Animal Fats

Part of Soap Making

Rendering, purifying, and selecting animal fats for soap production — the foundation of traditional soap making.

Why This Matters

For most of human history, soap was made from two things: animal fat and wood ash lye. The fat is the core ingredient — it reacts with the alkali in lye to produce soap through saponification. Without properly rendered, clean fat, you get a foul-smelling, grainy, ineffective product that nobody wants to use. With well-rendered fat, you get a hard, white bar of soap that cleans effectively and lasts.

In a rebuilding scenario, animal fats are almost certainly your primary soap-making feedstock. Every animal butchered for food produces fat trimmings that would otherwise be wasted. A single beef carcass yields 10-20 kg of usable fat — enough for months of soap production for a small community. Pigs, sheep, goats, and even poultry produce useful soap-making fats.

Rendering fat is also a preservation technique. Raw fat goes rancid within days in warm weather, but properly rendered tallow or lard keeps for months or even years when stored correctly. This means you can stockpile fat during slaughter season and produce soap year-round.

Understanding Animal Fats

Fat Types and Their Properties

Fat Source	Name	Melting Point	Soap Quality	Hardness
Beef/cattle	Tallow	42-48C	Excellent — hard, white bar	Very hard
Sheep/mutton	Mutton tallow	44-50C	Very good — hard bar	Hard
Pig	Lard	36-42C	Good — softer bar	Medium
Goat	Goat tallow	40-46C	Good	Hard
Poultry (chicken, duck)	Schmaltz	30-35C	Fair — soft bar	Soft
Bear	Bear grease	28-35C	Good — conditioning	Soft

Best for beginners

Start with beef tallow. It produces the hardest, whitest, most forgiving soap bars. Tallow soap was the standard commercial soap for centuries.

Where to Find Fat on an Animal

Beef/cattle:

• Suet: The hard fat surrounding the kidneys and loin. Highest quality for soap — produces the whitest, hardest tallow.
• Caul fat: The lacy membrane of fat around internal organs. Easy to render.
• Trim fat: Fat trimmed from muscles during butchering. Good quality but may contain meat fragments.
• Back fat: Subcutaneous fat layer. Moderate quality.

Pigs:

• Leaf lard: Fat around the kidneys. Highest quality, renders very clean.
• Back fat: The thick subcutaneous layer. Good quality, high yield.
• Belly fat: Mixed with meat — render carefully to separate.

Sheep:

• Kidney fat: Best quality, similar to beef suet.
• Tail fat (fat-tailed breeds): Large volume, moderate quality.
• Trim fat: Good for soap, may have strong odor if not rendered well.

The Rendering Process

Rendering transforms raw fat into clean, stable tallow or lard by melting it, separating the pure fat from connective tissue, water, and protein.

Preparation

1. Collect all fat trimmings immediately after butchering
2. Remove as much meat, blood, and membrane as possible — these cause rancidity and odor
3. Cut or chop the fat into small pieces (1-2 cm cubes) — smaller pieces render faster
4. If possible, grind the fat (use a meat grinder or chop very finely)

Wet Rendering (Recommended for Beginners)

The safest method with the cleanest results.

1. Place chopped fat in a large pot
2. Add water to cover the fat by 2-3 cm
3. Heat slowly to a gentle simmer — do NOT boil vigorously
4. Stir occasionally to prevent sticking
5. Maintain a gentle simmer for 2-4 hours (longer for larger batches)
6. The fat melts out of the connective tissue and floats on the water
7. Proteins and impurities dissolve in the water or sink to the bottom
8. When the fat pieces have shrunk to small, crispy bits (cracklings), rendering is complete
9. Remove from heat and let cool slightly
10. Strain through a cloth-lined sieve into a clean container
11. Let cool completely — the tallow solidifies on top of the water
12. Lift off the solid tallow disc and scrape any residue from the bottom surface
13. The water underneath contains dissolved impurities — discard it

Dry Rendering

Faster but requires more attention to prevent burning.

1. Place chopped fat in a heavy pot or pan
2. Heat over low to medium heat — no water added
3. Stir frequently to prevent burning
4. The fat melts out gradually; remaining tissue pieces (cracklings) turn golden and crispy
5. When cracklings are golden-brown and floating, rendering is complete
6. Strain through cloth into a clean container
7. This method produces a slightly more colored and flavored fat than wet rendering

Temperature control

Fat burns easily above 200C, producing acrid smoke and off-flavors. Keep the heat low and stir frequently. If the fat starts smoking, remove from heat immediately.

