What is a dense/heavy transparant oil or inert/safe non-water-based liquid?
Sorry I’m late to the party. If you want to make a sol, (relative) density is only one of the factors to consider. The liquid viscosity and the particle size are also very important. The physical factors that make soil in liquid dispersions last are a really small solid particle size and high liquid viscosity. Density, as you’ve discovered, is hard to play with. Here’s the relationship you need: rise time ~ (density difference) / (viscosity) * (particle size)^2* There is not much you can do with density, because there isn’t that wide a range of fluid densities, but there is a huge range (5 orders of magnitude) of viscosities to choose from. That’s where you will get you bang for buck. For reference below, water has a density of 1 (in specific gravity units) and a viscosity of near enough 1 cP (mPa.s). Almost all hydrocarbons and common solvents are not going to do what you want not because of density, but because their viscosities
