An Examination of Thomas Bardwell's Portraits the Media

8/18/2019 An Examination of Thomas Bardwell's Portraits the Media

1/6

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An Examination of Thomas Bardwell's Portraits: The MediaAuthor(s): R. WhiteSource: Studies in Conservation, Vol. 20, No. 2 (May, 1975), pp. 109-113Published by: on behalf of theManey Publishing International Institute for Conservation ofHistoric and Artistic WorksStable URL: http://www.jstor.org/stable/1505686Accessed: 23-01-2016 16:30 UTC

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2/6

Studies n

Conservation,

0

1975),

109-113

109

AN

EXAMINATION OF

THOMAS

BARDWELL'S

PORTRAITS-THE MEDIA

R.

WHITE

Abstract-Usingas

iquid hromatography,

il-media

nalyses

ere arriedut n a

series

of

portraits

y

Thomas

ardwell.esults

ere

ompared

ith is

wn reatise

hich

evotes

a

section

othe

rinding

f

pigments.

ome

measure

f

greement

as

ound.

1.

INTRODUCTION

This exercise

was

seen

as an

excellent hance

to

attempt

correlation

f

results,

btained

by

experimental

rocedures

sed

in

this

aboratory,

withthose to be

expected

rom n

inspection f Bardwell's reatise1]. Summarizedn Table 1 are theoil-pigmentystems

recommended

or

he

principal

olours,

n

pages

seven nd

eight

f ThePractice

fPainting

and

Perspective.

However,

t is well to

remember

hat,

hough

he

suggests igments

houldbe

ground

with

specified

ils,

neverthelesshe

ground

igmentsmay

well be thinnedwith

drying

il. Bard-

well

gives

us no

precise

nformation

s to what

s

to be understood

y

this erm.

n

most

cases,

reference

o

linseed

oil with

lead drier

s

presumed.

ut there re

recipes

which

describe

he

preparation

f

drying

il

from nut

oil.

What Bardwellmost

probably

meant

by drying

il'

is

best

explained y

Robert

Dossie

who states

n his

Handmaid

o the

Arts,

1758, ,

147-148,

Drying

il is

formed

f

inseed

il,

prepared y

means

of

boiling,

ome-

times

with

he

ddition f other

ubstances,

nd sometimes

ithout. he

substances

dded

to oil, n thispreparation,revery arious: .. white itriol,ugarof ead,seed ac, gum

mastic,

um

andarac,

um

nimi,

um opal,

umber,

olcothar,

itharge,

nd

red ead.'

[2]

Furthermore,

is

text

s

couched n such

terms

s

not to

preclude

he

possibility

hat

he

TABLE 1

OIL-PIGMENT SYSTEMS RECOMMENDED

BY BARDWELL

Flake-white

Poppy-seed

il

Ultramarine

Light chre

Prussian lue

Walnut il

Light

ed

Carmine

Ivory-black

Lake

Indian ed

LinseedOil

Vermilion

Brown-pink

[Prussian lue]

[Light

chre]

[

]

pigments

orwhich nother

il s

thought

ore

uited.

5


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3/6

110

R. White

TABLE

2

SAMPLES FROM

PORTRAITS

BY THOMAS

BARDWELL PRESENTED

FOR

MEDIUM ANALYSIS

Pigment P/S Ratio Oil

Portrait

f

WilliamCrowe

1746)

Al

Greyish-white

f

stocking

Flake

white

3.62

Poppy-seed

Ivory

lack

A2

Scarlet

f

coat,

mid-tone

Vermilion

2.84

Walnut

A3

Blue-grey

ky

Prussian

lue

+

?

1.82

Linseed

(b)

A4

Green

f

drapery,

rowe's ent

Prussian lue

+

3-95

Poppy-seed

b)

King's

yellow

Portrait

f

James

oole

(c.

1765)

B1

White

mpasto,

ace ruff

Flakewhite 2-70 Walnut

(c)

B2 Scarlet fcoat,mid-tone Vermilion 1.51 Linseed

B3

Green

f

drapery,

id-tone

Prussian lue

+

1.66

Linseed

(c)

King's

yellow

Portrait

f

John

Gay

c.

