SUN PROTECTION
EFFICACY
Georgiev, Mihail
Kamenova, Tsveta
Karastoyanova, Marieta
SUN PROTECTION EFFICACY
Contents:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Abstract – 3
Background – 3
Hypothesis - 4
Experimental Part
Materials – 4
Procedure – 4-6
5.1. Method I – 4-5
5.2. Method II – 5-6
5.3. Method III – 6
Data and Analysis – 7-9
6.1. Method I – 7-8
6.2. Method II – 8-8
6.3. Method III – 9
Discussion - 10
Conclusion – 10
Works Cited – 10
Appendix – 11 - 16
SUN PROTECTION EFFICACY
1. Abstract
This experiment aims to evaluate the efficacy of sunscreen protection. For this purpose, it uses two
suns screen filters whose trade names are Prosun® (Butyl methoxydibezoylmethaneehtylhexylsilicate
caprylic triglyceride) and Prosun-A® ( Ethylhexyl Methoxycinnamate benzophenone-3 homosalate ). We
set out to discover which of the two provides better UV light protection using three different methods.
Method I involves UVA light radiation on yeast cell cultures. Methods II and III require a light
intensity sensor. In method III, pyranine (a substance present in highlighter ink and fluorescent for
UVA light) is also used. This method is sensitive to UV absorption only and provides accurate data. The
three methods experimentally confirm the hypothesis that Prosun-A® is more efficient than Prosun®.
2. Background Information
UV-light (10 - 400 nm) is a form of electromagnetic radiation that is not part of the visible
spectrum. It has a wavelength smaller than that of violet light and longer than that of X-rays (it has
greater energy than violet light and less than X-ray). Little UV light is allowed through the Earth’s
ozone layer. While exposure is beneficial for the production of vitamin D2, about 10 minutes daily are
sufficient for Caucasians non-tropical latitudes to produce the necessary quantity, while people with
darker skin will need more time to acquire the same amount of vitamin D
UVA light (400–315 nm) is absorbed poorly by organisms; UVB light (315–280 nm) is
absorbed by organic matter and thus has the greatest biological significance; UVC light (280–100 nm)
does not reach the Earth’s surface because it is absorbed by almost anything including oxygen (precisely
this is the way the ozone layer is generated).
Most of UV’s effects are on the skin, contributing to sunburn, the appearance of suntan, and in
the case of long-term exposure- wrinkling, thickening of the skin and cancerous processes most
probably because of changes that UV light causes in skin cells’ DNA. People with light skin are even
more predisposed to sunburn, ageing and cancerous processes in the skin due to exposure to UV light.
Prosun-A® - (Butyl methoxydibezoylmethane (Fig. 1a); Ehtylhexylsilicate (Fig.1b),
Caprylic/capric triglycerides (Fig. 1c)) - provides protection from most UVA (400–315 nm), and
UVB(315–280 nm)light, while allowing you to get a little suntan because its maximum absorbance is
reported at 236-356 nm. Each 1% of these 10 % accounts for 0.5 SPF-A, and 0.6 SPF-B protection.
Fig. 1. Ingredients of Prosun-A®
a. Butyl Methoxydibezoylmethane
b. 2-Ehtylhexyl Silicate
c. Caprylic/Capric Triglicerid
SUN PROTECTION EFFICACY
Prosun® - (Ethylhexyl Methoxycinnamate (Fig. 2a); Benzophenone-3 (Fig. 2b), Homosalate
(Fig. 2c)) – provides limited UV-A protection, used against wrinkles caused by the surrounding
environment during sunbathing. It takes up 10% of an examined sunscreen for 30 SPF. Each 1% of
these 10 % accounts for 1 SPF UV protection.
Organic compounds absorb UV light in a different manner from atoms and inorganic
compounds because of their multiple atoms that have electrons of different energies. Graphically,
where there are many electrons with similar electron energy levels, a peak of absorbance is formed.
Thus, Prosun® and Prosun-A® combine several organic compounds with several peaks so as to form a
continuous band broad enough to protect from more significant variety of UV light wavelength than a
single organic compound would.
Fluorescence is the ability of certain substances to absorb high energy
light (e.g. UV light) and re-emit it as lower energy visible light. The principle
of action of fluorescent substances is shown on the Jablonski Diagram (Fig. 3).
