a l l e d shih mo, or "stone i n k " also crops u p i n C h i n e s e l i t e r a t u r e (2,

4)

a n d m a y h a v e b e e n g r a p h i t e or c o a l .

Archaeological

m a t e r i a l seems to b e sparse a n d scarcely s t u d i e d , a l t h o u g h a n i n v e s t i g a t i o n (5,6)

o n the b l a c k p i g m e n t f o u n d o n a S h a n g oracle b o n e suggests

that i t is carbonaceous

a n d p o s s i b l y b l o o d that has d a r k e n e d w i t h t i m e .

S o m e references exist to p r e - H a n potsherds b e a r i n g b l a c k i n k a p p a r e n t l y a p p l i e d w i t h a b r u s h as a l i q u i d (4,

7).

I n k as w e n o w r e c o g n i z e i t is t r a d i t i o n a l l y b e l i e v e d to date f r o m the W e i d y n a s t y , a n d the first extant d e s c r i p t i o n comes f r o m the 5 t h c e n t u r y A . D . (8).

[Ref. 9 erroneously gives the W e i p e r i o d as "220 à 260

a v a n t J . C . " w h e r e "après J . C . " is c l e a r l y meant. W e i are A . D . 2 2 0 - 2 6 5 . ]

A c c e p t e d dates f o r t h e

A c o n s i d e r a b l e p e r i o d of d e v e l o p m e n t

t h e n seems p r o b a b l e , h o w e v e r .

before

S i n c e t h a t t i m e the C h i n e s e l i t e r a t u r e

o n i n k has b e e n f a i r l y extensive; a d e t a i l e d h a n d b o o k o n i n k m a k i n g i n the 14th c e n t u r y has b e e n t r a n s l a t e d i n t o F r e n c h (9), F r a n k e has r e n d e r e d m a n y texts i n t o G e r m a n (4).

and more recently These

and

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

other

11.

Chinese

WINTER

authors ( 2 , 10-15)

209

Ink

h a v e d e s c r i b e d the h i s t o r y of i n k m a k i n g as d e r i v e d

f r o m the C h i n e s e l i t e r a t u r e . F r o m t h e 5 t h c e n t u r y the m e t h o d f o r m a k i n g i n k r e m a i n e d u n c h a n g e d i n essentials. T h e c a r b o n w a s m a d e i n w a y s w h i c h d i d v a r y , a n d this aspect is d e a l t w i t h i n m o r e d e t a i l b e l o w .

A n i m a l glue

was

p r e p a r e d u s i n g c o l l a g e n f r o m v a r i o u s sources, favorites b e i n g deer a n t l e r a n d skins of v a r i o u s a n i m a l s a l t h o u g h fish g l u e is also m e n t i o n e d . A l l Downloaded by UNIV OF CALIFORNIA SAN DIEGO on December 7, 2015 | http://pubs.acs.org Publication Date: June 1, 1974 | doi: 10.1021/ba-1974-0138.ch011

accounts stress the assiduousness w i t h w h i c h the soot o r l a m p b l a c k ,

finely

s i e v e d before use, a n d the s o l u t i o n of glue s h o u l d b e m i x e d . K n e a d i n g , p o u n d i n g , s t e a m i n g , a n d r o l l i n g are a l l r e c o m m e n d e d ,

usually i n com

b i n a t i o n , a n d are to b e d o n e r e p e t i t i v e l y a n d at l e n g t h to o b t a i n a g o o d product.

It m a y b e i n f e r r e d that p r o p e r l y m a d e i n k w i l l h a v e

divided carbon

(a hydrophobic material) a n d protein glue

(a

finely hydro-

p h i l i c m a t e r i a l ) i n t i m a t e l y m i x e d — a p o i n t w h i c h is of s o m e interest r e g a r d i n g its b e h a v i o r . Besides c a r b o n a n d glue v a r i o u s o t h e r constituents h a v e b e e n q u o t e d as b e i n g i n c o r p o r a t e d b y this or that i n k m a k e r , some of t h e m for obscure reasons.