1755)

C1

White

mpasto,

uff

Flakewhite

4-19

Poppy-seed

C2 Scarlet f

coat,

mid-tone

Vermilion

2-71

Walnut

Portrait

f

John

Dersley

1766)

D1

White

ace,

uff f

right

and

Flake

white 3-20 Walnut

Portrait

f

James

hipps

1749)

El Brown ackground,pper ight Umber 2.40 Walnut (a) (b)

Key:

(a)

=

very

mall

ample;

b)

=

area r

edge rotectedy rame;

c)

=

unusual

eaks

resent

n

chromatogram.

may

have

been accustomed

o

purchase

eady-ground

igments.

is

sources

f

supply

may

well have been

unreliable

n

following

is

precise

nstructions

n such matters.

The

analysis

was undertaken ith

hese

pointsfirmly

n mind. Further eference

ill

be

made to these n thediscussion nd conclusion.

he

essential esults re

shown

n

Table

2,

with he dentificationf the oils used byBardwell

n

the ast column.

The

remainder

f

thisarticle s devoted o chemicaldetails and to somediscussion n the reliance o be

placed

on the dentifications.

2. EXPERIMENTAL

Series

Al

to

C2

(Table

2)

weretaken

from

selection f Bardwell's

ortraits,

llustrating

some

ighteenth-century

heriffs

t

Norwich.Miss

Joyce

lesters,

ho

removed

he

amples,

emphasized

hat all were taken as

surface

crapings,

ubsequent

o

the

removal-by

mechanical

means-of

brittle,

iscoloured

varnish.The

latter,

t was

concluded,

was

probably

mastic arnish f

thenineteenth

entury.

ence the

paint

amples

were

bound to

containresidual races f

resin

omponents.

It waspossible o examine nly nesamplefrom portraitf JohnDersley1766),and one

very

mall

ample

of brown

background

rom

portrait

f

James

hipps

1749).

Studies

n

Conservation,

0

1975),

09-113




4/6

An

examination

f

Thomas

ardwell's

ortraits-the

edia

111

Only

a

brief utline f the

experimental

etails

s

given,

ince the

methods

mployed

re

fully

ecorded

n

the

iterature

3, 4].

The

fatty

cid

constituents

f

the

oils

present

werereleased

by overnight

aponification

n

methanolic

otassiumhydroxide,

ollowed

by

acidification. he

organics

were

extracted

withdiethylther, nd derivatives ereprepared ymethylation ithdiazomethane as.

An

estimate

f the relative

roportions

f the volatile

sters

roduced

was

accomplished

by

the

technique

f

gas

liquid

chromatography.

In

the

case

of

samples

Al

to

C2,

distribution

as

carried ut on

a 3

Apiezon

L

(80-100

mesh Diatomite

CQ

support),

ft column.

Those

samples designated

l

and

El

were

examined

on

a similar

olumn,

oaded with

0

OV-1

silicone

gum.

In

each

case,

one-

microlitre

liquots

of the

esterified aterialswere

njected

er

run.

The relative atio

of

palmitic

o stearic sters

was

estimated rom

he

peak

areas

by

cutting

out the

profile

nd

weighing.

wo or three uch estimates

were made

and

the

average

recorded.

hough

different

iquid phase

has

been

employed

or ome of

the

amples,

his

makes

no material ifference

o the

range

of

palmitate/stearate

atios ncountered or

he

various

ypes

f

oil.

Table

3

presents

he

results

o

far.

3. DISCUSSION

AND

CONCLUSION

At this

point,

t s

probably

worthwhile o reiterate

he

principles

nvolved

n

the

technique

and,

in

particular,

o consider

ts

scope

and

limitations.

asically,

he method

eeks

to

distinguish

etween

he

main

types

f oil

commonly mployed

n

paintings, y

measure-

ment

of the relative

roportions

f the two

fatty cids-palmitic

and

stearic.These are

bound

within

rying

il

molecules.

J.

S. Mills

[3],

who conceived

nd

developed

he

technique,

as

already

demonstrated

difference

n

the

palmitate/stearate

atios of fresh

inseed,

poppy-seed

nd

walnut oils.

Moreover,

he has

argued

from heoretical onsiderationshatthe relative

roportions

f

these

omponents

ould be

expected

o remain

easonably

onstant

hroughout

he

drying

and

ageing

process.

Certainly,

ithin

he

domain

of

aboratory-aged

amples,

his

ppears

to be

the case.

Following

an examination

y

Mills and

White

4]

of

a

series

of

paint

specimens

rom

paintings

f the

talian,

North

European,

Spanish

and French

Schools,

t

is

possible

to

prepare

table of

ester atiosfor he

main

oil

types.

