５）洋紙作品の安定化処理および修理
はじめに
東京国立博物館は陸前高田市立博物館が所蔵する絵画作品の安定化処理と修理を行っています。対象作品は東北地方太平洋沖地震による大津波で被災したもので、その中の洋紙作品（版画、水彩画、アクリル画等）作業に従事しました。2013年から、効果的な安定化方法を模索して様々な実験を行ってきました。そして現在、その結果に基づき少しずつ作品の処置をしています。ここではこれまでの実験で得られた情報を中心に現段階での安定化処理状況を報告します。

水を用いた洗浄は洋紙作品修理の最も有効な方法の１つで水を通過させることで紙の繊維内に残留した汚れを洗い流すことができます。残留した塩分を除去するためにこの方法を用いました。脱塩後の廃液に残留する塩化物イオン濃度の目標値は6ppmに設定しました。作品自体に残留する塩分の計測は蛍光X線分析及び塩化物試験紙を用いました。塩化物試験紙の目盛りは0.2刻みで1 ～ 10まであります。測定可能な最小値は1.2（ppmに換算するとNaClは50ppm、Cl は30ppm）です。水道水を測定すると目盛1でした。そのため塩化物試験紙での計測結果の目標は目盛り1以下に設定しました。実験の手順は以下のとおりです。

作品の状況対象となる洋紙作品はすべて、2011年3月11日に被災後、同年8 〜 9月にかけて全国美術館会議の主導でエタノー
ル、TBZによる殺菌、ドライクリーニング等の応急処置が施されています。それから約３年間は岩手県立美術館収蔵庫内の安定した環境で保管されていたため、状態に大きな変化はなかったと思われます。作品群に共通してみられる損傷は海水、汚水に浸水したことによる黴、シミ、変形です。特に黴の発生により、黒、茶色、薄いピンク色や黄色など様々な色素が固着しました。シミは主に泥水や錆、テープ痕、他の作品から溶解した色材の付着などです。

実験の手順①オリジナル作品中に残留した塩素を蛍光X線分析装置で分析。 ②作品と同じ種類の紙（紙：BBケント紙）を入手し、人工海水（人工海水マリンソルト200L用・株式会社カイスイマレン）に浸漬後乾燥させてテストピースを作成。 ③実験前のテストピースの塩素を蛍光X線分析装置で分析。塩化物試験紙（Chloride QuanTab® TestStrips, 30-600mg/L, Titrators for Chloride Low Range・HACH社）でも計測（画面側の９ヶ所）。 ④上記のテストピースを使用し、以下のa. ～ g.の方法で各々実験。繰
り返す度に塩化物試験紙で塩化物イオン濃度を測定。
⑤実験後のテストピースを蛍光X線で分析。
a. サクション法：画面側を上にし、サクションテーブルで５分間吸引しつつ３分間水300mlを全体に噴霧するこ

安定化処理のための実験

5) Stabilization and Repair of Artworks on Modern Paper
Introduction
The Tokyo National Museum has been working on stabilizingand repairing the RTCM’s collection of artwork damaged by thetsunami in 2011. We are engaged in the treatment of artworkon modern paper (prints, watercolor paintings, and acrylicpaintings). Researching for effective stabilization methods, wehave been conducting various experiments since 2013. Basedon the results of these experiments, we are currently treating
the artwork carefully. Focusing on the data obtained from theexperiments, our current stabilization treatment is described inthis section.
Artwork condition
For all damaged artwork on modern paper involved in thisproject, temporary treatments, including sterilization withethanol or TBZ and dry cleaning, were performed from Augustthrough September 2011 under the guidance of the JapaneseCouncil of Art Museums. Since they were stored in a stableenvironment at the repository of the Iwate Museum of Art
for approximately three years after treatment, it is assumed
that no significant change has occurred in the condition of theartwork. Common damage to the artwork was mold, stains
and deformation caused by being soaked in seawater andcontaminated water. Pigments of various colors such as black,brown, light pink, and yellow have affixed to the drawings
because of mold. The stains include those caused by muddy
water and rust, tape marks, and the attachment of coloredmaterial that dissolved from other works of art.
Experiments conducted in preparation for stabilization
One of the most effective methods for stabilizing artwork on
modern paper is washing with water. By running water throughthe artwork, contaminants remaining in the fibers of the paper
are washed away. This method was employed to remove102

