Control salt grain size by how fast crystals form: slow, quiet evaporation of strong, clean brine grows coarse crystals, while rapid boiling, stirring or drying a thick slurry on a hot pan makes fine grains. Coarse salt suits curing, brining and cheese because it dissolves steadily and cakes less, fine salt suits the table and cooking, and since the same weight takes a different volume at each grain size, always weigh salt rather than measure it by the spoonful.
Part of Salt Production & Sourcing
Grain size control is the shaping of salt crystal size through the way brine is evaporated and handled, matched to the use the salt will be put to.
Crystal Size Follows The Rate
Crystals grow from brine that is more concentrated than it can hold (supersaturated). If the brine becomes supersaturated slowly, a few crystals form and grow large. If it becomes supersaturated quickly, many small crystals form at once. The practical consequences:
- Large, coarse crystals: a quiet, slow evaporation of clean brine, as in the last solar pond or a low-heat finishing pan (Solar evaporation ponds). Avoid stirring the crystallising brine.
- Fine grains: hard boiling, stirring, scraping the pan while it is still wet, and evaporating the last of the liquid on a hot base all produce small crystals.
- Floating flakes: crystals that form at the surface of a hot, still brine can grow as flat flakes and float. They are a feature of some finishing pans rather than a defect.
Impurities also matter: some dissolved salts and organic matter disturb crystal growth and give a fine, irregular product (Removing impurities and bitter minerals).
Which Grain For Which Job
- Curing, brining and pickling: coarse, clean salt. It dissolves steadily, rubs on easily, and gives a controlled supply of salt to the meat.
- Cheese and fermentation: pure, free of additives; either size, weighed.
- Table and cooking: fine salt dissolves quickly. Fine salt cakes more readily in humid air.
- Hides and livestock: coarse, rough salt is enough.
Weigh, Don’t Scoop
A teaspoon, cup or scoop of fine salt holds more salt by weight than the same measure of coarse salt, because the smaller grains pack more tightly. The difference is material, and a cure or brine specified by volume will be wrong whenever you change grains. This is the reason the cure ratios in this branch are given by weight (Dry cure ratios and rub formulas). Weigh the salt, and when you must measure by volume, weigh a full scoop of the grade you actually use and note it on the container.
What You Need
- Strong, clean brine, purified if possible
- A way to control the rate of evaporation: pan heat, shade or pond depth
- Sieves of cloth or woven wicker to sort grains
- A scale
Method: Make A Coarse And A Fine Grade
Step 1 (coarse): Finish evaporation at low heat or in a shallow pond, without stirring, and let the crystals grow to a good size before raking.
Step 2 (fine): For fine salt, finish by stirring and evaporating the last liquid, or grind the dried coarse salt on a clean stone (Purification & Grading covers the sorting).
Step 3: Sieve into grades and label each.
Step 4: Dry thoroughly before storing (Keeping salt dry).
Common Mistakes
- Stirring the finishing pan and getting a fine, caked product.
- Using fine salt for a cure specified in weight of coarse salt by volume.
- Grinding salt on a stone that is not food-safe.
Safety
Hot brine and dust
Raking and stirring a hot pan of thick brine scalds; ground salt dust irritates eyes and lungs. Wear a cloth over the mouth and nose when grinding, and use only a clean, food-safe stone or mill.
What’s Next
- Learn next: Iodine and mineral supplementation — what salt lacks that people and animals need
- Combine with: Salt Curing & Brining — where coarse salt does its work