Grapeseed OilGrapeseed oil is a lightweight, moisturizing oil that is a good additive to soap in small quantities. It doesn't have a long shelf life, so unless you treat it with rosemary oleoresin extract, or have a very low superfat percentage, don't use it more than about 5% in your recipe. Grapeseed oil is lovely in lotions, shaving oils, bath oils, and especially massage oils as it absorbs well without a really greasy afterfeeling.
Hazelnut OilHazelnut oil is an excellent moisturizer in lotions and creams, but has a short shelf life (3-4 months). If you want to add it to soap, I wouldn't recommend using more than about 5-10% in your recipe because of the short shelf life...and I'd add some rosemary oleoresin extract to either the oil or the batch to help the soap from developing DOS or going rancid. Don't get me wrong...it's a lovely oil...just a fairly fragile one. It's also wonderful in lip balms and bath bombs.
Hemp Seed OilHemp seed oil is a deep, green color with a light, nutty smell. No, it doesn't smell like marijuana, nor does it have any of the affects that marijuana has, but it does indeed come from the seed of the cannabis plant. It's really lovely in lotions and creams and great in soap too. It gives a light, creamy/silky lather. Because of its fatty acid makeup, it has a very short shelf life...less than six months...so it should be refrigerated or even kept in the freezer. Treating it with rosemary oleoresin extract is a good idea to help keep it from oxidizing. It can be used as a luxury healing/moisturizing oil in soap up to 10%-15%.
Jojoba OilJojoba is actually a liquid wax that is very similar to sebum in its chemical composition. It contributes a nice stable lather, has remarkable absorption and moisturizing qualities and unlike some of the other luxury moisturizing oils, has a very long shelf life - 1-2 years! Use it at 5-10% maximum. Or just save it for "leave-on" applications like balms, massage bars, bath bombs and lotions. It can make the soap batch trace more quickly, so it's not a good oil to add if you're going to do complex coloring or swirls, or are working with a temperamental fragrance or essential oil.
Kukui Nut OilA rich, liquid nut oil that's native to Hawaii, kukui nut oil contributes to a nice, creamy stable lather in the soap, and is nicely moisturizing. Like the other luxury liquid oils, I recommend using it at 5-10% of your recipe for a richer, creamier soap. In lotions, creams, massage bars and balms, it absorbs quickly, conditions skin nicely, and is reputed to help ease acne, eczema and psoriasis.
Lard makes a super-hard, very white bar of soap with a low, creamy, stable lather that is, believe it or not, nicely moisturizing. Before vegetable oils were commonly available, it was one of the main fats (along with beef tallow) that folks used to make soap. If you use animal oils in your soap, then combining lard with some of the other liquid oils like coconut and olive makes a wonderful, well balanced bar of soap - and is really economical. Make sure your lard is fresh and of high quality. Poor or spoiled lard can give a lardy/bacony/greasy scent to your soap. Use it at any percentage in your recipe, but I recommend not much more than 30-40% or so. Cold process laundry soap can be made with 100% lard with a 0% superfat percentage.
Macadamia Nut Oil
Macadamia nut oil is a light oil with a mild nutty odor. It is unique in its fatty acid makeup in that it contains palmitoleic acid - which makes it really easily absorbed into the skin - and is reported to be really great for older skin. It is mostly used in lotions, creams, massage oils, and other skin healing preparations.
Neem OilNeem oil is extracted from the bark of the neem tree. It is growing in popularity as a soap making oil due to its antiseptic, anti-fungal and insect repellent qualities. I know of one soap maker who uses neem oil at about 25% of the recipe and sends it to soldiers in the middle east to repel sand flies. It evidently works very well. It's also great, all by itself (as both an oil and in a soap recipe) for treating skin conditions like athletes foot. The scent of neem is very strong...a sort of green, earthy, nutty smell...and takes some getting used to. But it doesn't come through too strongly in the soap, and blends well with other earthy scents.
Extra virgin and virgin olive oils come from the very first gentle pressing of the olives. The refined, or Grade A oil (generally the best grade for soap) comes from the second pressing, and is lightly refined/filtered. 100% olive oil makes the famous "Castille soap" and "Marseille soap" must contain at least 72% olive oil. Olive oil is generally the #1 oil in most soap makers' recipes - and for good reason. Olive oil soaps are very moisturizing, make hard, white bars of soap (though high % olive oil soaps take a longer time to cure) and are exceptionally mild. But the lather from Castille soap is low and a bit slimy. Most soap makers combine olive oil with other oils to improve the lather.
Olive Oil, Pomace
Pomace grade olive oil is a thick, rich, green grade of olive oil that is obtained by solvent extraction of the fruit and pits of the olives - what's left over after the first several pressings that give the virgin and Grade A oils. It has a very high level of unsaponifiables (the portions of the oil that don't react with the lye to form soap.) This will make your trace time quicker. Like all olive oil, it makes a nice, moisturizing, mild bar of soap, especially when combined with other oils.