F r a n k e (4)

states t h a t u p to 1100 are k n o w n ; t h e y i n c l u d e

p e r f u m e s l i k e c a m p h o r a n d m u s k , dyes ( e v i d e n t l y to i m p r o v e the a p p e a r a n c e i n some w a y ) , p l a n t extracts, a n d other m a t e r i a l s , some of w h i c h m a y h a v e i m p r o v e d the c o l l o i d a l b e h a v i o r of the system. W h a t concerns us is the c a r b o n p i g m e n t itself. T h i s has b e e n p r e p a r e d i n different w a y s , a n d the differences h a v e h i s t o r i c a l significance ( 2 , 4).

T h r o u g h T a n g times or later the s t a n d a r d p r e p a r a t i o n w a s the

c o n t r o l l e d b u r n i n g of p i n e w o o d i n l o n g ovens of b a m b o o c o v e r e d w i t h paper.

W o o d c u t i l l u s t r a t i o n s s h o w at least t w o o v e n designs t h a t w e r e

u s e d (4, 13);

some are as l o n g as 100 feet. T h e best soot for i n k m a k i n g

w a s c o l l e c t e d at the e n d remote f r o m the fire; c a r b o n f r o m too close to the fire was c o n s i d e r e d u n s u i t a b l e . T h i s c o l l e c t i o n m e t h o d w o u l d m e a n that t h e soot p r o p e r w a s separated f r o m u n w a n t e d d e b r i s s u c h as

fly-ash,

c h a r r e d fragments, a n d t a r r y p r o d u c t s . Soot p a r t i c l e s m a y also h a v e b e e n f r a c t i o n a t e d , s m a l l e r ones t e n d i n g to get i n t o the better inks.

Woods

other t h a n p i n e w e r e e v i d e n t l y t r i e d b u t f o u n d unsatisfactory, a n d p i n e itself w a s g r a d e d for i n k m a k i n g s u i t a b i l i t y (4).

I n any event, this m e t h o d

of o b t a i n i n g the c a r b o n w a s p r o b a b l y inefficient. A t some t i m e , p e r h a p s a r o u n d the 11th to 12th centuries, t h e p r o d u c t i o n of c a r b o n b y b u r n i n g o i l at a w i c k b e c a m e i m p o r t a n t . A c c o r d i n g to L a u f e r ( 2 ) , a n d e s p e c i a l l y to F r a n k e (4), w i t h the extensive

deforestation

o i l b u r n i n g w a s associated

of C h i n a d u r i n g the first m i l l e n i u m

A . D . ; i t r e s u l t e d i n a shortage of p i n e w o o d as r a w m a t e r i a l , a n d i t c o i n c i d e d w i t h a n i n c r e a s i n g i n k d e m a n d for c l e r i c a l a n d s i m i l a r purposes. I n a n y event l a m p b l a c k p r o d u c t i o n f r o m o i l is p r o b a b l y m o r e t h a n p i n e soot p r o d u c t i o n ( t h o u g h a d m i t t e d l y u s i n g a m o r e


efficient expensive

210


f u e l ) , is easier to c o n t r o l , less v u l n e r a b l e to the elements a n d to h a z a r d s , a n d r e q u i r e s less elaborate e q u i p m e n t .

fire

Conveniently, if arbi

t r a r i l y , w e m a y refer to c a r b o n f r o m w o o d b u r n i n g as soot a n d that f r o m o i l b u r n t i n a l a m p as l a m p b l a c k .

T h e r e l a t i v e q u a n t i t i e s of the t w o

types p r o d u c e d w h e n b o t h w e r e i n use are difficult to j u d g e , a n d the l i t e r a t u r e is c o n f l i c t i n g o n this p o i n t (4, 1 3 ) .