residual salt. The target value for the concentration of residual
chloride ions in the discharged liquid from the desalination
process was set at 6 ppm. Salt remaining in the artwork itself
was measured by employing fluorescent X-ray analysis andchloride test strips. The scale of the chloride test strip ranges
from 1 to 10 with increments of 0.2. The minimum value thatcan be measured is 1.2 (50 ppm for NaCl and 30 ppm for Cl-).
The chloride test strip indicated scale 1 for tap water . Thus,
the target value on the test strip was set at scale 1 or less. The
experimental procedure is explained below.
Experiment procedure(1) Chlorine remaining in the artwork was analyzed by anX-ray fluorescence analyzer. (2) The same type of paper used
for the original artwork (BB Kent paper) was obtained. Sheetsof this paper were soaked in artificial seawater (“Marine-Saltfor 200L”; Kaisuimaren Co., Ltd.) and then dried to create
test pieces. (3) Chlorine in the pre-experiment test pieces
was analyzed using an X-ray fluorescence analyzer. It wasalso measured by chloride test strips (Chloride QuanTab®
Test Strips, 30-600 mg/L, Titrators for Chloride Low Range;
Hack Company) at 9 points on the front side of the test pieces.
(4) Experiments were conducted using these test pieces byemploying the following methods a. through g. Each time atreatment was repeated, the chloride ion concentration wasmeasured using chloride test strips. (5) Post-experiment test
pieces were analyzed by fluorescent X-ray.
a. Suction Method: A test piece was placed on a suction tablewith its front side facing up. While suctioning for five minutes,
the entire test piece was misted with 300 ml of water for threeminutes. This process was performed repeatedly.
b. Blotting Method: A test piece was placed on a piece ofblotting paper, which had been soaked with a considerable
amount of water, with its front side facing up, and left for 10minutes. This process was performed repeatedly (the blotting第4章
表1

洗浄法の比較実験結果

Table 1

方法
Test namea

サクション法Suction Methodb

ブロッティング法
Blotting Method

安定化処理と修理

Results of a comparative experiment of washing methods

実験前の噴霧処理1)
Mistingprior to theexperiment1)
WEW
E
Wc

浸漬法（10分間）
Soaking Method (10 min.)d

短時間浸漬法（3分間）
Short Duration Soaking Method(3 min.)

e

温水浸漬法
Warm Water Soaking Method(25°C, 30°C, 35°C and 40°C)

Ef

温水噴霧＋サクション法
Warm Water Misting + Suction
Method(25°C, 30°C, 35°C and 40°C)

Eg

流水法
Running Water Method

EEW
E

備考
Remark
4回で0に近くなる。
Came close to 0 after 4 treatments.
2回で0に近くなる。
Came close to 0 after 2 treatments.
4回である程度減少しその後横ばい。
Concentration was reduced to a certain extent after
4 treatments and then the values leveled out.
3回である程度減少しその後横ばい。
Concentration was reduced to a certain extent after
3 treatments and then the values leveled out.
4回で0になる。
Reached 0 after 4 treatments.
2回で0になる。
Reached 0 after 2 treatments.
4回で0に近くなる。
Came close to 0 after 4 treatments.
2回で微量になり、その後横ばい。温度による差はほとんど見られない。
Concentration was reduced considerably after
2 treatments and then the values leveled out.
Differences in temperature had little effect on theoutcome.
3回で0に近くなる。温度による差はほとんど見られない。
Came close to 0 after 3 treatments. Differences intemperature had little effect on the outcome.
2回である程度減少するがそれ以降横ばい。
Concentration was reduced by a certain extent after
2 treatments and then the values leveled out.
2回である程度減少するがそれ以降横ばい。
Concentration was reduced by a certain extent after
2 treatments and then the values leveled out.

