YOU MAY KNOW that polar solvents, such as water, are used to remove polar soils, such as salts, from surfaces. You may also know non-polar solvents, like hexane, remove oils and greases. But what about removing mixed residues, made up of both types of soils?
Avoid ‘Mixed Results’ With A Miscible Mixed Solvent
When it comes to removing polar and non-polar soil mixes, you might be tempted to mix polar and non-polar solvents — but that won’t work. The two solvents aren’t miscible (think: vinegar and oil).
Another common approach might be to clean the surface twice, one with a polar solvent and once with a non-polar solvent. That will work, but it involves twice the time and effort.
A better approach is to use a mixed solvent, such as water (dielectric constant 80) and isopropyl alcohol (dielectric constant 18). They are miscible in all proportions, and the mixed solvent is great for removing mixed residues. If the residues have a high content of oils and greases, use a higher proportion of isopropyl alcohol in the mixed solvent.