曜変天目 （油滴天目）
大名物
德川美術館 藏
這件器物的形狀與一般的天目碗不同，側面呈圓潤的碗形，高足較高且較大，中央經過內凹處理。釉色為暗紫色，釉面上密佈大小不一的銀色油滴斑紋，被認為是中國山西省懷仁窯的作品。雖然自古以來被稱為「曜變」，但釉面上銀色斑點密佈的特徵，根據現代分類應歸入「油滴」類。
This piece differs from the typical Tenmoku bowl shape, featuring a rounded bowl profile on the sides, a relatively high and large footring, with the center carved out. The glaze is dark purple, densely covered with silver oil-spot patterns of varying sizes, and is believed to originate from the Huairen kiln in Shanxi Province, China. Although historically referred to as "Yohen," the glaze's densely distributed silver spots are classified under the "Oil-Spot" category in modern terminology.
一般的な天目形とは異なり、側面が丸みを持った椀形をしており、高台は高く大きめで中央が刳られています。釉も暗紫色で、銀色の大小さまざまな油滴がびっしりと浮かんでおり、中国・山西省懐仁窯の産と考えられています。古くから「曜変」と呼ばれてきましたが、銀の班文がびっしりと表れた釉調は、現在の分類では「油滴」に入ります。
【中国・金時代 12-13世紀】
〔伝来〕樋口屋紹札―油屋紹佐―油屋浄祐―徳川家康―尾張徳川家初代義直高7.6 口径13.3 高台径4.5
德川家的傳承中，這件器物被稱為曜變天目，但以現代的知識來看，稱其為油滴天目更為妥當。
器物的胎土為白色，質地細膩且稍顯黏性，經過觸摸摩擦已部分變黑。高足碗的足部較大且高，高足內也被深深削刻，從胎土判斷，應為華北地區的產物。同龍光院及藤田美術館所藏的油滴天目應出自同一窯口。從器物外觀來看，其整體形狀與建窯天目的典型形狀有所不同，呈現出較為普通的碗形。從形狀分類來看，將其歸入天目瓷較為牽強，但古時凡此類釉面的器物似乎都被統稱為天目。
釉色為典型的深黑色，但並非如建窯天目釉面般厚重飽滿。從外側釉面流淌痕跡可見，沒有出現建窯天目那種明顯堆積的釉團，這是北方天目的特色之一。在釉面上，可以看到略帶棕褐色的銀色顆粒，即所謂的油滴。這些油滴分佈均勻，粒徑大小不一，整體呈圓形，用放大鏡觀察，可以發現這些顆粒是由金屬微小結晶聚合而成。
內壁的油滴分佈均勻，粒徑由下向上逐漸變小，這可能與器壁的曲率以及釉層厚度有關。相比之下，外壁的油滴分佈較為不均。即使是相對規整的一面，其分佈也不如內壁均勻；而高足對面的釉面，其油滴大小差異顯著，且釉面呈現出類似沸騰的麻點狀，光澤較為黯淡。這可能是因為燒成時火力不足，釉面出現吸收痕跡般的小孔亦與此相關。在靠近器足的釉團部分，油滴未能形成，僅見純黑的釉面。
觀察高足附近的釉線，可以注意到有紫色釉面向下流淌的痕跡。這種現象極為罕見，但對解開天目釉的秘密具有重要意義。建窯天目的高釉線部分通常被認為是一層釉料所形成，但實際上所有天目釉均為雙層釉。具體來說，底層施以含鐵的釉料，如島根縣出產的「來待石」（一種含氧化鐵的凝灰岩），然後在其上覆蓋一層薄薄的灰釉或水釉。上釉需控制不溢出底釉，並在燒製過程中與底釉充分融合，因此燒成後的釉面很難看出雙層結構。然而，這只茶碗因上釉微微流動，覆蓋到未施底釉的素胎上，從而揭示了其雙層釉的秘密，成為一件非常珍貴的實物資料。
值得補充的是，這層上釉中可能含有鉛成分。在燒製完成並窯爐冷卻的過程中，釉料經歷還原反應，作用於釉中的鉛成分，從而形成了那層帶有虹彩效果的光膜（即所謂的「拉斯特」效果）。
據傳，這只茶碗最初為堺的油屋常（淨）祐所有，後獻給將軍家，由家康在駿府將其傳予尾州義直，即所謂「駿河御讓物」。
德川油滴天目碗常见问题解答
什麼使德川油滴天目碗與眾不同？
這件天目碗在多方面與普通天目碗不同。其形狀更圓潤，具有較高且較大的高足，且高足內部經過深刻處理。釉色為深紫色，釉面密佈大小不一的銀色油滴斑紋。雖然歷史上被稱為「曜變」，但根據現代分類，它屬於「油滴」類天目碗。此碗來源於中國山西省的懷仁窯。
為什麼這隻碗現在被歸類為「油滴」而不是「曜變」？
歷史上，德川家族將此碗稱為「曜變天目」。然而，當代陶瓷分類更加注重釉面密佈的銀色斑點這一特徵，因此該碗被歸入「油滴」類，而非「曜變」。
