lye table

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the "table" below lists [many of] the oils used in soap making. in addition to lye factors for sodium hydroxide and potassium hydroxide, it gives each oil's sap value, the quality it imparts to the resulting soap (e.g. lather volume and stability, and emollient properties), and its ins and iodine values.
-- see "oil properties" for a chart listing the oils with their component fatty acids.
-- see "oils & butters" for a list [of those most commonly used] with their descriptions, characteristics, and benefits.
-- see the "soap calculator" for determining lye and water requirements and analyzing soap formulas.
naoh (sodium hydroxide) is used for bar soap; koh (potassium hydroxide) is used for liquid soap. the figures [in the table] for the *naoh and koh factors represent a zero discount. to assure that all the lye is being consumed in the saponification process, it's a good practice to discount these amounts, say 7% - 8%. this is a safe range since the sap for a given oil varies from batch to batch and the lye factors, (derived from this value), varies from calculator to calculator ...the various calculators are using the same formula, they're just using different sap values. never discount below five percent since the sap you're using (from whatever source) is most likely a generalizations, and you don't know the actual sap value(s) of the actual oil(s) you're using.
when planning a recipe, there are three factors that should be considered in selecting how much and of which oils are chosen. two these are the ins and the iodine values. an oil's ins value is based on its sap and iodine values, and a soap's ins is the weighted average of the ins values of the oils used to make it. the ins values are used to determine if your oils are balanced. the iodine values are used to insure the hardness of your soap.
the concept of ins values comes from dr. robert mcdaniel's book, "essentially soap". in brief, the ins values are used to determine the balance of the combination of oils used in a particular soap formula. it is suggested that you should aim for an ins value of about 160. this is just a guage of how balanced your oils are: the higher the number (above 160), the harder the bar with more lather and will tend be more drying; the lower (below 160), the softer the bar with less lather and will tend to be more moisturizing. so, if your figures are way above or below 160, you may want to adjust the recipe.
note that this is just a guage and is not written in stone. ins values (just as sap values) vary ...sometimes greatly ...from source to source. beside, there are many great recipes that don't conform to this analysis and yet produce great soap. in the end, it's your decision based on your objective and your experience.
the iodine value is an expression of the degree of unsaturation of a fat measured by determining the amount of iodine which will react with a natural or processed fat under prescribed conditions. the iodine value test is used only in the laboratory; commercial fats do not contain iodine. the iodine value is an indication of the soap's hardness based on the oils used. iodine values are typically listed as a range, however, for the purpose of calculations, use the average. you should aim for an iodine value of less than 55. the lower the value, the harder the bar.
the third factor (which may need to be considered) is the maximum usage. certain oils have a maximum, beyond which they [could] impart unwanted qualities to the soap. case in point is coconut oil, which is used in many recipes for its lathering qualities and to add hardness to the soap. however, if it constitutes more than 25% - 30% of the total oils, it has a drying effect. the "max" column displays these maximums where applicable (and the information was available). where a figure or range stands alone, this is a usage recommendation. where this figure is preceded by "<", this is the maximum amount you should use. note: the usage recomendations and maximums expressed in this table refer to cp/hp bar soap. they may not apply to other soap type, (e.g. liquid, cream, whipped, transparent).
for the sake of consistency, all the sap values were obtained from one source, the "mms lye calculator". likewise, all the iodine values (with the noted exceptions) were obtained from one source, "kathy miller's soap pages". those exception are avocado butter, beeswax, evening primrose oil, kokum butter, lanolin, neem tree oil, peanut oil, shea oil, stearic acid, and walnut oil, whose iodine values weren't listed on the chart and were obtained elsewhere.

oilsapnaoh *
koh *
max %
of oils
almond (sweet) oil193.5.1379.1935stableultra high9793-106<6
apricot kernel oil190.0.1354.1900stableultra high9192-1086-12
avocado butter195.0.1390.1950stableultra high12060-903-30
avocado oil187.5.1337.1875stableultra high9980-953-30
canola oil192.0.1369.1920lightlight56105-120<50
castor oil180.3.1285.1803highmoderate9582-903-30
cocoa butter191.5.1365.1915stableultra high15733-42<15
coconut oil258.0.1839.2580highmoderate258<10<25-30
corn oil190.0.1354.1900lightmoderate69103-130<100
cottonseed oil194.0.1383.1940stablehigh89103-116<25
emu oil192.0.1369.1920stableultra high1287510-20
evening primrose oil190.0.1354.1900lightultra high40135-1651 tsp/lb
flaxseed (linseed) oil191.5.1365.1915lightlight-6105-115---
grapeseed oil187.0.1333.1870lightmoderate66125-1423-6
hazelnut oil193.0.1379.1935lighthigh9790-103<20
hempseed oil192.8.1374.1928lightmoderate39166.56-25
jojoba oil092.5.0659.0925noneultra high1180-856-12
kokum butter190.0.1354.1900stablemoderate15432-402-5
kukui nut oil192.0.1369.1920lightmoderate24155-17510-20
lard (pork)194.6.1387.1946stablemoderate13943-45<70
macadamia nut oil195.0.1390.1950lightmoderate11973-79<6
mango butter187.8.1339.1878lightultra high12855-655-15
neem tree oil199.0.1419.1990lightultra high12484-94<40
olive oil190.0.1354.1900stableultra high10979-95<100
palm oil199.1.1419.1991stablehigh14545-5720-40
palm kernel oil237.5.1693.2375highhigh18337<25-30
peanut oil190.0.1354.1900lightmoderate9993<20
safflower oil190.0.1354.1900lightmoderate4786-119<20
sesame oil193.0.1376.1930lightmoderate81105-1153-10
shea butter180.0.1283.1800lightultra high11655-712-5
shea oil182.0.1297.1820lightultra high9975-902-5
soybean oil (liquid)190.0.1354.1900lightlight61124-132<20
stearic acid206.0.1469.2060lighthigh2042---
sunflower oil (hi-oleic)191.5.1365.1915lighthigh6385<15
tallow (beef)197.0.1404.1970stablemoderate14743-45<100
walnut oil190.0.1354.1900lightmoderate45140-150---
wheat germ oil187.5.1337.1875lightultra high58125-135<6

fyi: the formula to calculate the lye factor(s) is simple. first you take the sap value, which represents the amount of potasium hydroxide (express in milligrams) that it'll take to saponify one gram of that particular oil, and divide it by 1000. that's your koh factor. now divide that by 1.40275, which is the difference between the amount of sodium hydroxide and potassium hydroxide needed to saponify the same amout of a particular oil -- (many calculators and tables just round off to 1.4). the result is the naoh factor.
the [estimated] ins value is calculated by subtracting the iodine value from the sap value. since [most of] the iodine values are ranges, the average (the midpoint between the two amounts) is used. both the sap value and the iodine range for any particular oil may vary from source to source, so the ins value may also differ. but, (as with the sap and iodine values), it should be in the same range.
‡ the concept of ins values is borrowed from dr. robert mcdaniel's book, "essentially soap." he in turn borrowed it from an unattributed source. where available, the ins values furnished by "dr. bob" (shown in red) are used instead of the "estimated" calculations.
the ins and iodine values for your soap are computed in pretty much the same way as the lye is calculated. however, instead of using the oil's quantity (as in the lye calculation), you use the oil's percentage of the total oils. multiply that times the ins or iodine value for that oil. add them all together and you get the ins or idodine value for the soap. the total ins should be around 160; the total iodine should be 55 or below.