O t h e r fuels for p r o d u c i n g

c a r b o n are m e n t i o n e d f r o m t i m e to t i m e , a m o n g t h e m p e t r o l e u m (4)


p i g s fat (11,

12).

and

T h e i r i m p o r t a n c e is h a r d to assess, b u t most authors

r e g a r d i t as m i n o r . T h e i n k s t i c k also e v o l v e d i n t o a m i n o r art f o r m . M a n y sticks e x h i b i t surface d e c o r a t i o n b a s e d o n v a r i e d m o t i f s (4); i n t o s c u l p t u r e d forms ( 3 ) .

later t h e y w e r e m o l d e d

T h e latter w e r e p r e s u m a b l y m a d e e s p e c i a l l y

for collectors r a t h e r t h a n for use. C h i n e s e i n k w a s m a d e i n K o r e a f r o m a n e a r l y d a t e ; at the b e g i n n i n g of the T a n g p e r i o d that c o u n t r y r e m i t t e d a n a n n u a l t r i b u t e of p i n e soot i n k to the C h i n e s e c o u r t (2).

T h e t e c h n i q u e of m a k i n g i n k seemed to b e

i n t r o d u c e d to J a p a n b y a n e n v o y sent b y the K i n g of K o r e a i n 610 A.D.

(2). A f e w t e c h n i c a l studies o n C h i n e s e i n k h a v e b e e n p u b l i s h e d before.

O n e of the earliest (16)

i n c l u d e d a b r i e f i n v e s t i g a t i o n of e l e c t r o p h o r e t i c

properties w h i c h s h o w e d t h a t i n k p a r t i c l e s e x h i b i t e d a n isoelectric p o i n t b e t w e e n p H 4 a n d 5. of g e l a t i n [ca.

T h i s corresponds w e l l w i t h the isoelectric p o i n t

4.5 (17)

a n d ca. 4w8 ( I S ) ]

a n d shows that the c a r b o n

p a r t i c l e s h a v e a n a d s o r b e d l a y e r of collagenous p r o t e i n f r o m t h e glue that is k n o w n h i s t o r i c a l l y to b e present. c o l l o i d p r o t e c t i n g agent (19), c o l l o i d a l systems are e x p e c t e d

G e l a t i n or g l u e is a n efficient

a n d the properties of i n k suspensions as to be those i n v o l v i n g particles w i t h a

p r o t e i n surface r a t h e r t h a n a c a r b o n surface. T w o other papers h a v e s t u d i e d i n k f r o m the p o i n t of v i e w of its colloidal properties: suminagashi

(20)

o n inkstones (21). papers (23, 24) case (23),

one

with

s p e c i a l reference

to

the t e c h n i q u e

of

a n d one w i t h reference to its d i s p e r s i o n b y r u b b i n g A C h i n e s e p a p e r gives some g e n e r a l d a t a (22).

Two

s h o w e l e c t r o n m i c r o g r a p h s of i n k p a r t i c l e s w i t h , i n one

o b s e r v a t i o n o n the tint a n d the o r i g i n of the c a r b o n

(see

b e l o w ). A b o o k p r i m a r i l y o n inkstones also treats i n k i n some d e s c r i p t i v e detail

(25).

Experimental T h e results p r e s e n t e d here are b a s e d o n s c a n n i n g e l e c t r o n m i c r o g r a p h s ( S E M ) of p a p e r fibers c o a t e d w i t h i n k . T h e i n s t r u m e n t u s e d w a s the Stereoscan M a r k I I A ( C a m b r i d g e I n s t r u m e n t C o . , L t d . ) , o w n e d b y the N a t i o n a l M u s e u m of N a t u r a l H i s t o r y . A s a m p l e consisted of a single fiber excised f r o m a n i n k - c o a t e d area of p a p e r ( u s u a l l y a p a i n t i n g )



11.