The

table

s

merely guide

of

an

empirical

ature,

nd

the occurrence f

a

ratio within

one of

thethree

anges

s

a

strong

ut

not

completely

ertain

ointer

o its

dentity.nspec-

tion

of

Table

3

suggests

n

intrinsicallyreater ertainty

f

dentification

rom hose

ratios

at the

extremes f

the whole

range

han

from hose

n

the

middle.The

latter ould

clearly

arise

from

mixing

f oils

as

well

as

from

walnut.

Uncertainty ust lso arise whenthe ratios re close to the nter-oil oundaries. uch a

TABLE 3

Drying

Oil

[Palmitate/Stearate]

Ratio

Linseed

1-1-2-1

Walnut

2-3-3-4

Poppy-seed 3-6-5-3

Studies

n

Conservation,

0

(1975),

109-113




5/6

112

R.

White

case is

well llustrated

y

the

sample

Al

(William

Crowe

1746).

Here,

the ratio of 3-62 s

clearly

t the ower imit f

a

poppy

oil.

Though

omewhat

igh

or

walnut

il,

t could

well

represent

dmixture f

poppy

and

walnut,

r

linseedoils. The

latter atios

re

lower

nd

so

wouldtend o reduce heoverall

igure.

his

sample

was from

greyish

hite

rea

of

the

picture nd so consists fmixedpigments, robablyvory lackand flakewhite.Table 1

would ead one to

anticipate

oppy

oil

with he

white,

while

walnut il would

have been

used for

grinding

he black.

Sample

Dl

(John

Dersley

1766)

was

found

o be

fairly igh

n

the

walnut

il

range,

nd

a

proportion

f

poppy

oil cannot

be

ruledout.

A

white

mpasto, ample

C1

(John

Gay,

c.

1755),

produced

n

ester atio

of

4-19 nd

may

be ascribedwith easonable

ertainty

o

poppy-seed

il.

It

is

interesting

o note thatBardwell alls attention

o

the

poor

quality

f the

poppy

oil

currently

vailable at the time f

writing

is thesis.He remarks:At

present

ur White

s

bad,

on account fthe

Oil,

which

s

not

really

oppy.'

1]

n

what

espect

his

il

s

deficient,

he

does not indicate.

Poppy

oil

is

noted for ts somewhat

igher

efractive

ndex,

rans-

parency,ack ofcolourwhen resh,nd owyellowingnageing. hus t would eem deally

suited

oruse with

white

igment.

his use of

poppy-seed

il merits

pecial

ttention,

or

n

the

experience

f this

aboratory

t

has

neverbeen

encountered,

xcept

n

paintings

f the

French

chool,

and

apart

from ne instance

nly

n the

previous

nd

present

enturies.

In one case at

least,

inseed il

was

found n

an

area

of

vermilion.

n theother wo

samples,

walnut

il seems o have been used.

Areas of

green,

akenfrom

wo

portraits

A4 [William

rowe,

1746]

nd B3

[James

oole,

c.

1765]),

eem to

vary

n medium.

he earlier eemed o

be

in

poppy-seed

nd

the

ater

portrait

1765),

n

linseed il.

A

sample

fbrown

ackground

rom

ames

hipps

1749)

was

very

mall nd

must

ertainly

represent

lower imit

or he

method.

he

ratio

uggests

he use of walnut il.

Fromtheopening emarksntheexperimentalection,t willbe recalled hat hesamples

were

xpected

o contain

races f the

upper

varnish

ayers.

f

ndeed he

varnish

ayer

was

mastic

resin,

he

triterpenoid

omponents

would

not be

evident

uring

he course

of

a

chromatographic

nalysis,

under the conditions or

oil examination.

iterpenoid

esin

components,

s found

n

Venice

urpentine,

andarac,

osin

nd

others,

were

not observed.

Their

presence

n

samples

Al

to

C2

cannot be

ruled out

completely,

or the

stationary

phase employed

n

those

arly

ays

was not

deally

uited o thedetection

f small

mounts

of

these.

Unusual

peaks

werefound

n

those

amples

markedwith

n

asterisk

n

Table

2.

It

has not

been

possible

to

identify

hem

s

yet,

but,

coming

s

they

do in the

palmitate egion-

somewhat

arly

for the usual

diterpenes-onemay

opine

the

possible presence

f

some

form

f

spirit

arnish.

However,

hese

peaks

were not

superimposable

ith hose

of

any

benzoins

r balsams vailable

n-this

aboratory.

