October 26th 06, 07:19 PM
In September, Eric Greenwell started a thread on UV exposure and how
much canopies absorbed. I bought one of the Oregon Scientific units he
recommended (Amazon has a good price, roughly $20, esp if you buy
something else to get over $25 for free shipping.
I have not yet had a chance to try it out under my canopy, but I just
did a test under a white cotton T shirt. The SPF factor seems to be
almost infinite! Pointed at the sun, the meter said 28 minutes was the
safe exposure time for the settings I have on it (SPF=1, moderate
skin). Put under my T shirt, pointed in the same direction, and pulling
the shirt tight to make it as transluscent as possible (as in moving
around) gave a reading of 3959 minutes which is the maximum it will
display. The SPF based on these readings seems to be well over 100, not
the 10 that someone else suggested on that thread. The shirt is
laundered normally, without the special product that poster mentioned
to increase SPF.
I realize this is just one reading, and there may be other factors
(comments please), but the reading is consistent with my experience.
When flying, I use SPF 30 sun screen with titanium or magnesium dioxide
(the only kind my dermatologist says really works) on all exposed
areas, but do not apply it under my T shirt except around the edges,
where it will move and provide partial exposure. I never get even tan
where the shirt covers in spite of no sun screen.
Martin
much canopies absorbed. I bought one of the Oregon Scientific units he
recommended (Amazon has a good price, roughly $20, esp if you buy
something else to get over $25 for free shipping.
I have not yet had a chance to try it out under my canopy, but I just
did a test under a white cotton T shirt. The SPF factor seems to be
almost infinite! Pointed at the sun, the meter said 28 minutes was the
safe exposure time for the settings I have on it (SPF=1, moderate
skin). Put under my T shirt, pointed in the same direction, and pulling
the shirt tight to make it as transluscent as possible (as in moving
around) gave a reading of 3959 minutes which is the maximum it will
display. The SPF based on these readings seems to be well over 100, not
the 10 that someone else suggested on that thread. The shirt is
laundered normally, without the special product that poster mentioned
to increase SPF.
I realize this is just one reading, and there may be other factors
(comments please), but the reading is consistent with my experience.
When flying, I use SPF 30 sun screen with titanium or magnesium dioxide
(the only kind my dermatologist says really works) on all exposed
areas, but do not apply it under my T shirt except around the edges,
where it will move and provide partial exposure. I never get even tan
where the shirt covers in spite of no sun screen.
Martin