Chinese

WINTER

211

Ink

a n d m o u n t e d o n a 1 2 - m m c i r c u l a r glass c o v e r s l i p b y s e c u r i n g one e n d w i t h p o l y ( v i n y l acetate) e m u l s i o n . T h e s l i p w a s t h e n s t u c k to a n a l u m i n u m stub a n d c o a t e d w i t h 2 0 - 3 0 n m of g o l d before s c a n n i n g . T h e p a i n t i n g s s a m p l e d are l i s t e d i n T a b l e I. I n a d d i t i o n , t w o m o d e r n i n k sticks w e r e u s e d . O n e ( d e s i g n a t e d m o d e r n l a m p b l a c k i n k ) was a stick k i n d l y g i v e n to t h e F r e e r G a l l e r y b y the K o b a i e n I n k W o r k s i n K y o t o a n d k n o w n to h a v e b e e n b a s e d o n l a m p b l a c k f r o m vegetable o i l l a m p s . T h e other ( m o d e r n b l u i s h i n k ) w a s p u r c h a s e d c o m m e r c i a l l y ( A i k o ' s A r t M a t e r i a l s I m p o r t , C h i c a g o ) a n d , a c c o r d i n g to a leaflet s u p p l i e d w i t h i t , was m a d e f r o m p i n e soot. T h e s e t w o inks w e r e r u b b e d u p w i t h w a t e r , d a u b e d o n to Kdsho ( a n a b s o r b e n t Japanese p a p e r ) , a n d the d a u b s w e r e s a m p l e d as for a p a i n t i n g . T h e r e m a i n i n g s a m p l e w a s of h o u s e h o l d c h i m n e y soot, generated b y a w o o d - f u e l e d fire, w h i c h w a s m u l l e d w i t h g e l a t i n s o l u t i o n a n d spotted o n to the c o v e r s l i p . Table I . Figure No.

Paintings in the Freer Collection Sampled for Scanning Electron Microscopy

Artist

Country,

Period

6 7

Tsou Fu-lei

C h i n a , 14th cent.

9

Wang H u i

China, 17th18th cent. C h i n a , 17th cent. C h i n a , dated 1706 Japan,13th14th cent. K o r e a , 18th cent.

10

K u n g Hsien

11

Wang Yuanch'i Fujiwara Nobuzane (attrib.) Chông S o n (attrib.)

12

13

Subject

Accession No.

p l u m branches i n flower (makimono)

31.1

landscape (makimono) w i n t e r landscape

50.19 61.11

r i v e r landscape

62.5

portrait M i n a m o t o no K i n t a d a

50.25

landscape ( a l b u m leaf)

60.9

T h e p a r t i c l e size d i s t r i b u t i o n s ( F i g u r e s 1-5) w e r e g e n e r a t e d as f o l l o w s . A contact p r i n t of a 4 X 5 i n c h S E M negative at a m a g n i f i c a t i o n of 1 0 w a s c o v e r e d w i t h a transparent p l a s t i c sheet, r u l e d w i t h a g r i d of 1-cm squares. E a c h square w a s e x a m i n e d u s i n g a 6 X m a g n i f i e r h a v i n g a reticle engraved w i t h a 1-cm particle measuring grid. T h e diameter of e a c h i d e n t i f i a b l e single c a r b o n p a r t i c l e w a s e s t i m a t e d to the nearest 0.01 c m a n d r e a d i n t o a tape recorder. L a t e r the tape was p l a y e d b a c k a n d t r a n s c r i b e d . A t 1 0 X , the diameters o n the m i c r o g r a p h i n c e n t i meters are e q u i v a l e n t to a c t u a l diameters i n m i c r o m e t e r s . F o r p l o t t i n g , the diameters w e r e g r o u p e d i n p a i r s (i.e., 0.05 + 0.06 μτη, 0.07 + 0.08 μτη, e t c . ) , a n d the n u m b e r s w e r e n o r m a l i z e d to a t o t a l of 100 p a r t i c l e s . T h o s e of d i a m e t e r less t h a n 0.05 μπι w e r e g r o u p e d a n d p l o t t e d as a combined group. 4

2

4

I n a l l of t h e plots except one ( F i g u r e 1 ) , analyses of at least t w o m i c r o g r a p h s o n samples f r o m the same p a i n t i n g or i n k are c o m b i n e d . T h e l o w e r ( t o p of t h e s h a d e d a r e a ) a n d u p p e r ( t o p of the o p e n


area)


212


10 D I A M E T E R

Figure 1.

