Surface Tension of a Solvent & Results

MicroCare precision cleaners are the best choice in the industry for cleaning difficult shapes and awkward pieces. The reason for this success is the very low surface tension these products exhibit.

Surface tension is the cohesive behavior of a liquid in which the molecules of the liquid are more attracted to each other than to the surfaces around it. This is an “attractive force” and is exerted upon the surface molecules of a liquid by the molecules beneath the surface. The behavior we all see and know is when the liquid forms itself into a shape having the smallest surface area.

High surface tension liquids, like water, form three-dimensional balls or bubbles, as in the photo on the right. Low surface tension materials spread out, flowing across a surface and exhibit very little three-dimensional height.

Water droplets on a plants leaf are a good demonstration of the surface tension of water

We experience surface tension is a thousand ways, every day. Every time we wash the dishes or take a shower, we add soap to the water to lower the surface tension of the water so that it more readily soaks into pores and soiled areas. The water strider is an insect which can walk on the surface of water because their weight is not enough to penetrate the surface. Many camping tents are somewhat rainproof in that the surface tension of water will bridge the pores in the finely woven material. But if you touch the tent material with your finger, you break the surface tension and the rain will drip through. And, interestingly, cold water has more surface tension than hot water, which is why hot water cleans better than cold water.

Surface Tension Affects Precision Cleaning

When it comes to precision cleaning, especially in a vapor degreaser, cleaning fluids with lower surface tension will out-perform high-surface tension fluids. Lower surface tension means the cleaning fluid can get into tight spaces easily. It directly affects the ability of the cleaning fluid to wet a surface, and obviously you can’t clean if you can’t wet.

Here’s how the numbers compare:

Not-In-Kind Benchmarks

Brand Name or Description	Principle Supplier	Base Chemistry	Surface Tension (dyne/cm)
Water	<Many>	H20	73
IPA Alcohol*	<Many>	Alcohol	22

First Generation

Brand Name or Description	Principle Supplier	Base Chemistry	Surface Tension (dyne/cm)
Trichloroethylene (TCE )	<Many>	Chlorine	29
Perchloroethylene (PCE or Perc)	<Many>	Chlorine	35
Freon™ TF†	DuPont	CFC-113	17

Second Generation

Brand Name or Description	Principle Supplier	Base Chemistry	Surface Tension (dyne/cm)
Genesolv® 2004†	Allied-Signal	HCFC-141b	19
AK-225†	Asahi	HCFC-225	16
n-Propyl BRomide (nPB)	<Many>	Bromine	26

Third Generation

Brand Name or Description	Principle Supplier	Base Chemistry	Surface Tension (dyne/cm)
Novec® 71DA	3M	HFE-7100	16
Vertrel™ XF	Chemours	HFC-43-10	14
MicroCare™ HDS	MicroCare	HFC-365	19
Vertrel™ SFR	Chemours	Trans	20

Fourth Generation

Brand Name or Description	Principle Supplier	Base Chemistry	Surface Tension (dyne/cm)
Opteon™ Sion/SF79	Chemours	MPHE	21
Solstice® PF	Honeywell	HFO-1233zd	13
AE-3000	Asahi	HFE-347pc-f	16

Tergo™ Generation

Brand Name or Description	Principle Supplier	Base Chemistry	Surface Tension (dyne/cm)
Tergo™ Metal	MicroCare	HFO-110	21
Tergo™ CFCF Rinse	MicroCare	HFO-110	14
Tergo™ High Perf. Flux Remover	MicroCare	HFO-110	19

Disclaimer

* Indicates a flammable cleaning fluid; this usually is an ingredient in an azeotropic blend.

† Indicates a Class 1 or Class 2 ozone-depleting solvent; no longer used by environmentally responsible companies and countries; included here merely for completeness.

A higher surface tension means the product will deliver better cleaning.

So here’s the short answer you were probably looking for: when it comes to tough cleaning problems, modern, nonflammable cleaning fluids are a far better choice than old-style aqueous cleaners. The modern cleaning fluids have less environmental baggage than the old-style solvents and are great replacements for ozone-depleting solvents such as HCFC-225, toxic solvents such as TCE and the high-global-warming solvents such as perfluorocarbons (PFCs).