Ideas For Objective Ways To Measure Cheaply Measure Surface Tension?

[vossad01]

In most cases you can dilute an ink as much as you want with something like Noodler's Blue Ghost and still maintain a usable flow for a fountain pen. The same cannot be said for distilled water.

 

I have a surfactant (Kodak Photo Flo) which I can use to reduce the surface tension thus making the ink wetter or flow better. I want to mix the surfactant with water to achieve a solution that could be used to dilute an ink while still maintaining good/usable flow (similar to how Blue Ghost can be used).

 

The obvious solution is trial and error of mixing concentrations, diluting some inks, and writing with them until I find a surfactant concentration that I feel writes well. However, that is tedious and subjective.

 

Does anyone have ideas on how to do this more efficiently or objectively?

 

Edit: Note: I fail at titles.

Edited July 14, 2014 by vossad01

[oldmatekev]

Measuring the depth of the meniscus in a narrow vessel (like a test tube or bottle neck) will at least give you a relative indication.

If you use the same vessel for each test, the shallower the meniscus the lower the surface tension.

[DavidB]

A single drop (calibrated size) on a cleaned surface (like glass) can also tell you the surface tension of a drop of liquid. The key term here is "contact angle." See this article: https://en.wikipedia.org/wiki/Contact_angle. There's a good diagram, too. Essentially, for a given surface, the "wettability" of the surface is a function of the surface tension of the liquid being put on it. Steel, glass, aluminum, all have different wettability characteristics, and for each, the degree of wettability can be adjusted by adjusting the charcteristics of the liquid on it. More surfactants may increase or decrease the wettability depending on the surface type.

 

The best part, though, is that a good camera with a macro setting for up-close pictures, should do great at capturing the contact angle of the drop on the surface.

 

DavidB