15 ( Jim

WP χ

ι 100

Particle size distribution; modern ink. Plotted from one analysis.

)

lampblack

l i m i t s d r a w n for e a c h class of p a r t i c l e diameters represent r e s p e c t i v e l y the least a n d greatest n u m b e r s of p a r t i c l e s i n that class ( as percentages ) that w e r e f o u n d .

T h u s the plots g i v e some i d e a of the v a r i a t i o n over

different d e t e r m i n a t i o n s as w e l l as of the o v e r a l l shape of t h e d i s t r i b u t i o n . E x p e r i m e n t s o n the m o d e r n b l u i s h - t i n g e d i n k i n c o n n e c t i o n

with

t h e d i s c u s s i o n o n i n k tints w e r e as f o l l o w s : ( a ) P o w d e r e d i n k (0.11 g r a m ) w a s Soxhlet e x t r a c t e d successively w i t h acetone ( 4 h r s ) , 2 - p r o p a n o l ( 2 h r s ) , a n d p y r i d i n e (6^ h r s ) . N o c o l o r e d m a t e r i a l was extracted. ( b ) I g n i t i o n of i n k i n a i r to constant w e i g h t : ash r e s i d u e , 1.5%. S e m i q u a n t i t a t i v e analysis of a s h b y e m i s s i o n s p e c t r o g r a p h y gave the f o l l o w i n g elements i n c o n c e n t r a t i o n > 1 % : A l , C a , F e , S i . I g n i t i o n of a t y p i c a l m o d e r n b r o w n i s h - t i n g e d i n k gave a n ash ( 0 . 8 % ), s i m i l a r analysis of w h i c h s h o w e d the same f o u r elements i n c o n c e n t r a t i o n > 1 % .


11.

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WINTER

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Ink

Results Precision and A c c u r a c y . T h i s p r e l i m i n a r y stage w a s d o n e to estimate the w a y s i n w h i c h p a r t i c l e size d i s t r i b u t i o n s v a r y a n d to see h o w

far

t h e y c a n b e u t i l i z e d i n p r a c t i c a l w a y s . T h e a b o v e t e c h n i q u e w a s chosen to e n a b l e us to o b t a i n some a p p r o x i m a t e results c o n v e n i e n t l y , w i t h o u t elaborate s a m p l e p r e p a r a t i o n . T h e s c a n n i n g e l e c t r o n m i c r o g r a p h s


ures 6 - 1 5 )

(Fig

s h o w t h a t too great a n a c c u r a c y s h o u l d not b e e x p e c t e d

at

this stage, e s p e c i a l l y i n v i e w of the i l l - d i s p e r s e d n a t u r e of the p a r t i c l e s i n some cases ( F i g u r e s 7 a n d 1 0 ) .

30r-

5

10

15 DIAMETER

Figure

2.

20

25

Particle size distribution; modern bluish-tinged pine soot. Plotted from two analyses.

The instruments resolving power

30

( μπι χ 1 0 0 )

ink from

is specified to b e 0.025 μτη

or

better. T h i s l i m i t a t i o n alone d i c t a t e d the g r o u p i n g of p a r t i c l e s i n ranges of 0.02 μΐη before p l o t t i n g . R e p r o d u c i b i l i t y of the instrument's m a g n i f i c a t i o n factor was w i t h i n ± 5 % .