製作此碗所用的胎土有何特點？
此碗的胎土為白色，質地細膩且稍帶黏性。經過長時間觸摸摩擦，部分區域已變暗。其高足大而高，內部經過深刻處理，顯示出北方中國的產地特徵，可能與龍光院及藤田美術館藏品出自同一窯口。
此碗的釉面與建窯天目碗有何不同？
與建窯天目碗厚重豐盈的釉面不同，此碗的釉面呈深黑色，但不如建窯釉面那麼厚實。釉面沒有建窯碗在邊緣常見的釉流堆積現象，這是北方天目的特色之一。釉面上的銀色油滴大小不一，主要呈圓形，放大觀察可見其由細小金屬結晶聚合而成。
油滴在碗的表面分佈均勻嗎？
內壁上的油滴分佈均勻，隨著靠近碗口逐漸變小，這可能與碗壁的弧度及釉層厚度有關。然而，外壁的油滴分佈較不均勻。一側的分佈較為整齊，但另一側的油滴大小差異明顯。該面釉面呈現粗糙的麻點狀，光澤黯淡，可能是燒制火力不足所致。
這隻碗的釉面有哪些獨特特徵揭示了天目釉技術？
在高足附近，紫色釉流延伸至未施釉的胎土上，這是一種罕見現象，揭示了天目釉的雙層結構。底層釉為含鐵釉，上層釉則為薄薄的灰釉或水釉。通常在燒制過程中，上下兩層釉料會充分融合，而此碗的釉流暴露了這一結構，使其成為研究天目釉技術的重要資料。
鉛可能在碗釉中發揮了什麼作用？
上層釉料可能含有鉛成分，在燒制完成並冷卻的過程中，釉料經歷了還原反應，這一反應作用於釉中的鉛，形成了釉面上可見的虹彩光膜（類似「拉斯特」效果）。
德川油滴天目碗是如何進入德川家族收藏的？
此碗原屬堺市的油屋常（淨）祐，後獻給德川幕府。德川家康將其傳予駿河的尾張德川義直，因此被稱為「駿河御讓物」。
徳川家の伝来では、曜変天目ということになっていますが、今日の知識からすれば、油滴とするのが妥当でしょう。
土は、白いねっとりした細緻な質で、手ずれで黒ずんでいます。高台は大きく、高く、高台内も深ぐ削り込んでいます。明らかに華北の産と知れます。竜光院や藤田美術館の油滴天目と同所の産でしょう。外から見た全体の形も、建窯のそれとはかなり違って、普通の碗形りをしています。形の分類からすれば、ちょっと天目には入れにくいものですが、昔はこの釉だちのものは、すべて天目と汎称したらしいです。
釉色は、例によって深い黒、ただし建窯の釉のように厚くたっぶりとはしていません。
外側の釉切れの部分にしても、あのまくれ上がるような、釉だまりは見られません。これは北方の天目の一つの特色といえましょう。その釉の表面にわずかにセピアがかった銀色の粒、いわゆる油滴がびっしりと浮かんでいます。もっとも油滴の粒は一様ではなく、大きいのもあれば小さいのもあります。だいたいにおいて円形に近い結び方をしています。拡大鏡で見ると金属の細かい結晶が凝集したものと認められます。
内面についていいますと、油滴は均質でむらなく散っています。上へゆくほど粒が細かくなるのは、器壁のカーブの加減、つまり釉の厚さのせいでしょう。これに対して外面は、あまり油滴のそろいがよくありません。側面の図に見られる面は、それでもまだよくそろっているほうですが、反対側の面（高台の図の面）では、大小の差が激しいです。しかも釉が、煮えたようにあばた状を呈し、艶も鈍いです。火が甘かったと思われます。釉面に吸い込みあとのような孔があるのも、そのせいでしょう。裾のやや盛り上がった釉だまりの部分には、油滴が結ばず、漆黒の釉だけが見えます。
高台のほうの図を注意して見ますと、釉ぎわから高台わきにかけて、紫がかった釉の、なだれがあることに気づくでしょう。こういう現象は、きわめて例が少ないですが、天目釉の謎を解重要な鍵なのです。建窯の天目の、盛り上がった釉ぎれの部分を見ていますと、天目の釉は、一重のものとしか考えられませんが、実はすべて二重釉なのです。
すなわち、下にキマチ（来待。島根県に産する酸化鉄を含んだ凝灰岩。赤瓦などの釉の原料）のような含鉄釉料をかけ、さらに薄い灰釉のような、水釉をかけて焼くのです。上の釉は、下釉からはみ出ないようにかけられますし、焼成中に下釉とよく溶け合って、焼き上がりの釉面かゐは、それと見抜くことはむずかしいです。ところが、この茶碗では、たまたま上釉がわずかに流れて下釉のない素地の上に及んだわけです。その点、まことに貴重な資料といわなければなりますまい。
ちなみに付け加えておきますと、この上釉にはおそらく鉛分が含まれているに違いありません。茶碗が焼き上がり、窯が冷えてゆく過程で還元が起こり、それが上釉の鉛分に作用してあの虹彩（一種のラスタ）膜を、つくることになるらしいのです。
伝来は、もと堺の油屋常（浄）祐の所持。のちに将軍家に献上され、家康から、駿府において尾州義直に譲られた、いわゆる駿河御譲りものです。
In the Tokugawa family tradition, this artifact has been regarded as a Yohen Tenmoku, but with modern knowledge, it is more appropriate to classify it as an Oil-Spot Tenmoku.