Double Rendering (Highest Quality)

For the whitest, purest tallow suitable for fine soap:

1. Complete a wet rendering as described above
2. Melt the solidified tallow again in fresh water
3. Bring to a gentle simmer for 30-60 minutes
4. Cool and solidify again
5. Lift off and scrape
6. Repeat a third time if the tallow is still yellowish or has an odor
7. Each re-rendering removes more impurities, producing progressively whiter, more neutral-smelling fat

Purification Techniques

Salt Washing

Salt draws out remaining proteins and water-soluble impurities:

1. Melt rendered tallow in a pot of water
2. Add 1 tablespoon of salt per liter of water
3. Stir well and bring to a gentle simmer for 30 minutes
4. Cool and allow the tallow to solidify on top
5. Lift off and scrape the bottom surface clean
6. The salt water carries away dissolved proteins and minerals

Bleaching

To whiten yellowish tallow:

1. Melt tallow and add water as above
2. Add a small amount of wood ash (2-3 tablespoons per kg of tallow) — the alkali in the ash bleaches the fat
3. Simmer gently for 1 hour
4. Cool, solidify, and lift off
5. The tallow will be noticeably lighter in color

Deodorizing

If your tallow has a strong animal smell, simmer it with a handful of salt and a few pieces of charcoal (activated charcoal is best, but regular hardwood charcoal works). The charcoal absorbs odor compounds. Strain through cloth to remove charcoal.

Testing Fat Quality

Purity Test

Break a piece of solid tallow:

• Good: Snaps cleanly with a waxy fracture surface. White to cream colored. Mild or no smell.
• Fair: Bends slightly before breaking. Yellowish. Mild animal smell. Will make acceptable soap.
• Poor: Soft, greasy, strong smell. Needs re-rendering or additional purification.

Iodine Value (Simplified)

This determines how hard or soft the soap will be:

• Drop a small piece of tallow into warm water (50C). Pure tallow remains solid — it has a high melting point and produces hard soap.
• If it softens or melts, the fat has a lower melting point (more unsaturated) and will produce softer soap.
• Blend softer fats with harder fats for a balanced bar.

Rancidity Check

Smell the fat. Fresh, well-rendered tallow smells neutral or mildly waxy. Rancid fat smells sharp, sour, or like old paint. Mildly rancid fat can still be used for soap (the saponification process neutralizes some rancidity) but produces a less pleasant-smelling bar.

Storage

Short-Term (Weeks to Months)

1. Store rendered tallow in a cool, dark place in a sealed container
2. Below 15C, tallow keeps for 3-6 months without treatment
3. Keep away from light and heat, which accelerate rancidity

Long-Term (Months to Years)

1. Salt preservation: Mix 1-2% salt by weight into melted tallow before solidifying
2. Cool storage: Below 5C (a root cellar or cold spring), tallow keeps for 1-2 years
3. Water-sealed: Submerge solid tallow blocks in salted water in a sealed crock
4. Vacuum-like storage: Fill a container completely with melted tallow, leaving no air space. Once solidified, the absence of air prevents oxidation

Signs of Spoilage

Sign	Severity	Action
Slight yellowing	Normal	Use normally
Surface oxidation (darker outer layer)	Minor	Trim and discard outer layer, use the rest
Sour or sharp smell	Moderate	Re-render with salt and charcoal, or use for utility soap only
Mold on surface	Moderate	Scrape off mold, melt and re-render
Strongly rancid, dark throughout	Severe	Discard or use only for industrial soap (cleaning tools, not skin)

Fat Blending for Better Soap

Different fats produce soaps with different properties. Blending gives you the best of each:

Fat	Contributes To Soap
Beef tallow	Hardness, long-lasting bar, stable lather
Lard (pig)	Smooth texture, moisturizing, creamy lather
Goat tallow	Similar to beef but slightly softer
Poultry fat	Conditioning, but too soft alone

Recommended Blends

All-purpose bar: 80% beef tallow + 20% lard. Hard, long-lasting, smooth.

Gentle skin bar: 60% tallow + 30% lard + 10% poultry fat. Softer, more moisturizing.

Heavy-duty cleaning: 100% beef tallow. Maximum hardness and cleaning power.

When plant oils are available: Replace 10-20% of the animal fat with coconut oil (excellent lather) or olive oil (moisturizing) for a superior bar.

Yield Calculations

Input	Approximate Tallow Yield
1 kg raw beef fat	700-800 g rendered tallow
1 beef kidney suet	2-4 kg tallow
1 whole beef carcass fat trim	10-20 kg tallow
1 whole hog fat trim	5-10 kg lard
1 sheep carcass fat trim	2-4 kg tallow

Soap Yield from Fat

Using standard cold-process soap ratios:

• 1 kg of tallow produces approximately 1.3-1.5 kg of soap (the lye and water add weight)
• A 100-gram bar of soap lasts one person approximately 2-4 weeks with daily use
• A community of 50 people needs approximately 25-50 kg of soap per month
• This requires 17-35 kg of tallow per month — achievable from regular livestock slaughter

Every scrap of fat from butchering is potential soap. In a rebuilding world, waste fat is not waste — it is the raw material for hygiene, one of the most important factors in community health and disease prevention.