A s l i g h t systematic bias t o w a r d s l a r g e r

diameters m a y be present b e c a u s e of the g o l d c o a t i n g o n t h e samples, b u t it s h o u l d be a b o u t constant over this series. T h e greatest sources of error c o m e f r o m t h e difficulties i n e s t i m a t i n g diameters a c c u r a t e l y i n these m i c r o g r a p h s .

T h e y include: misjudgement


214

ARCHAEOLOGICAL

CHEMISTRY


s o h

DIAMETER

(μΐη

χ

100)

Figure 3. Particle size distribution; 14th century Chinese painting No. 31.1. Plotted from five analyses. of a c l u m p of particles as one single one; u n d e r e s t i m a t i o n of the d i a m e t e r b e c a u s e of p a r t i a l e m b e d d i n g of a p a r t i c l e i n g l u e or i n a c l u m p ; selective h i d i n g of p a r t i c l e s b y others easily t h a n large o n e s ) .

( s m a l l e r particles m a y be h i d d e n

I n a d d i t i o n , i t is difficult to a v o i d a

more

subjective


11.

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Chinese

215

Ink


30r-

DIAMETER

Figure 4.

x

100)

Particle size distribution; 14th century Japanese No. 50.25. Plotted from three analyses.

painting

selection factor; the operator m u s t c o n t i n u a l l y d e c i d e w h e t h e r or n o t a p a r t i c l e is m e a s u r a b l e a n d m u s t d o so w i t h o u t b i a s i n g t h e selection for or against a p a r t i c u l a r size. T h e r e p r o d u c i b i l i t y of the d i s t r i b u t i o n w a s c h e c k e d s t a t i s t i c a l l y i n several cases—e.g., the C h i n e s e p a i n t i n g 31.1 ( F i g u r e s 3, 6, 7, a n d 8 ) . F i v e m i c r o g r a p h s f r o m three samples

( t h r e e w e r e f r o m one

sample)

w e r e a n a l y z e d . A l l gave the same k i n d of d i s t r i b u t i o n — a s t r o n g peak i n t h e 0.05 + ameter

0.06 μΐη class, f a l l i n g r a p i d l y to zero w i t h i n c r e a s i n g d i

(Figure 3).

(Figures 6-8)

T h i s is v i s u a l l y c o n f i r m e d

by

the

micrographs

w h i c h s h o w m a n y s m a l l c a r b o n particles a n d v i r t u a l l y

n o l a r g e r ones. C o m p a r i s o n of the plots i n pairs b y a c o n v e n t i o n a l χ s h o w e d v a r i a b l e results, r a n g i n g f r o m no significant difference

2

test

to s i g

nificance at the 0 . 1 % l e v e l . W h e r e the difference w a s significant, i t w a s c a u s e d m a i n l y b y shifts of particles b e t w e e n

adjacent size

n a t u r a l result of i n a c c u r a c y i n the d i a m e t e r measurement.

classes—a

S i m i l a r checks

o n other samples c o n f i r m e d this i m p r e s s i o n . F i g u r e s 6 a n d 7 s h o w d i f ferent degrees of p a r t i c l e m a t t i n g , l e a d i n g to possible

bias as

noted

above. Results f r o m these t w o m i c r o g r a p h s , w h i c h w e r e f r o m the same s a m p l e , w e r e s i g n i f i c a n t l y different. A l t h o u g h the gross features of these


216


p a r t i c l e size d i s t r i b u t i o n s m a y be

t r u s t e d , the present ones are

too

i n a c c u r a t e for close statistical analysis. Discussion General Features of Chinese Ink. F i g u r e s 6 to 13 s h o w a r e p r e s e n t a t i v e selection of s c a n n i n g e l e c t r o n m i c r o g r a p h s of inks f o u n d i n o r i e n t a l


p a i n t i n g s . T h e c a r b o n p a r t i c l e s are s p h e r i c a l a n d h a v e d i a m e t e r s u p to a b o u t 0.20

CO

W

μτη.

