I. Different Raw Materials

For the same grade among the "Four Bricks," the raw material requirements for Black Brick and Flower Brick are higher than those for Fu Brick and Green Brick; comparing Black Brick and Flower Brick, the raw material quality for Flower Brick is slightly superior to Black Brick; for the same grade, the raw materials for Fu Brick and Green Brick are similar. Fu Brick requires "flowering" so it is pressed slightly looser, while Green Brick is tighter.

Black Brick Tea: Historically, Black Brick Tea raw materials were divided into "surface tea" and "inner tea." Surface tea was grade two or three dark rough tea, while the "inner" part used grade three, four dark rough tea, and some reformed raw dark tea. After 1968, this distinction was abandoned, switching to mixed pressing.

Flower Brick Tea: Flower Brick evolved from the Flower Roll (Qian Liang Tea). It primarily uses grade three dark rough tea, blended with some grade two dark rough tea, and does not incorporate raw dark tea or poorer quality dark rough tea.

Fu Brick Tea: Fu Brick is divided into "Special Fu Brick" (Special Fu) and "Common Fu Brick" (Common Fu). Special Fu Brick uses entirely grade three dark rough tea as raw material, blending some grade four dark rough tea considering the quality differences between spring/summer tea and regional variations. Common Fu Brick raw material is mainly grade four dark rough tea, blended with some grade three rough tea.

Green Brick Tea: Divided into surface, secondary surface, and inner tea. The outermost layer is called the surface, processed from grade one raw dark tea, of the best quality; the next layer is called the secondary surface, processed from grade two raw dark tea, of secondary quality; the main central part is called the inner tea, also known as the core, of slightly poorer quality. Surface tea initial processing involves seven steps: fixation, initial rolling, initial sun-drying, re-frying, re-rolling, pile-fermentation, and sun-drying. Inner tea involves four steps: fixation, rolling, pile-fermentation, and sun-drying.

II. Different Processing Methods

Black Brick Tea and Flower Brick Tea share the same pressing process: first, the rough tea is screened and impurities removed for raw material blending. Then it goes through weighing, steaming, machine pressing, cooling, brick removal, brick inspection, drying, and packaging. The time in the drying room is about 10 days, with gradual temperature increase, reaching up to 70 degrees Celsius when exiting. Flower Brick Tea has斜条花纹 (oblique stripe patterns) pressed on its four sides.

Fu Brick Tea: Its pressing procedure is basically the same as Black and Flower Brick, but because of Fu Brick's unique "flowering" process which requires the brick to be moderately loose to facilitate microbial activity, the press machine pressure is lower. To promote "flowering," drying is not rushed; the entire drying period is more than twice as long as for Black and Flower Brick. The flowering period in the drying room is about 15 days, followed by a drying period of about 5 days.

Under specific temperature and humidity conditions, "Eurotium cristatum" grows rapidly in Fu Brick Tea, forming golden-yellow spore sacs, commonly called "golden flowers." Traditional Fu Tea selected grade three and four dark rough tea as raw material. This material has thin leaves, deep color, a certain stem content, and high inorganic element content, meeting the requirements of the traditional Fu tea special production process. Modern production uses scientific and precise mechanization and assembly line operations, thoroughly improving product quality and increasing yield. Technologically, it has broken through the traditional notion that no stems mean no flowering, allowing high-grade Fu tea to maintain traditional flavor while enhancing its health benefits and product grade.

The production technique of Anhua Fu Brick Tea has been listed as a national intangible cultural heritage. The natural fermentation process for Fu Brick Tea is considered better in Jingyang.

Green Brick Tea: When stored, the rough tea is only 70-80% dry. It is piled in warehouses with ventilation channels for natural fermentation for about 3 to 6 months before processing into Green Brick Tea. The pressing and drying process is similar to Black Brick Tea, but the tea brick is pressed tighter.

III. Different Quality Requirements

Black Brick Tea requires uniform brick surface, dark brown exterior color, pure aroma,允许稍有松烟香 (allowing a slight pine smoke aroma); pure and thick taste slightly astringent, reddish-yellow and slightly dull liquor, dark brown wet leaves. Aged tea has camphor aroma and a mellow taste.

Flower Brick Tea requires consistent brick surface, dark brown color, pure aroma, with pine smoke aroma; strong, pure, and smooth taste; reddish-yellow liquor, fairly even dark brown wet leaves. Aged tea has camphor aroma and a mellow taste.

Special Fu Brick requires yellowish-brown exterior, slightly loose brick. Upon opening the brick, it should have "abundant golden flowers," golden yellow color, large颗粒 (particles); pure aroma, with "fungal floral" aroma; mellow taste, with "fungal floral" flavor; reddish-yellow and fairly bright liquor; fairly even dark brown wet leaves. Common Fu Brick has slightly lower requirements than Special Fu Brick. Aged Fu Brick requires a strong fungal floral aroma.

Green Brick Tea requires bluish-brown exterior color, pure aroma,尚浓无青气 (fairly strong taste without greenness), reddish-yellow liquor, dark black wet leaves. Aged tea has a sweet taste.