The incoming light (high energy) excites the electrons in the fluorescent
substance and raises their energy to an excited state. Those electrons then lose
a part of this energy in smaller steps (3 to 2, 2 to 1, 1 to 0). The conversion
from the lowest excited state to the ground state of the electrons, however,
requires the loss of greater amount of energy than in the non-radiative
transitions, so as to pass through the energy gap between S1 and S0. Therefore,
this energy is emitted in the form of visible light. The emitted light’s energy
will be smaller than the incoming light’s one due to the non-radiative
transitions in the excited state.
Fig. 3. Jablonski Diagram
Source: http://en.wikipedia.org/wiki/Fluorescence#mediaviewer/File:Jablonski_Diagram_of_Fluorescence_Only.png
3. Hypothesis:
Based on a comparative examination of Prosun® and Prosun A® provided by the producer
of the two products, Prosun A® provides better protection from UV light than Prosun®.
SUN PROTECTION EFFICACY
Experimental Part:
4. Materials
Common
Materials:
Additional
Materials for
Method I:
Additional
Materials for
Method II:
• A light sensor
• 1 LabQuest
• 2 CO2 Gas Sensor
packs (sensors and
bottles)
• UV filters:
• Yeast
• A UVA lamp
• Electrical outlet
-
Prosun®
Prosun® A
• 3 identical petri
dishes
• Sugar
• 2 graduated
cylinders
• Warm water
• A ruler
• Microscope slides
and cover slips,
droppers
Aditional Materials
for Method III:
• A light sensor
• A small beaker
(100 mL) with warm
water
• One highlighter
• Instruments to
break the highlighter
• A ruler
• Two pieces of dark
cardboard – one
smaller and one
bigger
• Scissors
5. Procedure
!All the trials should be conducted in a dark room to minimize the effect of other
sources of EMR on the results, especially for methods II and III !
METHOD 1:
Control Group determination
1) Prepare a LabQuest connected to two CO2 sensors + two plastic bottles each filled with 150 ml of
hot tap water, two samples of 15 g of sugar and two samples of 1 g of yeast. (pic.1 – materials)
2) To each of the two bottles add 15 g of sugar measured precisely at a measuring scale.
3) Stir both bottles until the sugar and the water form a solution.
4) Add 1 g of yeast to each.
5) Place one bottle under UV-light and the other in front of a normal source of light.(pic.2)
6) Stir both mixtures for 15 seconds and then simultaneously stop and put one CO2 sensor into each
bottle; the CO2 sensor should have no direct contact with the compound.
7) Press the “Play” button on the LabQuest to begin the measurements + observe data without
interfering with the conditions of the two samples.
8) After the period of 600s that the LabQuest measures, record data in the data table.
9) Repeat step 1 through 8 two more times to ensure consistency of results.
SUN PROTECTION EFFICACY
(pic.1)
(pic.2)
After recording data from the control group, it is time to measure the effects of Prosun® and ProsunA®.
1') Create two samples with Prosun® by using a pipette to put Prosun® on a slide (exactly the amount
needed to cover the slide) and by placing a slit on top of it; the purpose of creating two samples is to
cover one entire wall of the bottle with the two. (pic.3)
2') Repeat steps 1 through 4 for creating the bottle solutions.
4') Attach the two samples with Prosun® next to each other on one of the walls of one of the bottles by
using a pipette to place drops of water on the surface of the wall to use water’s adhesion ability to keep
the samples on the wall of the bottle to protect the yeast inside. (pic.4)
5') Place both bottles under in front of the UV-light lamp.
6') Repeat steps 6 through 9.
7') Repeat steps 1’) through 6’) by replacing Prosun® with the UV filter Prosun-A® in step 1’).
(pic.3)
METHOD 2:
1) Connect the light sensor to the LabQuest.
2) Measure 10 mL of Prosun® and Prosun-A® using the graduated cylinders.
3) Pour the UV filters in two separate petri dishes.
4) Point the UV lamp upwards.
5) Use the ruler to set a distance above it and place the empty petri dish there.
6) Point the sensor directly against the UV light from a set distance – 3 cm. (pic.5)
(pic.4)
7) Record the readings. The sensor will hardly
set on a single value. Record ten of the
numbers displayed and then find the average.
8) Remove the sensor.
9) Replace the empty petri dish with the one
with Prosun®.
