Brine Strength

Part of Food Preservation

Without a scale or measuring cups, how do you know your brine is strong enough to preserve food? The egg float test — a method used for centuries before laboratory instruments existed — gives you a reliable answer in seconds.

Why Concentration Matters

Brine that is too weak is worse than no brine at all. Sub-10% salt solutions create a warm, moist, nutrient-rich environment that accelerates bacterial growth instead of preventing it. You have created a bacterial incubator and placed your food inside it.

Brine that is too strong wastes salt — a precious resource in a post-collapse world — and produces food so aggressively salty that it requires extensive desalting before eating.

The goal is to hit the sweet spot: strong enough to reliably kill or suppress all dangerous bacteria, weak enough to not waste salt. For most preservation, that means 10-20% salt by weight.

The Egg Float Test

This is the definitive low-tech method for measuring brine concentration. It requires one thing: a raw egg in its shell.

How It Works

A raw egg has a specific gravity (density) of approximately 1.03-1.09 depending on freshness. Fresh water has a density of 1.00. A raw egg sinks in fresh water.

As you add salt to water, the density of the solution increases. At approximately:

Salt Concentration	Density	Egg Behavior
0% (fresh water)	1.000	Sinks to bottom, lies flat
3-5%	1.02-1.04	Sinks slowly, may tilt
8-10%	1.06-1.07	Hovers mid-water, barely rises
10-12%	1.07-1.09	Floats with just the tip breaking the surface
15%	1.10	Floats with a quarter-sized patch of shell above the surface
20%	1.15	Floats high — a silver-dollar-sized area exposed
26% (saturated)	1.20	Bobs on the surface like a cork

The Test

1. Mix your brine — dissolve salt into water until you think you have enough
2. Drop a raw egg (uncracked, in its shell) into the brine
3. Read the result:

• Egg sinks and stays on the bottom: brine is below 8%. Too weak for any preservation. Add more salt
• Egg floats just off the bottom, hovers mid-water: approximately 10%. Minimum threshold for short-term preservation of thin cuts only
• Egg floats with a small circle of shell visible above the surface (about the size of a coin): approximately 12-15%. This is your target for standard preservation brine. The exposed area should be roughly the size of a US quarter (1 inch / 2.5 cm diameter)
• Egg floats high, large area exposed: above 18%. Strong brine — good for heavy-duty long-term preservation and the brine barrel method
• Egg bobs on the surface, nearly half exposed: saturated or near-saturated (24-26%). Maximum concentration — salt is no longer dissolving. Use for the standing brine barrel method

Use a Fresh Egg

As eggs age, the air cell inside grows larger, making old eggs more buoyant. An old egg will float in weaker brine than a fresh egg, giving you a falsely optimistic reading. Use the freshest egg available. If only old eggs are available, the egg will float at a lower concentration than listed above — compensate by adding extra salt until the egg rides noticeably higher than “just floating.”

Calibration Without an Egg

If you have no eggs, these substitutes work with different calibration points:

Object	Floats At Approximately	Notes
Raw potato (small, whole)	10-12%	Peel it first for more consistent results
Apple (small, unpeeled)	5-8%	Too buoyant to test high concentrations
Raw beet (peeled)	10-12%	Similar density to potato
Dry hardwood chip (oak, maple)	N/A	Floats in fresh water — useless
Small stone or pebble	Never floats	Too dense — useless

The potato is the best egg substitute. A peeled raw potato that floats to the surface and exposes a coin-sized area indicates approximately 12-15% brine — the same target as the egg test.

Measuring By Taste

Experienced salt curers can gauge brine strength by taste. This is less precise than the float test but useful as a quick check:

• Pleasantly salty (like well-seasoned soup): 3-5%. Too weak for preservation
• Noticeably salty (uncomfortable to drink more than a sip): 8-10%. Borderline
• Aggressively salty (lips pucker, mouth dries, urge to spit): 15-18%. Good preservation range
• Painfully salty (burning sensation, unable to swallow): 20%+. Heavy-duty brine

Taste testing works well as a supplement to the float test, not a replacement. Taste perception varies between people and changes with dehydration, diet, and habituation.

Adjusting Brine Strength

Strengthening Weak Brine

If the egg sinks or barely hovers:

1. Add salt gradually, stirring after each addition until fully dissolved
2. Re-test with the egg after each addition
3. Warming the brine helps dissolve salt faster (salt solubility increases with temperature)
4. If the salt won’t dissolve (crystals sit on the bottom despite stirring), the water may be near saturation at that temperature — warm it up

Weakening Overly Strong Brine

If the egg floats too high and you’re wasting salt:

1. Add water gradually, stirring between additions
2. Re-test with the egg
3. Save the displaced brine rather than discarding it — you can use it later

Monitoring During Curing

Brine weakens over time as meat releases moisture into the solution. For cures lasting more than 5-7 days:

1. Re-test with the egg weekly
2. If the egg drops lower than the initial test, add salt until it returns to the target float level
3. For long cures (2+ weeks), replace the brine entirely with fresh solution at the original concentration. The old brine has absorbed blood, proteins, and dissolved fats that also reduce its effectiveness

The Salinometer: If You Find One

A salinometer (also called a salometer or brine hydrometer) is a glass float with a weighted bottom and a graduated scale. It works on the same density principle as the egg test but gives a precise numerical reading.

If you salvage one from a laboratory, food processing facility, water treatment plant, or swimming pool supply store, it will read in degrees (0-100 scale where 100 = fully saturated at 26.3% salt):

Salinometer Reading	Salt %	Equivalent Egg Float
30-40°	8-10%	Barely floats
50-60°	13-16%	Coin-sized exposure
70-80°	18-21%	Large area exposed
90-100°	24-26%	Bobs on surface

Target for standard preservation: 55-65° on the salinometer (14-17% salt).

Quick Reference: Brine Strength by Application

Application	Target %	Egg Float Description	Salt per Gallon
Vegetable fermentation	3-5%	Egg sinks	1/2 cup (4 oz)
Flavor brine (poultry)	5-8%	Egg barely lifts off bottom	3/4 cup (6 oz)
Minimum preservation	10%	Egg hovers mid-water	1.5 cups (12 oz)
Standard preservation	15%	Egg floats, coin-sized exposure	2.5 cups (20 oz)
Heavy preservation	20%	Egg floats high	3 cups (24 oz)
Saturated (barrel method)	26%	Egg bobs like a cork	3.5 cups (28 oz)

Key Takeaways

• The egg float test is the most reliable low-tech method for measuring brine strength — a raw egg floating with a coin-sized patch exposed means approximately 15%, which is the standard preservation target
• Never use brine below 10% for meat preservation — weak brine accelerates bacterial growth rather than preventing it
• Re-test brine weekly during long cures, as meat moisture dilutes the solution over time
• A peeled raw potato works as a substitute if no eggs are available — it floats at roughly the same concentration as an egg
• Taste-testing supplements the float test: if the brine doesn’t make you wince, it’s probably too weak for preservation