The clay is white, fine, and slightly sticky, with areas darkened due to handling over time. The footring is large and high, with the interior deeply carved, suggesting its origin in northern China. It likely comes from the same production site as the oil-spot Tenmoku bowls housed in Ryuko-in and the Fujita Art Museum. The overall shape, as seen from the outside, differs significantly from the typical Jian ware profile and is closer to a regular bowl shape. While it might not easily fit the formal classification of Tenmoku ware by shape, it appears that in ancient times, all wares with this kind of glaze were broadly referred to as Tenmoku.
The glaze is a deep black, as expected, but it is neither as thick nor as rich as the glaze seen in Jian ware. The glaze at the rim does not form the prominent pooling or flowing characteristic of Jian ware, which is a notable feature of northern Tenmoku. The surface of the glaze is densely covered with small silver specks, known as oil spots. These oil spots vary in size, with larger and smaller spots appearing together and mostly forming circular patterns. Under magnification, the spots appear as aggregates of fine metallic crystals.
On the interior surface, the oil spots are evenly distributed without significant irregularities. The spots become smaller toward the rim, which could be due to the curvature of the bowl and variations in glaze thickness. In contrast, the oil spots on the exterior are less uniform. One side of the bowl shows a relatively consistent pattern, but the opposite side, as seen in the footring view, exhibits significant variation in the size of the spots. Additionally, the glaze surface in this area appears pitted and rough, with a dull sheen, likely due to insufficient firing. Small pores resembling absorption marks are also visible, probably caused by the same issue. In the slightly raised pooled glaze near the foot, no oil spots are present, leaving only the jet-black glaze.