10) Repeat steps 7) and 8) for Prosun®.
11) Repeat steps 9) and 10) for Prosun-A®.
(pic.5)
METHOD 3:
1) Break the highlighter with the instruments and extract the part soaked in ink.
2) Put the part in a beaker with warm water and leave it for 3 days.
3) Cut a small hole in a piece of cardboard, which is big enough to cover the opening of the UV-light
from which light is escaping, so that only a ray of light goes out.
4) Place one of the bottles with the UV filters on the path of the ray. Place the beaker (remove the
highlighter part) behind it (the ray firstly passes through the UV filter and then through the beaker).
Make sure the bottle and the beaker touch. (pic.6)
7) Measure the distance between the hole in the cardboard and the far end of the bottle with the UV
filter (in our case, 7cm) and the distance between the hole in the cardboard and the far end of the
beaker with the highlighter ink water (in our case, 12 cm).
8) Remove the beaker and the bottle.
9) Use the light sensor to measure the light intensity at the slit from cardboard (distance 0 cm), at the
place of the end of the UV filter bottle (distance 7 cm) and at the place of the end of the beaker
(distance 12 cm) to see how the light intensity changes with the distance.
10) Record the readings. The sensor will hardly set on a single value. Record ten of the numbers
displayed and then find the average.
11) Place the beaker (but not the bottle with the filter) as if the bottle was there (the edge at 12 cm.)
12) Point the sensor directly to the light and touch the end of the sensor to the wall of the beaker
13) Measure the light intensity of the ray coming through the fluid.
(pic.6)
SUN PROTECTION EFFICACY
6. Data and Analysis
Method I:
Independent variable: presence/type of an UV filter
Dependent variable: amount of CO2 in the bottle (CO2 reading of the sensor)
Constants: UV light source; UV light intensity; distance from the UV lamp; type and amount of
yeast; type and initial temperature of the water; type and amount of sugar; time period of the
measurement; time of stirring the solution before starting to measure the CO2 amount in the bottle;
bottles; additional light (lamps, daylight coming from the window); amount of filter
General idea: The more CO2 the sensor reads, the more the yeast has breathed for the time period.
The more the yeast breathed, the more it had reproduced/had not died. Therefore, the more CO2
present in the bottle after the 10-minute period, the more UV light has been absorbed by the UV filter.
Sources of Error:
 Dispersion of yeast in the container might not have always been the same.
 When exposed to UV light, yeast’s membranes can be destroyed and nitrogenous compounds
released in the surroundings; these nitrogenous compounds stimulate division in the
surrounding yeast cells. It is not possible to control the release of those nitrogenous compound,
and their stimulating effect on yeast. This is why in several trials the balance of killed vs.
stimulated is different and we can’t accurately compare the two or more experimental groups
with the control groups.
The Effect of Temperature: The fact that the UV lamp doesn’t just light the sample in front of it,
but also heats it cannot be ignored. Therefore, a control sample of yeast was heated without being
exposed to the UV lamp. Another sample was heated only by the UV lamp. Although both the final
temperature and initial amount of CO2 was slightly bigger in the heat only sample, the UVA sample
showed greater final CO2 amount; that indicates greater yeast population, which means it is not only the
heat generated by the UV lamp that stimulates yeast to reproduce, but also the UVA light it is exposed
to.
The Effect of UV Filters
The samples were created as described in Procedure. Here again, greater CO2 amount signifies
greater yeast population. The results from that experiment are shown in Graph 1.
Graph 1. Amount of CO2 vs. Filter
80000
60000
40000
20000
0
No Protection
Prosun®
Prosun-A®
The protected samples generally have greater amounts of CO2 than the unprotected ones.
According to the results above, the samples protected with Prosun-A® have the greatest average
SUN PROTECTION EFFICACY
amount of CO2. Therefore, we can conclude that the yeast populations in them were best protected;
that is, Prosun-A® absorbs the most UV light, and is the best UV filter from the ones we tested.
We were not able to get consistent data from our measurements with method I. When we applied
filters, sometimes we got contradictory results. Therefore, we wanted to further test our hypothesis and
findings using other methods as well.
