QuantaDose UVC Dosage Cards – Photo Degradation Effects Photochromic Materials

Important things you must understand about QuantaDose® test cards before you buy one!


If you are not getting a color change displaying the word ULTRAVIOLET in the lower section of the Quantadose test card while the UV-C indicator is green, the UVC light is likely not reaching the desired level of germicidal intensity required under the current CDC guidelines for intensity levels to achieve disinfection in under ten minutes.

How many times can the intensity test be reused before photo-degradation effects dose accuracy? As for the top test area, there is no limit, however, for the bottom test area, there is!

This takes some explaining why we can’t just simply give you a number of times the card’s lower test area should be used because person A, could be using 9-watt bulbs and person B could be using 60-watt bulbs. Unlike the conventional use of reversible UV photochromics where energy from the sun hitting the earth’s surface is easy to average making it fairly easy to give an approximate number of times a test area can be reused in 15-second intervals. This isn’t the case for reusable UVGI applications.

The key determinant is the cumulative amount of exposure to UV radiation, and not the number of times the photochromic material is cycled between exposure, also important is the environment in which the material finds itself since this can influence its photochemistry too.

The stability of photochromic materials is dependent upon numerous factors, which is the biggest reason we need your support to continue revolutionizing photochromic materials to meet the needs of a cost-effective and accurate UVGI testing method for end consumers and UVC install technicians. Since the pandemic began general UVC disinfection techniques have moved from hospitals to living rooms requiring a more durable and cost-effective means to visualize UVGI exposure.

Ok, back to the question, as it needs to be. How do I check if photo-degradation has affected the accuracy of QuantaDose® UVGI intensity results?

A brand new test card will begin showing the color change in the lower test area at 300 Microwatt [µW/cm²]. When color change exceeds 500 µW/cm² the test card should no longer be used to verify UVGI intensity. The easiest way to do this is with a known wattage and distance, because of their low cost, a 253.7nm 3 watts Chinese made sanitizer wand (We offer one for free with 5 Card UVC Installer Kit) can be used at a distance of 1 inch to confirm the color change is within specs suggested for under 10 min disinfection times.

For more details on the calibration of the dose intensity area see our 5 Card Professional UVC Installer Kit that includes a free 3 Watt UVC calibration light and reusable black Mylar bag for the safest possible storage.

The top QuantaDose UVGI wavelength indicator uses narrow band UVC fluorescent materials that are highly resistant to photo-degradation, so the upper UVGI wavelength indicator has no limit of usage. Now that you know the important stuff, let us get into what this card is all about, how it compares to irreversible UVC dosage cards, and what QuantaDose® photochromic material innovations can do for you!