Hey,
Varying the contact angle definitely affects the distance travelled by the ethanol but does not affect the perpendicular height. The only thing you need to take into account is that in this case, use the perpendicular height as the actual height not the distance travelled by ethanol.
To cut...
Hi,
If you say white spirit you mean Ethanol right, I suppose Propan-1-ol is a better solvent than ethanol the only problem is that it is hygroscopic, so better handle carefully.
If you are not satisfied with my answer, Can you put your question in a better way giving chemical names if possible.
Adjusting pH will just introdue unecessary reactions which definitely have side effects (heat of reaction, incomplete reactions, precipitates coating etc), why don't you just use a corrossion resistant centrifuge e.g. stainless steel.