Method II:
Independent variable: presence/type of an UV filter
Dependent variable: light intensity measured by the Light Sensor
Constants: UV light source; distance between the UV lamp and the filter; distance between the
filter and the sensor; light sensor; absence of additional light; type of petri dishes; amount of filter
General idea: the sensor measures light coming from the source. Since the light is UV, and the
filters are supposed to absorb it (or at least part of it), the less light passing through the filter and
reaching the sensor, the more UV light (the experiment is performed in a dark room, there is no
additional light) is absorbed, and consequently, the better the filter. The results are shown in Graph 3.
Source of Error:
The intensities that we measure (in lux) account not only for ultraviolet light, but also for the
visible light emitted by the ultraviolet lamp, used in the experiment.
The Effect of Distance:
As noted in the Inverse-Square Law, the light
intensity measured at a specific point depends on the
inverse square of distance between the light source and
the point (Graph 3). Therefore, all the measurements in
Method II and Method III were taken at the same
distance between the UV lamp and the light sensor.
Graph 2. Inverse-Square Law
Source: http://www.physicalgeography.net/fundamentals/6f.html
Graph 3. Detected EMR Intensity vs. UV Protection
1400
1200
1000
800
600
400
200
0
Average Detected EMR
Intensity in (lux)
Glass Only
(Control Group)
Prosun
Prosun A
SUN PROTECTION EFFICACY
The least amount of light reaching the sensor is registered when Prosun-A® filter is applied.
Prosun-A® absorbs more UV light than Prosun®. Therefore, it is the better UV light filter.
Method III:
Independent variable: presence/type of an UV filter
Dependent variable: light intensity measured by the Light Sensor
Constants: UV light source; distance between the UV lamp and the filter; distance between the
filter and the beaker with water and highlighter ink (0 cm); distance between the beaker and the sensor
(0 cm); light sensor; absence of additional light; amount of filter; identical bottles for the different
filters; same beaker and highlighter ink water.
General idea: Highlighter ink is fluorescent for UV light. Therefore, the UV light passing
through it is converted into normal visible light which the sensor catches. When the UV light ray passes
through a filter before entering the beaker with highlighter ink water, some of this UV light is absorbed
and doesn’t reach the beaker, and the sensor behind it. Therefore, the less intensity the light sensor
reads, the less light has reached the beaker, the more light has been absorbed by the filter, and the
better the filter is.
Source of Error:
The intensities that we measure (in lux) without the highlighter ink account not only for
ultraviolet light, but also for the visible light emitted by the ultraviolet lamp, used in the experiment, but
were used to compare to the results of each filter through the pyranine solution.
Our findings are summarized in Graph 4.
Graph 4. The Effect of Filter on UVA Light Intensity (in lux) (Measured at 12 cm
From the Source)
150
UVA Light Only
140
UVA Light Passing Through
WDHI
130
120
UVA Light Passing Through a
UV Filter
110
100
Prosun®
Prosun-A®
UVA Light Passing Through
WDHI* AND a UV Filter
*WDHI – Water with Dissolved Highlighter Ink(pyranine solution)
The reading of the sensor reflects the part of the original light that has not been absorbed by
the filter or the fluorescent fluid.
Prosun-A® absorbs more light than Prosun®. When Prosun-A® is applied, less UV light
reaches the fluorescent highlighter ink and less light is passed on to the sensor. Therefore, Prosun-A®
is the better UV filter.
SUN PROTECTION EFFICACY
7. Discussion
Prosun-A® probably absorbs more UV light than Prosun® because of its chemical
configuration. The chemical configuration determines the specific electrons and excitement levels. The
wider the band of excitement levels a compound produces the wider range of wavelengths it could
absorb. Prosun-A® has silicon, while Prosun® doesn’t. This silicon supplies some additional electrons
with different from the other atoms’ excitement levels that would create a wider band. The wider the
range of elements in a compound, the greater chance there is for a wide range of wavelengths absorbed
by the compound. What is more, with the silicate ion in the center, it is more likely that it has a
profound effect on the electron density in the other parts of the molecule, as hypothesized by
Molecular Orbital Theory.
8. Conclusion
Our hypothesis was confirmed: Prosun® A absorbs more UV light than Prosun® because of
its chemical composition that allows it absorb a wider range of UVA frequencies.
9. Works Cited
Compound Interest. "The Chemistry of Highlighter Colours." Compound Interest. 2015 Compound
Interest | EXPLORATIONS OF EVERYDAY CHEMICAL COMPOUNDS, 22 Jan. 2015.