The

results rom his

imited

urvey

ead

one to conclude

hat

Bardwell

was not

n

the

habit

of

adhering

igidly

o

his

scheme.To

go

furtherhan

this

would be

dangerous,

ince

so

small

a

sample

may

not be

representative.

here

is, however,

ome small

measure

of

agreement

etween

is

theory

nd

his

practice.

Nevertheless,

t s

abundantly

pparent

hat

these

portraits

how

a

surprising

ariation

n

oil-type

rom ne

area to another.

As far s

I

am

aware,

they

re

unique

n

that

hey

ppear

to

contain

poppy-seed,

inseed nd

walnut

oils

as mediaon the

same

canvas.

A

greater

umber f

samples

would

give

results f

more

value than

ust

a few

n

isolation,

for

they

would enable

the

nvestigator

o

gain

an overall

picture

f the

trends. or

this

reason,

t

s

hoped

that more

xtendedxamination

fBardwell's

media

can be made

n

the oming ear. twill lso be ofgreatnterestocompare herange fmedia nBardwell's

workswith

hoseof his

contemporaries

n the British

chool.

Studies n

Conservation,

0

1975),

09-113




6/6

Anexamination

f

Thomas ardwell's

ortraits-the

edia

113

ACKNOWLEDGEMENTS

The

author

wishes

o

express

is

gratitude

o Miss

Joyce

lesters

nd Dr J.S.

Mills,

National

Gallery

aboratory,

ondon,

or heir ireless

elp

nd

encouragement

hroughout

his

work.Thanks re also dueto Mr M. KirbyTalley,Jr,withoutwhom hisstudywouldnot

havebeen

tarted,

or

isboundlessnthusiasm

nd

useful

iscussion.

REFERENCES

1

BARDWELL,

.,

The

Practice

of Painting

nd

Perspective

Made

Easy,

London

1756.

2

DossIE,

R.,

The

Handmaid

to the

Arts, vols.,

London 1758.

3

MILLS,

J.

S.,

'The

Gas

Chromatographic

xamination

f

Paint

Media. Part

',

Studies n Con-

servation,

1

(1966),

92-106.

4

MILLS,

J.

S.,

and

WHITE,

R.,

'The

Gas

Chromatographic

xamination

of

Paint

Media.Part

II',

Inc

Lisbon

Congress

Proceedings 1972).

uc,

London,

pp.

721-728.

Received0January974

RAYMOND

WHITE,

born

1944. Studied for

Royal

Institute of

Chemistryprofessional

examinations.

Specialized

n

analytical

roblems

nd

gas

chromatography

t

Brighton

olytechnic.

oinedNational

Gallery

969

where

e

s

engaged

n

study

f

the

rganic omponents

f

paintings.

Author'sddress:

National

allery, rafalgar

quare,

ondon

WC2N

DN,

Great

ritain.

Abstrait-Enutilisant

e la

chromatographie

n

phase gazeuse,

n

a

ex6cut6

es

analyses

des liants

huileux,

'une

s6rie

e

portraits

aits

ar

ThomasBardwell. es

r6sultats

nt

6t6

compares

vec

e

trait6

crit

ar

ui-meme ans

equel

l

consacre ne

section

u

broyage

e

pigments.

n certain

degr6

e concordance

6t6 onstat6.

Kurzfassung-Durch

ie

Anwendung

on

Gaschromatographie

urden

Analysen

von

Olmedienei einerReihevon PortraitsonThomasBardwell orgenommen.

Die Resultate

wurden

mit einer

igenenAbhandlung erglichen,

n

der

ein

Abschnittich

mit

er

Zerreibung

on Farbstoffen

efasst.

s

wurde

ine

gewisse

bereinkunft

estgestellt.

Riassunto-Con

'uso

di

cromatografiaaseoliquida

i

analizzarono

li

oli

adoperati

n

una

serie i

ritratti

el

pittore

homas

Bardwell. risultatiurono

aragonati

on

l

suo trattato

n

cui una

sezione

dedicata lla

macinazione i

pigmenti.

na certamisura i concordanza

stata

rovata.

Extracto-Se

realizaron

ndlisis

e mediosde aceite n

una

seriede

retratos

or

Thomas

Bardwell,

sando

a

cromatografia

e

gas liquido.

Los resultados ueron

omparados

on su

propio

ratado,

ue

dedica

una

secci6n

l molimientoe

pigmentos.

e

encontr6ierto

rado

de correlaci6n.

Studiesn

Conservation,

0

1975),

109-113


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