20-

υ

I'l

Figure 5.

ι • 30

Particle size distribution; 18th century Korean painting 60.9. Plotted from four analyses.

A c c o r d i n g to the l i t e r a t u r e (26,

27),

No.

soot f r o m d i f f u s i o n

flames

contains s p h e r i c a l c a r b o n p a r t i c l e s f r o m 0.01 to a b o u t 0.20 μτη i n d i a m eter.

T h e structure of s u c h a flame shows a n u m b e r of zones; i n the

i n n e r zones c a r b o n is f o r m e d f r o m gaseous f u e l m o l e c u l e s ; the

outer

ones see the subsequent c o m b u s t i o n of the p a r t i c l e s . W h e r e the latter process is i n c o m p l e t e , the flame p r o d u c e s soot. W e w i l l c a l l s u c h m a terial combustion

carbon

to d i s t i n g u i s h it f r o m t h a t d e r i v e d b y

p y r o l y s i s of existing s o l i d , i n v o l a t i l e f r a g m e n t s , w h i c h w e c a l l char.

the A

c h a r consists of i r r e g u l a r p a r t i c l e s of v a r i o u s sizes, some of w h i c h m a y



11.

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WINTER

217

Ink

Figure 6. Scanning electron micrograph; ink on paper fiber from 14th century Chinese painting No. 31.1


reflect the m o r p h o l o g y of the b u r n t m a t e r i a l . F i g u r e 16 shows a p a r t i c l e of h o u s e h o l d c h i m n e y soot w h i c h is itself a c h a r r e d f r a g m e n t h a v i n g combustion

particles a t t a c h e d to, a n d p a r t l y f u s e d

i n t o , the

surface.

A l t h o u g h chars are possible i n soot i n k s , the d e s i g n of soot ovens ensures c o n s i d e r a b l e f r a c t i o n a t i o n of the c a r b o n , o n l y that w h i c h settles least r a p i d l y b e i n g used. T h i s d i s c r i m i n a t e s h e a v i l y against chars, a n d no s u c h m a t e r i a l has yet b e e n p o s i t i v e l y i d e n t i f i e d i n p a i n t i n g s . T h e particles i n o u r samples are c e r t a i n l y of c o m b u s t i o n

carbon.

T h e y m a y be w e l l d i s p e r s e d ( F i g u r e 1 1 ) , p a r t i a l l y c l u m p e d or m a t t e d b y the glue m e d i u m ( F i g u r e 9 ), or h e a v i l y m a t t e d b y the m e d i u m ( F i g ure 10).

N o association of this last feature w i t h schools or p e r i o d s

of

p a i n t i n g has been detected, except t h a t p a i n t i n g s o n silk u s u a l l y have m o r e h e a v i l y aggregated i n k t h a n those o n paper. I n d e e d , the p r e c e d i n g three examples Chinese).

were

a l l f r o m closely r e l a t e d p a i n t i n g s

(17th-18th

century

T h e definite i d e n t i f i c a t i o n of c a r b o n ( i n p a r t i c u l a r of soot or

l a m p b l a c k ) as a p i g m e n t has p o s e d p r o b l e m s w h e r e o n l y a s m a l l s a m p l e c a n b e t a k e n , a n d the s c a n n i n g e l e c t r o n m i c r o s c o p e m a y be the i n s t r u m e n t of c h o i c e i n m a k i n g s u c h i d e n t i f i c a t i o n . Carbon Manufacture.

T h e h i s t o r y of C h i n e s e i n k i n d i c a t e s that t h e

c a r b o n was m a d e i n at least t w o w a y s — v i z . , b y b u r n i n g w o o d , u s u a l l y p i n e , or b y b u r n i n g o i l . H o w e v e r , other fuels m a y also h a v e b e e n used.


