ROCK SUGAR SYRUP (ĀB-E NABĀT)

Rock sugar, also known as crystal sugar, is made up of relatively large sugar crystals. The process involves creating a supersaturated solution of sugar and water, which is then allowed to crystallize onto a surface suitable for crystal nucleation, such as a string, stick, or plain granulated sugar. For the production of larger rock sugar crystals, the water is heated before adding the sugar, allowing more sugar to dissolve.

 
Recipes:
Rock sugar, as well as Egyptian rock-sugar solution (āb-e nabāt-e meṣri), is recommended as a sizing material in certain Persian historical treatises, including Resaleh-ye Joharrieh (837 AH/1433 A.D.) and Resāle dar Bayān-e Tariqe-ye Sāḵtan-e Morakkab va Kāḡaḏ-e Alvān (10th A.H./16th A.D.). These sources provide descriptions of rock sugar alongside various other sizing materials.

Simi’s recipe in Resaleh-ye Joharrieh (837 AH/1433 A.D.) explains the process as follows:

و کاغذی که بسیار تنک و پرزناک بود و قلم کاتب را بوقت سرعت کتابت مانع باشد، تدبیر آن است که به آب خربزه شیرین یا به آب نبات مصری یا به آبِ مورد و یا لعاب اسپغول یا حلیم برنج بی روغن و به چند چیز دیگر که مجموع مقوی کاغذ است، کاغذ تنک را قوی توان ساخت و پرزها که بر وی باشد و قلم کاتب را مانع و دافع سرعت حرکت شود بصلاح آرد

The paper that is thin and fluffy and prevents the reed pen from moving smoothly on it [during writing] can be fixed by sizing [paper] with either sweet melon juice, Egyptian rock sugar, or mucilage from myrtle seeds, fleawort seeds, or oil-free rice paste, along with some other sizing agents that strengthen the paper. This process makes the thin paper more resistant, and any protuberances can be ironed out, allowing the reed pen of the calligrapher to move smoothly across the paper as it should.

The second source in 16th century explains the process as follows:

دیگر کاغذی که دارای رنگ پیروزه ناک باشد و مانع قلم باشد، تدبیر آن است که به آب خربزه شیرین یا به آب نبات مصری یا به آبِ مورد و با لعاب اسفیقول و لعاب برنج بی روغن [بگذارد که] مجموع مقوی کاعذ است، و چون کاغذ مهره زند مثلِ آینه نماید

The paper that is of a turquoise color and hinders the pen from moving smoothly on it [during writing] can be treated by sizing [the paper] with sweet melon juice, Egyptian rock sugar, or mucilage from myrtle seeds combined with mucilage from psyllium seeds and oil-free cooked rice mucilage. All these materials contribute to strengthening the paper. When burnished, it becomes smooth, resembling a mirror.