Lard vs vegetable shortening in soap
Shortening stands in for lard in the kitchen, but in soap it makes the softer bar: 26 for hardness on its own against lard’s 42, with 27.8 % linoleic acid against 8 %, the acid that shortens a bar’s shelf life. These figures are the USDA’s for the older, partially hydrogenated shortening; today’s carries more polyunsaturated fat still, so it makes a softer bar that goes rancid sooner. No saponification value is published for it, and the one the calculator works out from its fatty acids is 2.5 % below lard’s.
Lard (pure rendered pork fat) Vegetable Shortening (US household, partially hydrogenated) Compare them with other oils
The published figures
| Lard | Vegetable shortening | |
|---|---|---|
| Saponification value, mg KOH/g | 192–203 | not published |
| Used by the calculator, mg KOH/g | 197.5 (midpoint) | 192.6 (derived) |
| SAP for NaOH, g/g | 0.1408 | 0.1373 |
| Iodine value, g I₂/100 g | 55–65 | — |
| INS (SAP − IV) | 138 | — |
| Melting point, °C | — | — |
| Unsaponifiable matter, % | ≤ 1 | — |
| Name on a soap label | Sodium Lardate | — |
Each oil alone
| Lard | Vegetable shortening | Usual range | |
|---|---|---|---|
| Hardness | 42 | 26 | 29–54 |
| Cleansing | 2 | 0 | 12–22 |
| Conditioning | 55 | 73 | 44–69 |
| Bubbly lather | 2 | 0 | 14–46 |
| Creamy lather | 40 | 25 | 16–48 |
A single oil’s hardness, cleansing and the rest are the same sums the calculator shows for a recipe, applied to that one oil. They explain what the oil brings to a blend; they do not predict how a soap of only that oil would feel.
Swapping one for the other
Gram for gram, vegetable shortening takes 2.5 % less lye than lard. For a kilogram of oil at a 5 % superfat, that is 133.8 g of sodium hydroxide for lard and 130.5 g for vegetable shortening.
In the bar below, where it is 35 % of the oils, weigh the lye for one and put in the other without recalculating, and the superfat moves:
| Lye weighed for | Oil used | Superfat |
|---|---|---|
| Lard | Vegetable shortening | 4.2 %recalculate |
| Vegetable shortening | Lard | 5.8 %recalculate |
The superfat is the share of the oils the lye leaves unsaponified, planned here at 5 %; below zero, there is more lye than the oils can take. Put the oil you actually have in the lye calculator and it works out the lye for that oil.
The same bar with either
The bar: 35 % of the one or the other, at a 5 % superfat, for 1,000 g of oils. The rest: 35 % olive oil, 25 % coconut oil, and 5 % castor oil.
| With lard | With vegetable shortening | Usual range | |
|---|---|---|---|
| Sodium hydroxide, g | 141.3 | 140.2 | |
| Hardness | 41 | 35 | 29–54 |
| Cleansing | 18 | 17 | 12–22 |
| Conditioning | 55 | 62 | 44–69 |
| Bubbly lather | 22 | 22 | 14–46 |
| Creamy lather | 27 | 22 | 16–48 |
| Linoleic and linolenic acid, % | 8.6 | 15.7 |
Open the bar with lard Open the bar with vegetable shortening
Fatty-acid profile
| Fatty acid | Lard | Vegetable shortening | |
|---|---|---|---|
| Myristic acid | C14:0 | 1.8 (1–2.5) | 0.2 (0.13–0.21) |
| Palmitic acid | C16:0 | 25.0 (20–30) | 13.2 (12.23–14.53) |
| Palmitoleic acid | C16:1 | 3.0 (2–4) | 0.0 (0–0.08) |
| Stearic acid | C18:0 | 15.0 (8–22) | 12.1 (10.55–12.92) |
| Oleic acid | C18:1 | 45.0 (35–55) | 43.6 |
| Linoleic acid | C18:2 | 8.0 (4–12) | 27.8 |
| α-Linolenic acid | C18:3 n-3 | 1.5 (≤ 1.5) | 2.0 (1.25–2.59) |
| Arachidic acid | C20:0 | 1.0 (≤ 1) | 0.5 (0.27–0.51) |
| Gadoleic acid | C20:1 | 1.5 (≤ 1.5) | 0.1 (0–0.29) |
| Erucic acid | C22:1 | 0.5 (≤ 0.5) | 0.0 |
The figure the calculator uses for each oil, as a percentage of its fatty acids, with the published range in brackets.
Recipes with lard
- Old-fashioned lard bar 80 % of the oils
- Budget lard and canola bar 50 % of the oils
- Soy-free lard and sunflower bar 45 % of the oils
- Oatmeal and honey scrub bar 40 % of the oils
- Citrus kitchen bar 35 % of the oils
- Lavender goat milk bar 35 % of the oils
Guides
Other comparisons
Where these numbers come from
Lard (pure rendered pork fat)
Section 3 GLC fatty-acid ranges (% of total FA) are mandatory; the Appendix table 'Chemical and physical characteristics' (relative density, refractive index, titre, saponification value, iodine value (Wijs), unsaponifiable matter) is ADVISORY. Later editorial amendments (2019+) not checked - FAO site Cloudflare-gated.
JP XVIII 'Lard' (Adeps Suillus): melting point 36-42 C; congealing point of the fatty acids 36-42 C; acid value NMT 2.0; saponification value 195-203; iodine value 46-70.
Vegetable Shortening (US household, partially hydrogenated)
Read from FoodData Central's SR Legacy download (FoodData_Central_sr_legacy_food_csv_2018-04.zip, food_nutrient.csv) because the API's shared demo key was rate-limited that day; g per 100 g, seven analysed samples per acid (derivation code A) with mean, minimum and maximum; total lipid 99.97 g, water 0 g.
Read from the FNDDS download (FoodData_Central_survey_food_json_2024-10-31.zip). Its only input food is SR 04615 'Shortening, vegetable, household, composite' at 100 g per 100 g, so USDA's current survey database still describes shortening with the composite used here.
Cross-check in notes only; older data without derivation codes, 11-19 samples per acid.
Cross-check in notes only; one to three samples per acid.
Ingredients: 'Soybean Oil, Fully Hydrogenated Palm Oil, Palm Oil, Mono And Diglycerides, TBHQ And Citric Acid (Antioxidants).' Per 1 Tbsp (12 g): total fat 12 g, saturated 3.5 g, trans 0 g, polyunsaturated 6 g, monounsaturated 2.5 g. Used only to say what today's product is; no figure from it enters the record's fields.