218


I t is h e l p f u l to k n o w i f the m o d e of m a n u f a c t u r e c a n be d i s t i n g u i s h e d for a g i v e n sample. D e s p i t e the a b s e n c e of c h a r n o t e d a b o v e , i t w o u l d b e s u r p r i s i n g i f there w e r e not some reflection of the m e t h o d of m a n u f a c t u r e i n the p a r t i c l e size d i s t r i b u t i o n . A n o i l l a m p has a steady flame of f a i r l y c o n stant size, w h i l e a w o o d fire has a v a r i a b l e , f l i c k e r i n g

flame.

A naive,

i n t u i t i v e v i e w w o u l d be t h a t the w o o d fire c a n be e x p e c t e d to p r o d u c e a Downloaded by UNIV OF CALIFORNIA SAN DIEGO on December 7, 2015 | http://pubs.acs.org Publication Date: June 1, 1974 | doi: 10.1021/ba-1974-0138.ch011

b r o a d e r r a n g e of p a r t i c l e sizes, w h a t e v e r the m e a n a n d m o d e of d i s t r i b u t i o n m i g h t be.

T h e c o n s t a n t l y c h a n g i n g geometry of the

w i l l t e n d to a l l o w some particles to escape before t h e y have

the flame

combusted

v e r y far, others p e r h a p s b e f o r e t h e y are f u l l y f o r m e d .


Figure 9. Scanning electron micrograph; ink on paper fiber from 17th18th century Chinese painting No. 50.19

T o some extent this v i e w is b o r n e out b y o b s e r v a t i o n .

A

modern

i n k k n o w n to h a v e b e e n m a d e f r o m l a m p b l a c k ( F i g u r e s 1 a n d 14)

has

a f a i r l y u n i f o r m p a r t i c l e size, w i t h a strong p e a k to the d i s t r i b u t i o n . F i g u r e s 2 a n d 15 c a m e f r o m another m o d e r n i n k m a d e

(according

to

details that c a m e w i t h i t ) f r o m p i n e soot p r e p a r e d i n the t r a d i t i o n a l way.

Despite

inaccuracies

i n the plots

noted

a b o v e , the

difference

b e t w e e n t h e m is l a r g e e n o u g h to afford some c o n f i r m a t i o n of


expecta-


11.

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WINTER

219

Ink

Figure 10. Scanning electron micrograph; ink on paper fiber from 17th century Chinese painting No. 61.11 tions, e s p e c i a l l y since i t accords


w i t h the v i s u a l i m p r e s s i o n g i v e n

by

F i g u r e s 14 a n d 15. T h e c h i m n e y soot s a m p l e ( F i g u r e 16) offers c o n f i r m a t o r y

evidence.

A l t h o u g h the c o m b u s t i o n p a r t i c l e s are too i l l - d e f i n e d to p e r m i t a w o r t h w h i l e p a r t i c l e size p l o t , a r o u g h analysis suggested a p a r t i c u l a r l y w i d e range of d i a m e t e r s , w i d e r p e r h a p s t h a n those e n c o u n t e r e d i n inks. A n o t h e r i n t e r e s t i n g case is that of the 14th c e n t u r y C h i n e s e p a i n t i n g N o . 31.1. T h e b l u i s h tint of this i n k suggests that i t m a y b e of the p i n e soot t y p e (see

below).

T h e d i s t r i b u t i o n ( F i g u r e s 3, 6, 7, a n d 8 ) is n a r

r o w , b u t i t falls i n a range of c o n s i d e r a b l y s m a l l e r diameters t h a n l a m p b l a c k i n k . T h e p l o t t e d d i s t r i b u t i o n is almost c e r t a i n l y t r u n c a t e d — t h e m e t h o d u s e d d i s c r i m i n a t e d h e a v i l y against p a r t i c l e sizes i n the

Preliminary Investigations on Chinese Ink in Far Eastern Paintings

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