“What is the difference between a 10-minute lamp and a 20-minute lamp? What happens if you install a 10-minute lamp in a 20-minute bed?”
Perhaps a better question is, What is the difference between a 10-minute bed and a 20-minute bed?
A sunlamp’s performance is directly related to the tanning equipment in which it is installed. The same lamp may have different exposure schedules in various models of equipment. Factors such as the transmissive quality of the acrylic shield, the distance of the lamps from the tanner, the ballasts used, bed geometry, electrical current/voltage, number of lamps and the distance between the lamps, and the effectiveness of the reflector system all influence what the exposure schedule and maximum timer interval will be.
Remember to use a hand-held UV meter to monitor your lamp’s depreciation and replace them when the output drops 30% from initial readings.
By using a “standard” or “typical” sunbed for evaluation, a lamp manufacturer can estimate a lamp’s TE or exposure time. When consistently applied, this method gives you a pretty good idea of what to expect in your application. Given the same sunbed, a “10-minute” lamp will deliver twice the erythemal effectiveness of a “20-minute” lamp. This is usually accomplished by increasing the UVB (280-320nm) and UVA2 (320-340nm) output at the expense of UVA1 (340-400nm). Higher wavelength UVB and UVA2 are most closely associated with photoaging (wrinkles), vitamin D synthesis, melanin formation and some pigment darkening. UVA1 penetrates the skin further and contributes to robust pigment darkening and longer-lasting tans.
To answer the second part of the question, all tanning units, regardless of timer interval or lamp type may produce a maximum of four (4) MED (minimal erythemal dose). An MED refers to the least amount of UV radiation a person can receive which induces a distinct erythema or “pinkening” of the skin within 7-24 hours following exposure. Always replace lamps with the same model as what is listed on the tanning unit label, or an FDA compatible alternative. A compatible replacement lamp should not change the exposure schedule by more than 10%. Therefore, a compatible replacement lamp for a 20-minute bed should have a TE in the 18-22 minute range (10% of 20 minutes is +/- 2 minutes). Therefore, a “10-minute” lamp in a 20-minute bed would change the exposure schedule by more than +/- 2 minutes and would end up overexposing your salon guests unless you reduced their exposure time. Team Wolff recommends against using a non-compatible replacement lamp in your tanning systems. ■
