I'm looking for any independent experiments, articles, or data that actually looks at the ability of waxes or sealants to protect paint from UV as so many products claim. Anybody come across anything with some objectivity? I really would like to put these claims to the test because UV protection is so readily touted. Consumer reports??
I am considering the following experiment:
1) acquiring an accurate UV index photometer
2) building a test box with a UV probe and strong CFL UV source (black light)
3) treating sections of uncoated framing glass and/or plexiglass with different sealants/waxes/lsps
4) measuring the ability of the products to absorb (or reflect) UV light (when compared to control blanks)
I would taking measurements a) after the products has cured, b) after 8 hours of exposure to a realistic UV intensity, c) after simulated rain or washing, d) after 1 week exposed outside in Indiana, and e) after 1 month of exposure.
I may even build an apparatus to expose four or more products to UV light simultaneously so the experiment would not take forever to execute.
I would need extremely small quantities of several products (free samples!).
Questions:
1) Would it be safe to assume that most sealants or waxes would function when applied to glass or plexi?
2) Are there other alternative substrates you can think of that would allow light penetration and are affordable? I was thinking I could have a body shop clear-coat some plexi, or I could do it myself.??
3) Is there a more appropriate way to measure UV absorbance/reflectance?
It sounds like this could generate some fairly useful data if I can get a meter that actually measures only UV.
From wikipedia:
The UV index is a number linearly related to the intensity of UV radiation reaching the surface of the earth at a given point. It cannot be simply related to the irradiance (measured in W/m2) because the UV of concern occupies a spectrum of wavelength from 295 to 325 nm and shorter wavelengths have already been absorbed a great deal when they arrive at the Earth's surface. Skin damage, however, is related to wavelength, the shorter wavelengths being much more significant. The UV power spectrum (strictly expressed in watts per square metre per nanometre of wavelength) is therefore weighted according to a weighting curve known as the McKinlay-Diffey Erythema action spectrum, and the result integrated over the whole spectrum. This typically gives a figure of around 250 in mid-day sun and so is arbitrarily divided by 25 to generate a convenient index value, which becomes essentially a scale of 0 to 10 (though ozone depletion is now resulting in values above ten as commented above).[3] Because the scale is linear and not logarithmic, as is often the case when measuring things such as sound level or brightness, it is reasonable to assume that one hour of exposure at index ten is approximately equivalent to two hours at index 5, although other factors like the body's ability to repair damage over a given time period could detract from the validity of this assumption.
To illustrate the weighting principle, the incident power density in mid-day sun is typically 0.6 mW/(nm m2) at 295 nm, 74 mW/(nm m2) at 305 nm and 478 mW/(nm m2) at 325 nm. (Note the huge absorption that has already taken place in the atmosphere at short wavelengths.) The weighting factors applied to these figures are 1.0, 0.22, and 0.03 respectively. (Also note the huge increase in damage caused by the shorter wavelength, i.e., 305 nm is 22% as damaging as 295 nm, and 325 nm is 3% as damaging as 295 nm.) Integration of these values using all the intermediate weighting values over the spectral range of 305 nm to 325 nm produces a figure of 264, which is then divided by 25 to give an index of 10.6.[3]
I am considering the following experiment:
1) acquiring an accurate UV index photometer
2) building a test box with a UV probe and strong CFL UV source (black light)
3) treating sections of uncoated framing glass and/or plexiglass with different sealants/waxes/lsps
4) measuring the ability of the products to absorb (or reflect) UV light (when compared to control blanks)
I would taking measurements a) after the products has cured, b) after 8 hours of exposure to a realistic UV intensity, c) after simulated rain or washing, d) after 1 week exposed outside in Indiana, and e) after 1 month of exposure.
I may even build an apparatus to expose four or more products to UV light simultaneously so the experiment would not take forever to execute.
I would need extremely small quantities of several products (free samples!).
Questions:
1) Would it be safe to assume that most sealants or waxes would function when applied to glass or plexi?
2) Are there other alternative substrates you can think of that would allow light penetration and are affordable? I was thinking I could have a body shop clear-coat some plexi, or I could do it myself.??
3) Is there a more appropriate way to measure UV absorbance/reflectance?
It sounds like this could generate some fairly useful data if I can get a meter that actually measures only UV.
From wikipedia:
The UV index is a number linearly related to the intensity of UV radiation reaching the surface of the earth at a given point. It cannot be simply related to the irradiance (measured in W/m2) because the UV of concern occupies a spectrum of wavelength from 295 to 325 nm and shorter wavelengths have already been absorbed a great deal when they arrive at the Earth's surface. Skin damage, however, is related to wavelength, the shorter wavelengths being much more significant. The UV power spectrum (strictly expressed in watts per square metre per nanometre of wavelength) is therefore weighted according to a weighting curve known as the McKinlay-Diffey Erythema action spectrum, and the result integrated over the whole spectrum. This typically gives a figure of around 250 in mid-day sun and so is arbitrarily divided by 25 to generate a convenient index value, which becomes essentially a scale of 0 to 10 (though ozone depletion is now resulting in values above ten as commented above).[3] Because the scale is linear and not logarithmic, as is often the case when measuring things such as sound level or brightness, it is reasonable to assume that one hour of exposure at index ten is approximately equivalent to two hours at index 5, although other factors like the body's ability to repair damage over a given time period could detract from the validity of this assumption.
To illustrate the weighting principle, the incident power density in mid-day sun is typically 0.6 mW/(nm m2) at 295 nm, 74 mW/(nm m2) at 305 nm and 478 mW/(nm m2) at 325 nm. (Note the huge absorption that has already taken place in the atmosphere at short wavelengths.) The weighting factors applied to these figures are 1.0, 0.22, and 0.03 respectively. (Also note the huge increase in damage caused by the shorter wavelength, i.e., 305 nm is 22% as damaging as 295 nm, and 325 nm is 3% as damaging as 295 nm.) Integration of these values using all the intermediate weighting values over the spectral range of 305 nm to 325 nm produces a figure of 264, which is then divided by 25 to give an index of 10.6.[3]
