One of the great features of SoftForm Lighting light forms is the ability to print images on the light diffusing fabric. Doing so enables the application of biophilic design elements like analogous references and repeating biomorphic forms. But printing on SoftForm Lighting's base white fabric does come with an efficacy cost.
Basically the more dense the printing, in other words the darker the colors, the less light passes through the fabric. But keep in mind, images render very well with a small amount of lumens. So the full lumen capability of our light forms is not necessary to create stunning effects with graphics. However, if the delivered lumen value is an important detail to know, the effective light transmission can be factored using our published photometry files .
A comparative evaluation conducted by Independent Testing Laboratories (ITL) measured the light output of a series of non-printed (white) and printed SoftForm Lighting fabric panels. For each panel type, five readings were taken. One in the center and four additional at each corner. The light transmission was compared to the same light form without a fabric panel diffuser. The measured results are as follows:
This comparative evaluation tells that, the denser the print (think dark colors), the less light is able to penetrate the fabric. In order to factor the delivered absolute lumens for a printed panel, we need to change the comparative base to the non-printed white fabric diffuser. The math involved in pretty straight forward (% printed fabric test x 100%) / % non-printed fabric test. So the new transmission percentages, relative to the non-printed fabric, would be:
Light Printed = 80% (0.43 x 100 / 0.54)
Dark Printing = 30% (0.16 x 100 / 0.54)
As an example, if we if take our SFR44 9/16 HO 40 120V light form, the measured absolute lumens equals 14,765 with a white, non-printed fabric panel diffuser. To factor you would multiply the published value by the either 80% for a light print, 30% for a dark print, or a value somewhere in between. Again using our example the factored absolute lumen values would be as follows:
No Print = 14,785 lumens
Light Print = 11,828 lumens
Dark Print = 4,436 lumens
The above values would be considered maximum since the drive current selected in our example is High Output (HO). Lower values can be achieved by the selecting a different driver current (Standard Output, or Low Output) and by dimming as well.
If you would like to see this comparison live, reach out to your SoftForm Lighting agency representative for a demonstration. The printed panels used for the relative transmissive evaluation (SFG001, SFG008) are included in their SoftForm Lighting demonstration sample kit. And you can view and/or download the full report.