塩分濃度（単位：目盛数）2)
Salinity concentration 2)(unit: strip scale)
実験前
最終回
Pre-experiment Last measurement

実験回数
Number ofexperiments

所要時間
（分）
Experimenttime (min.)420

100.0221070.02

660

91.1

770

91.24

440

2.8

0220

2.11

0412

100.26220-309.53

0.863159.850.12315100.55

420100.931）E: 実験前に40％のエタノール水溶液を噴霧。 W: 実験前に純水を噴霧。
2）塩化物試験紙による塩分濃度測定結果（数字は目盛数の測定箇所全体での平均値）。
1）E: 40% ethanol was sprayed prior to the experiment. W: Deionized water was sprayed prior to the experiment.
2）Results of salinity concentration measurement using chloride test strips (values are the average of the results of the entire area measured).

図1 塩化物イオン濃度と脱塩時間の関係
Fig. 1 Relationship between chloride ion concentration anddesalination time

図2 塩化物試験紙による計測実験
Fig. 2 Experiment using chloride test strips

図3 ハンディイオンメータで塩化物イオン濃度を計測
Fig. 3 Measuring chloride ion concentration using a Handy Ion Meter103

とを繰り返す。 b. ブロッティング法：十分な量の水で濡らした吸取紙の上に画面側を上にしてのせ、10分間おくことを繰り返す（吸取紙は毎回交換）。 c. 浸漬法（10分間）：3Lの水に10分間浸漬を繰り返す。 d. 短時間浸漬法（３分間）：3Lの水に３分間浸漬を繰り返す。 e.
温水浸漬法：25℃・30℃・35℃・40℃の温水3Lに各々 10分間浸漬を繰り返す。 f. 温水噴霧＋サクション法：４枚のテストピース各々に25℃・30℃・35℃・40℃の温水を噴霧し、各々サクションテーブルで５分間吸引しつつ３分間水300mlを全体に噴霧することを繰り返す。 g.
流水法：バットに20L水を貯めた中にテストピースを浸漬し、その中に１分間に100mlの勢いで水を流し続け５分ごとに引き上げる。
なお、いずれの方法も処理前にエタノール40％水溶液を噴霧しました。また、a 〜 c および g については処理前に純水を噴霧する方法でも実験を行いました。
実験結果
実験の結果、「短時間浸漬法」が最も早く確実に脱塩できることがわかりました（表1）。また、浸漬の前にエタノール水溶液を噴霧すると紙の繊維の中まで水が入り、脱塩効果が高まると同時に時間を短縮できました。
実際の安定化処理と修理
作品はリトグラフで、水に溶解しないインクだったた
め短時間浸漬法で安定化処理を行いました。手順は次のpaper was replaced each time).
c. Soaking Method (10 minutes): A test piece was soakedin 3 L of water for 10 minutes. This process was performed
repeatedly.
d. Short Duration Soaking Method (3 minutes): The processof soaking a test piece in 3 L of water for three minutes wasperformed repeatedly.
e. Warm Water Soaking Method: Test pieces were soakedin 3 L of water at temperatures of 25, 30, 35, and 40°C for 10minutes, respectively. This process was performed repeatedly.
f. Warm Water Misting + Suction Method: Four test pieces
were misted with warm water at temperatures of 25, 30, 35, or
40°C. Then, while suctioning for five minutes using a suction
table, the entire area of test pieces was misted with 300 ml ofwater for three minutes. This process was performed repeatedly.
g. Running Water Method: A test piece was placed in a tray
filled with 20 L of water. Then water was continuously supplied
to this tray at a speed of 100 ml per minute. The test piece wasremoved every 5 minutes.
A 40% ethanol solution or deionized water was misted before
each method.
Results of the experiment
The results of these experiments showed that the Short
Duration Soaking Method was the fastest and most reliable
method for desalination of the test pieces (Table 1). It was also
found that desalination efficiency improved and the required
time is reduced when the test pieces were sprayed with a 40%
ethanol solution prior to soaking.
Actual stabilization and repair
A disaster-damaged lithograph was treated. Since ink that isinsoluble in water had been used, the drawing was stabilizedusing the Short Duration Soaking Method. The following
procedure was employed: (1) the drawing was cleaned in a dry

