368 JOURNAL OF COSMETIC SCIENCE
With the wrapping method the film had an even surface without any holes, however,
once the tablet was wrapped with the film, one side of the tablet had a thicker coating
and during the wrapping process the film could have damaged. Both methods were found
unreliable due to the reasons discussed here. Even the tablets coated or wrapped with the
traditional nail polishes were forming bubbles during the two-minute testing period. None
of the tablets rose to the top within two minutes.
SCANNING ELECTRON MICROSCOPY IMAGING
The films had a relatively smooth and even surface (Figure 6), except for the Water Permeable
3 film, which had approximately 1 µm diameter pores on its surface. The presence of the
tiny pores in the film could explain the behavior of the Water Permeable 3 film in our
different tests. The cross-section (cut surface) of the films was also analyzed with the same
method, however, no pores were identified, and all five nail polish films looked identical.
Figure 4. One-layer nail polish films soaking in water at the end of the 2-hour soaking period.
Figure 5. Effervescent tablet coated with Water Permeable 3 nail polish (A) freshly coated and (B) after
5 minutes of drying.

369 Water Permeability of Nail Polish
CONCERNS WITH CURRENT TESTING METHODS AND THEIR IMPLICATIONS ON CONSUMERS
Water Permeable 1 nail polish claims to use the ASTM D 3985 Standard and the ISO
15105-2:2003 to test the permeability of their product.1 The ASTM D3985 is a standard
test method for oxygen gas transmission rate (OTR) through plastic film and sheeting
using a coulometric sensor.2 The ISO 15105-2:2003 is a test for the determination of
the gas transmission rate of any plastic material in the form of film, sheeting, laminate,
co-extruded material, or flexible plastic-coated material.3 The mentioned methods evaluate
gas transmission rate, however, the major concern with nail polish films is whether water
can penetrate through the film to the nail surface. Another standard parameter often
measured to evaluate the amount of water vapor that could penetrate a film over a given
period is called water vapor transmission rate (WVTR), and one of the standard methods
is called ASTM F1249. While both OTR and WVTR measurements could be helpful
for water permeable nail polish, they have different scopes, different testing conditions
and parameters, and therefore, provide different profiles of the same film. Since OTR and
WVTR are different, one does not equal the other: a film may be permeable to oxygen,
but act as a good barrier against water vapor and vice versa.4,5 When considering nail
polish films though, oxygen and water vapor permeability are not relevant for testing water
permeability. The above discussed tests, i.e., OTR and WVTR, determine how individual
molecules of oxygen, or water in a gas state pass through nail polish film, respectively,
instead of determining how liquid water passes through, which would be more realistic.
There is a big difference between physical states of the same molecule, for example liquid
water and water vapor, in terms of the association of molecules and kinetic energy they
have.6 Even if water vapor passes through a film, liquid water could possibly not do the
same. Another factor to consider is the size of the pores in the film tested. The ideal test
Figure 6. Scanning electron microscopy image of the nail polish films tested in this study. Note: the bottom
right image is a zoomed-in cut version of Water Permeable nail polish 3.