These tests will help you to determine the ratio of oil to water in a moisturising product.
Apply moisturiser to your skin. If the skin under the moisturiser is warm, there is a greater percentage of oil in the product. If the area is cool, there is a greater percentage of water. The science behind this is that evaporation cools, and water evaporates. Oil does not evaporate and therefore traps heat in the body.
Put a small amount of moisturiser on a tissue, and hold it over a lightbulb. Products with higher oil content will melt. The wider the area of melted oil, the greater the percentage of oil in the moisturiser.
I experimented this with Olay’s Complete UV Protection Moisture Lotion SPF15 for combination/oily skin.
So there you go, a useful beauty tip from the expert herself (I meant Bobbi ).
Another method to check the oil-to-water ratio was a good tip I picked up from Traclyn, who ran an oiliness test of a BB cream on a piece of facial blotter. I think it is another good way to check if the product is going to be too greasy for you, especially if you suffer from oily skin.