104

とおりです。①練り消しゴムで乾式洗浄 ②作品裏面からエタノール水溶液を噴霧し水の浸透性を高め、短時間浸漬法を５回繰り返す ③pH9に調整した水酸化カルシウムで脱酸処置（フロート法） ④過酸化水素水、水素化ホウ素ナトリウムで黴とシミを漂白 ⑤水洗後上記と同様の方法で脱酸 ⑥加圧乾燥で変形修正安定化処理および修理の結果と効果
短時間浸漬法では１回ごとに、脱塩時の廃液の塩化物イオン濃度を測定器（ハンディ塩素イオンメータTiN5102I・株式会社東興化学研究所）で計測しました。１回目は117ppmでしたが、５回目は0.69ppmに下がりました。
塩化物試験紙では目盛0でした。実験をふまえた実践でも十分な効果があることが分かりました。
黴の漂白では、黒色部位は完全には除去できませんでしたが、部分的に薄くなるものもありました。薄い茶色や黄色、ピンク色などの色素には有効でした。全体に波打つような変形は加湿後加圧乾燥することにより、本来の自然な形状に戻りました。シミは今回の作品には見られなかったので、今後の作業で研究を進める予定です。
本実験には西原紀恵氏（絵画修復家）、土屋裕子氏、和田浩氏、神庭信幸氏（東京国立博物館）、山領まり氏（絵画修復家）が参加しました。
米倉乙世（紙・書籍保存修復技術者）

state using a kneaded eraser; (2) the drawing was sprayed fromthe back with an ethanol solution to enhance water permeability,
and then treated with the Short Duration Soaking Method. Thiswas repeated five times; (3) deoxidation (float method) wasperformed using calcium hydroxide adjusted to pH9; (4) moldand stains were bleached using a hydrogen peroxide solution
and sodium borohydride; (5) after washing with water, thedrawing was deoxidized using the above described method; and(6) deformation was corrected by press drying.
Results and outcome of stabilization and repair work
While performing the Short Duration Soaking Method, theconcentration of chloride ion in the desalination discharged
liquid was measured after each treatment using Handy
Chlorine Ion Meter TiN-5102i (TOKO Kagaku Co., Ltd.). The
concentration level was 117 ppm at the first measurement, andwas reduced to 0.69 ppm at the fifth measurement. The chloride
test strip indicated a scale reading of 0. Thus, it was foundthat this method was also sufficiently effective on the originalartwork.
After bleaching the mold, the black stains could not be
removed completely, but the color partially faded. The
bleaching treatment was effective for removing light brown,
yellow, pink, and stains of other colors too.
The wave-like deformation of the entire artwork was returned
to its original, natural form by press drying after dampening it.
Although stains were not observed in this artwork, experiments
for removing stains will be required for future treatment.
The experiments were performed by the author Otoyo
Yonekura, Norie Nishihara (painting conservator), Yuko
Tsuchiya, Hiroshi Wada, Nobuyuki Kamba (Tokyo NationalMuseum) and Mari Yamaryo (painting conservator).

Otoyo Yonekura (Paper & Book Conservator)

第4章

安定化処理と修理

図4 短時間浸漬法：水を張ったバットに順に浸漬する
Fig. 4 Short Duration Soaking Method: The artifacts are soaked one by one
in a series of water-filled trays

図5 塩化物試験紙で、作品に残留した塩化物イオン濃度を測定する
Fig. 5 Concentration of chloride ions remaining in the artifact ismeasured using chloride test strips

図6 フロート法で脱酸処置する
Fig. 6 Deoxidation using the float method

図7 漂白作業
Fig. 7 Bleaching process

図8 漂白前の黴（部分）Fig. 8 Pre-bleaching mold on artwork (partial)

図9 漂白後の黴（図8と同じ部分）
Fig. 9 Post-bleaching mold on artwork (same area as Fig. 8)105