If you want a white base, it's best to use coconut oil and or any other light coloured oil. I love olive oil, but the base colour is too earthy to achieve vibrant colours and unless I want a provincial looking soap, I won't use it. Soaps need to be designed. Have an idea in mind of what you want your final product to look and smell like. Since fragrance oils also interfere with your formula. Factor your fragrance oil in as part of the percentage of your oils so that your lye weight is exacting for the amount of oils in your batch. Be aware that any other ingredient that you add into your batch has ultimately changed your formula to either a) have it trace too quickly b) not produce enough lather. This is also why it's best to use filtered or distilled water. The mineral content in your water will also have an influence on how your soap performs. If you use light coloured oils, then you need less titanium dioxide and that means more lather. For a 800 gram batch of soap made with coconut oil and 10% castor, I will only use half teaspoon of titanium dioxide powder. Anything more will accelerate trace and although castor oil sustains bubbles, don't use too much of it because that too affects trace and also the hardness of the bar. Coconut oil also brings out the best in your fragrances making everything smell sharper. Remember it's better to have less mica or mineral pigments in your soap since these influence both the feel and the soapiness of the product. Coconut oil is more expensive than other oils, but you end up with a better quality product at the end of it. You can do more with your batch and you end up with a Whiter, harder, better lather and sharper fragrance. Unless you want a Provence looking soap. Then use olive oil but still not too much titanium dioxide. You need lots of titanium dioxide to colour olive oil. Provence soaps are cream coloured rather than white anyway. And they are coloured with clays and vegetable dyes rather than mica. Good luck. There is so much trial and error involved since you also have to ultimately come up with a formula that fits in with the pace you like to work at.I,m thinking about using titanium dioxide to make white soap( cp). Has anyone used this and how much to use?