Web. 2 Mar. 2015. <http://www.compoundchem.com/2015/01/22/highlighters/>.
"How to Get Vitamin D from Sunlight." NHS.uk. The Editors of NHS.uk.. Web. 23 Nov. 2014.
How Fluorescence Works - The Science. Dir. NurdRage. YouTube. YouTube, 23 Dec. 2012. Web. 2 Mar.
2015. <https://www.youtube.com/watch?v=CcssdJf0pKQ>.
"How Much Sun Is Enough?" Cancer Council Australia. The Editors of the Cancer Council of Ausrtalia
website., 25 Sept.2014. Web. 23 Nov. 2014.
"How Sunscreens Block: The Absorption of UV Light." The Editors of the Nanosense Project, n.d.
Web. 23 Nov. 2014.
<http://nanosense.sri.com/activities/clearsunscreen/absor®ption/CS_Lesson3Teacher.pdf>.
Kotz, John C., and Paul Treichel. "Molecular Orbital Theory." Chemistry & Chemical Reactivity. South
Melbourne, Vic., Australia: Thomson-Brooks/Cole, 2003. N. pag. Print.
The Editors of Encyclopædia Britannica. "Ultraviolet Radiation." Encyclopedia Britannica Online.
Encyclopedia Britannica, 4 Oct. 2014. Web. 23 Nov. 2014.
SUN PROTECTION EFFICACY
10. Appendix
Data and Analysis
Method I:
Independent variable: presence/type of an UV filter
Dependent variable: amount of CO2 in the bottle (CO2 reading of the sensor)
Constants: UV light source; UV light intensity; distance from the UV lamp; type and amount of
yeast; type and initial temperature of the water; type and amount of sugar; time period of the
measurement; time of stirring the solution before starting to measure the CO2 amount in the bottle;
bottles; additional light (lamps, daylight coming from the window); amount of filter
General idea: The more CO2 the sensor reads, the more the yeast has breathed for the time period.
The more the yeast breathed, the more it had reproduced/had not died. Therefore, the more CO2
present in the bottle after the 10-minute period, the more UV light has been absorbed by the UV filter.
1) UV Light Effect on Yeast
The Effect of UV Light on Yeast Population Growth
40000
30000
20000
Exposed to UVA Light
10000
Unexposed to UVA Light
0
Exposed to UVA Light
Unexposed to UVA Light
2) The Effect of temperature
We couldn’t ignore the fact that the UV lamp doesn’t just light the sample in front of it, but also
heats it. Therefore, we heated one of the samples artificially (not the one in front of the UV lamp) and
left the other to be heated only be the lamp. The results are in the chart below.
Although both the final temperature and initial amount of CO2 was slightly bigger in the heat
only sample, the UVA sample showed greater final CO2 amount; that indicates greater yeast population,
which means it is not only the heat generated by the UV lamp that stimulates yeast to reproduce, but
also the UVA light it is exposed to.
Average Increase in the Amount of CO2
50000
40000
30000
UVA Light
20000
Heat Only
10000
0
Trial 1
Trial 2
SUN PROTECTION EFFICACY
3) The Effect of UV Filters
The samples were created as described in Procedure. Here again, greater CO2 amount signifies
greater yeast population. The results from that experiment are shown in the graph.
UV Filter vs. Amount of CO2
80000
60000
40000
With Filter
20000
0
Control Group
Prosun®
Prosun-A®
Difference Protected - Unprotected (ppm)
6000
4000
Difference (ppm)
2000
0
Control
Prosun®
Prosun-A®
The control group for this experiment was created by minimizing the differences between the
two bottle samples, where one was exposed and the other wasn’t exposed to UV-light. Because the
UV-light lamp not only provides thermal energy, but also produces visible light, the unexposed bottle
sample had to be put under the same conditions, for which reason we used a normal lamp as the light
and heat source to affect the growth of the yeast population.
The protected samples generally have greater amounts of CO2 than the unprotected ones. This
contradicts with our results with the pre-lab experiment to determine whether UV light stimulates or
kills yeast. According to the results of the pre-lab experiment, yeast is stimulated by UV light and the
yeast population in the UV samples grows faster than the population that had not been exposed to UV
light.
