Tang dynasty qin surfaces feature black or chestnut-shell-colored lacquer. Beneath this lies a pure deer-antler cement (made from crushed antler). The lacquer layer is both resilient and slightly porous — protecting the instrument while enhancing resonance for superior tone quality. Underneath the plaster base, hemp cloth (葛布 kebu) was traditionally wrapped around the body to prevent cracking at the joint connecting the top and bottom boards.

到了宋朝，灰胎下裹以葛布者則不多見了。北宋晚期，出現了八寶灰（鹿角灰中混以黃金、白銀、珍珠、玉石、瑪瑙、珊瑚、貝殻等碎屑，如明·仲尼式琴）。凡使用八寶灰之琴，如滿天繁星。但此種琴也較為少見。

By the Song dynasty, hemp cloth reinforcement became rare. In the late Northern Song period, "eight-treasure cement" emerged (the deer-antler cement combination mixed with gold, silver, pearl, jade, agate, coral, and shell fragments — something especially common on Ming dynasty Zhongni-style qins). Instruments with this type of cement shimmer like a starry sky, though such examples remain scarce.

明·仲尼式琴 Ming dynasty Zhongni-style qin

到了明朝，除黑色及栗子殻色以外，朱漆之琴也已較為常見。除鹿角灰、八寶灰外， 也使用瓦灰，另有由中藥（無名異）等合成的雜類灰。就質量而言，仍以鹿角灰為最好。 而明以後之琴的灰胎，比唐、宋之琴，一般相對較薄。

During the Ming dynasty, vermilion lacquer became common alongside black and chestnut tones. Beyond deer-antler and eight-treasure cement, tile dust cement and **herbal composite cement (using minerals like wumingyi) appeared. In terms of quality, deer-antler cement remained superior. Ming-era cement bases were generally thinner than those on Tang and Song qins.

斷紋的種類很多。主要的有：
Crackle patterns are numerous. Major types include:

1. 梅花斷 meihua duan (Plum Blossom Cracks)
2. 牛毛斷 niunao duan (Ox Hair Cracks)
3. 蛇腹斷 shefu duan (Snake Belly Cracks)
4. 冰紋斷 bingwen duan (Ice Cracks)
5. 流水斷 liushui duan (Flowing Water Cracks)
6. 龍鱗斷 longlin duan (Dragon Scale Cracks)
7. 龜紋斷等 guiwen duan (Tortoise Shell Cracks)。

(Looking at the descriptions with the images below it seems that many combine more than one type of crackle.)

梅花斷紋示意圖 Plum Blossom Crackle schematic diagram
（梅花斷間流水、牛毛斷紋 Plum Blossom with Flowing Water/Ox Hair crackles）
 

牛毛斷紋示意圖 Ox Hair Crackles
 

蛇腹斷紋示意圖 Snake Belly Crackles
 

冰紋斷紋示意圖 Ice Crackles
 

流水、牛毛斷 Flowing Water/Ox Hair Crackles
 

流水、牛毛斷 Flowing Water/Ox Hair Crackles
 

流水斷紋示意圖
Flowing Water Crackles Schematic Diagrams

一般來說，琴不過百年不出斷紋，而隨年代久遠程度不同，斷紋也不盡相同。 所以，斷紋也是判斷古琴古老程度的主要依據之一。如《琴箋》所說：

最古的梅花斷、牛毛斷，當然非常罕見。而唐、宋之琴一般以蛇腹斷為主，雜有流水斷、冰紋斷等斷紋。

Generally, crackles do not appear until a qin is over a century old, with patterns varying by age. Thus, crackle patterns serve as key indicators of a qin’s antiquity. As the Treatise on the Qin (Qin Jian) notes:

Plum Blossom and Ox Hair patterns—signifying extreme age—are exceptionally rare. Tang and Song qins typically exhibit Snake Belly patterns mixed with Flowing Water or Ice Cracks.

蛇腹、流水及冰紋斷 Snake Belly with Flowing Water/Ice Cracks
 

蛇腹及流水斷 Snake Belly with Flowing Water Cracks
 

蛇腹間冰紋斷 Snake Belly with Ice Cracks
 
 

琴上的斷紋形狀和漆灰的關係也很大，如明朝以後之琴，由於漆灰質量的變化，加之漆層較薄，斷紋種類反而較多，主要有：蛇腹斷、流水斷、冰紋斷、牛毛斷、龍鱗斷、龜紋斷等。

Crackle patterns also correlate with the quality of the cement. Post-Ming qins, with their thinner lacquer and various types of cement, often display diverse patterns: Snake Belly, Flowing Water, Ice Cracks, Ox Hair, Dragon Scale, and Tortoise Shell.

琴上有好的斷紋，不僅是古代文物的佐證，同樣也使古琴更加美觀，又使古琴的聲音更加松透古雅，音色更妙。

Fine crackle patterns not only can authenticate a qin’s antiquity but also enhance its beauty, while lending the tone a resonant, archaic elegance.

當然，並不見得琴上斷紋越多就越好。有些斷紋裂開翹起，有礙彈奏，則應當修復了。

That said, excessive cracking that impedes play (e.g., raised flakes) requires restoration

此外，也有偽造斷紋的，其手法主要是刀刻或以高熱作用制做等。但偽造的斷紋大失自然，對行家來說，是很容易看破的。

Finally, there are also artificially created crackles. These include ones carved with knives, induced by heat and so forth. However, these false crackles appear unnatural and are easily spotted by connoisseurs.