Observing the area near the footring, a flow of purple-tinted glaze can be seen extending from the edge of the glaze line. This phenomenon is extremely rare but provides crucial insights into the mysteries of Tenmoku glazes. While the pooled glaze lines of Jian ware Tenmoku are typically thought to be formed by a single layer of glaze, it is now understood that all Tenmoku glazes are double-layered. Specifically, a layer of iron-rich glaze, possibly made from a material like Kimachi stone (a tuff stone containing iron oxide from Shimane Prefecture), is first applied, followed by a thin layer of ash glaze or water glaze. The upper glaze is carefully applied to avoid overflowing the lower layer and fuses well during firing, making it difficult to discern the double-layer structure in the finished glaze. However, on this bowl, the upper glaze has slightly flowed onto an unglazed area, revealing the double-layer structure. This makes it an invaluable artifact for studying Tenmoku glaze technology.
It is also worth mentioning that the upper glaze likely contains lead. During the cooling process after firing, a reduction reaction may have occurred, acting on the lead in the upper glaze to produce the iridescent film (a type of "luster" effect) visible on the surface.
According to tradition, this bowl was originally owned by Tsunejo (Joyo) of the Yoya oil shop in Sakai. It was later presented to the Tokugawa shogunate and passed from Tokugawa Ieyasu to Tokugawa Yoshinao of the Owari domain in Suruga, becoming known as the "Suruga Gift."
Tokugawa Oil-Spot Tenmoku Bowl FAQ
What makes the Tokugawa Oil-Spot Tenmoku bowl unique?
This bowl stands out from typical Tenmoku bowls in several ways. Its shape is more rounded with a taller and larger footring, and its center is carved out. The glaze is dark purple with densely packed silver oil spots of varying sizes. While historically known as "Yohen," modern classification places it as "Oil-Spot." It originates from the Huairen kiln in Shanxi Province, China.
Why is the bowl now classified as "Oil-Spot" rather than "Yohen"?
Historically, the Tokugawa family referred to the bowl as "Yohen Tenmoku." However, contemporary understanding of ceramic classification emphasizes the glaze's densely packed silver spots as the defining characteristic, aligning it with the "Oil-Spot" category rather than "Yohen."
What are the characteristics of the clay used to create the bowl?
The bowl's clay is white, fine, and slightly sticky. Handling over time has darkened some areas. The large and high footring, with its deeply carved interior, points to its origin in northern China, possibly from the same kiln that produced similar bowls found in the Ryuko-in and Fujita Art Museum.
How does the glaze on this bowl differ from that of Jian ware Tenmoku bowls?
Unlike the thick, rich glaze of Jian ware, this bowl's glaze is a deep black but not as thick or heavy. The glaze doesn't pool or flow at the rim as seen in Jian ware, a characteristic of northern Tenmoku. The silver "oil spots" on the surface are not uniform in size, ranging from large to small, and are primarily circular. Under magnification, they reveal themselves to be aggregates of fine metallic crystals.
Are the oil spots distributed evenly across the bowl's surface?
The interior surface boasts evenly distributed oil spots that become smaller towards the rim, likely due to the bowl's curvature and variations in glaze thickness. The exterior, however, shows less uniformity. While one side displays relative consistency, the opposite side features significant variation in spot size. This side also exhibits a pitted, rough texture with a dull sheen, suggesting insufficient firing.
What unique glaze feature reveals information about Tenmoku glaze techniques?
Near the footring, a flow of purple-tinted glaze extends onto the unglazed clay, a rare phenomenon. This reveals the double-layered nature of Tenmoku glazes. A base layer of iron-rich glaze is covered by a thin layer of ash or water glaze. This usually blends seamlessly during firing, but the flow in this bowl exposes the two layers, making it a valuable artifact for studying Tenmoku glaze techniques.
What role does lead potentially play in the bowl's glaze?
The upper glaze likely contains lead, which may have undergone a reduction reaction during the cooling process after firing. This reaction on the lead potentially produced the iridescent film, similar to a "luster" effect, seen on the surface.
How did the Tokugawa Oil-Spot Tenmoku bowl come to be in the Tokugawa family's possession?
Originally owned by Tsunejo (Joyo) of the Yoya oil shop in Sakai, the bowl was later presented to the Tokugawa shogunate. Tokugawa Ieyasu then passed it on to Tokugawa Yoshinao of the Owari domain in Suruga, hence becoming known as the "Suruga Gift."
Comments