However, when we use UV filters, the sample should be protected from UV light. Consequently,
the difference in the yeast population growth in samples whose CO2 levels are being measured
simultaneously, but only one of whom is protected, should be the real difference between yeast
exposed and yeast unexposed to UV light. From that, it can be concluded that UV light kills or at least
slows the growth and reproduction of yeast populations.
According to the results above, the samples protected with Prosun-A® have the greatest average
amount of CO2. Therefore, we can conclude that the yeast populations in them were best protected;
that is, Prosun-A® absorbs the most UV light, and is the best UV filter from the ones we tested.
SUN PROTECTION EFFICACY
*We were not able to get consistent data from our measurements. When we applied filters, sometimes
we got contradictory results. Therefore, we wanted to test our hypothesis and findings using two other
methods as well.*
Method II:
Independent variable: presence/type of an UV filter
Dependent variable: light intensity measured by the Light Sensor
Constants: UV light source; distance between the UV lamp and the filter; distance between the
filter and the sensor; light sensor; absence of additional light; type of petri dishes; amount of filter
General idea: the sensor measures the light coming from the source. Since the light is UV, and
the filters are supposed to absorb it (or at least a part of it), the less light passing through the filter and
reaching the sensor, the more UV light (the experiment is performed in a dark room, there is no
additional light) is absorbed, and consequently, the better the filter. The results are shown in the table
below.
Detected EMR Intensity vs. UV Protection
1400
1200
1000
800
600
400
200
0
Average Detected EMR
Intensity in (lux)
Glass Only
(Control Group)
Prosun
Prosun A
EMR Absorption of Prosun and Prosun A (in Per
Cent)
100
50
Per Cent EMR…
0
Prosun®
Prosun-A®
The least amount of light reaching the sensor is registered when Prosun-A® filter is applied.
Prosun-A® absorbs more UV light than Prosun®. Therefore, it is the better UV light filter.
SUN PROTECTION EFFICACY
Method III:
Independent variable: presence/type of an UV filter
Dependent variable: light intensity measured by the Light Sensor
Constants: UV light source; distance between the UV lamp and the filter; distance between the
filter and the beaker with water and highlighter ink (0 cm); distance between the beaker and the sensor
(0 cm); light sensor; absence of additional light; amount of filter; identical bottles for the different
filters; same beaker and highlighter ink water
General idea: Highlighter ink is fluorescent for UV light. Therefore, the UV light passing
through it is turned into normal visible light which the sensor catches. When the UV light ray passes
through a filter before entering the beaker with highlighter ink water, some of this UV light is absorbed
and doesn’t reach the beaker, and late the sensor. Therefore, the less intensity the light sensor reads, the
less light has reached the beaker, the more light has been absorbed by the filter, the better the filter is.
Our findings are listed below:
1) Light Intensity in Relation with the Distance with the Source
Average Intensity (in lux)
2500
2000
1500
1000
Average Intensity (in lux)
500
0
Average Intensity (in lux)
0 cm
2128.2
7 cm
227.8
12 cm
141.9
The further away from the source the sensor gets, the smaller light intensity it reads.
*for all other measurements, the distance between the light sensor and the slit from which the ray
comes is 12 cm.
2) UV Light Passing Through Highlighter Ink Water Only
*WDHLI – Water with Dissolved Highlighter Ink
EMR Intensity With and Without Water with Dissolved
Highlighter Ink (at 12 cm from the Source)
160
150
140
Measured EMR Intensity (in
lux)
130
120
Passing Through Water
with Highlighter Ink
No Water with
Highlighter Ink
SUN PROTECTION EFFICACY
3) UV Light Passing Through a Filter
The Effect of Filter on UVA Light Intensity (in lux)
(Measured at 12 cm From the Source)
UVA Light Only
150
145
140
135
130
125
120
115
110
105
100
UVA Light Passing
Through WDHLI*
UVA Light Passing
Through a UV Filter
Prosun®
Prosun-A®
UVA Light Passing
Through WDHLI* AND a
UV Filter
The reading of the sensor reflects is the part of the original light that has not been absorbed by
the filter or the fluorescent fluid, or both.
Prosun-A® absorbs more light than Prosun®. When Prosun® is applied, less UV light reaches
the fluorescent highlighter ink and less light is passed on to the sensor. Therefore, Prosun-A® is the
better UV filter.