Blog articles about new related events and issues.

Long Wave Filters are Now More Expensive, #400 LW Filter Glass is no Longer Made

Kokomo Opalescent Glass (KOG) in Kokomo, IN is America’s oldest art glass company. Because they have been losing money trying to make acceptable #400 LW filter glass, the management has decided to discontinue the production of that #400 glass.

The History of #400 LW Filter Glass

KOG has been making #400 LW filter glass for maybe 50 years (they do not even know how long) as one of their 22,000 variations of sheet glass. Their rolled sheet glass can be as large as 35” x 45” (see their website for how they roll their sheets). Recently for whatever reason they have not been able to produce the #400 filter glass even though they have put considerable amount of time and money into that effort. So they decided that they will no longer attempt to make it. In the past the #400 LW filter glass was reasonably inexpensive because it was made as a raw rolled art glass about 2.8 to 3.2 mm thick. It was always much less expensive than LW or SW filters from other sources. To my knowledge KOG was the only company in the US that made LW filters in larger sizes (up to about 45” long).

Art Glass vs Scientific Glass LW Filters

The other companies in the US, Japan, and Germany that make LW filters specialize in technical optic filters for the scientific community. Therefore their filters are much more expensive than filters made by an art glass company. Also, those other companies have standardized their glass production so the largest standard flat filter they make is 6 ½” square (165 mm square) at 5 mm thick. Also most of the scientific optic filter glass is polished after molding. This makes their glass even more expensive. Molded as-poured flat filters are available for some filters but they are thicker (7 mm to 11 mm) and therefore have less UV transmission.

Advantage vs. Disadvantage of Scientific LW Filters

The advantage of using these scientific LW filters is they transmit almost none of the 404.7 nm and 435.8 nm mercury emission lines that are generated in almost all UV light assemblies. Therefore, when looking at your LW fluorescent minerals you do not see any addition visible light that can reflect off of dim or non-fluorescent specimens (you have to see that to appreciate that advantage). Also, much more accurate spectral transmission curves are available with the scientific LW filters. The disadvantage is that their LW filters are normally made much thicker than 3 mm and therefore with less UV transmission. Because the scientific LW filters are thicker you do not get as much LW UV light on your fluorescent specimens as you would with the #400 LW filters. Also, the scientific LW filters are in some cases more than100 times more expensive than the #400 filters were.

Availability of the #400 LW Filters

UV SYSTEMS, Inc. has a limited stock of the old #400 LW filters in stock in four sizes. These are the FL-01 at 3” x 17”, the FL-02 at 6” x 18”, the FL-20 at 2” x 5.5” and the FL-60 at 2.65” x 9.25”. We have enough of the #400 filters for the foreseeable future for the production of our LW350 or LW370 SuperBright 3, TripleBright II, and Dual TripleBright II UV lights. Because we had to purchase some #400 stock from a glass vendor instead of directly from KOG the price for the FL-60 size filter is considerably more per square inch than the other #400 filter stock we have.

Scientific LW Filters

If UV SYSTEMS, Inc. is required to obtain the more expensive scientific LW filters our prices will have to be adjusted accordingly.

Some History about LW Filters

LW Roundels for high pressure mercury arc lights have been made for over 75 years and are still being made. Those roundels are usually 5 5/8” or 6.3” round for those mercury arc lights. Since those round filters are convex on the front and concave on the back they are usually not suited for most hand-held or display UV lights. Those LW filter roundels use a special glass formulation to make then less susceptible to the high IR and heat from those 100W to 175 W lamps; therefore they are not inexpensive. They are also much thicker then the #400 with a different formation to not transmit the powerful visible light generated by those 100W to 175W lamps.

Flat sheet LW filters were made by a few companies back in the early 1950’s since LW fluorescence was popular back then. Road side billboards were made back then that had LW UV fixtures that would fluoresce the whole billboard at night (very dramatic). Those required large flat filters for the many 4 foot long lamps used in those fixtures. Also in large cities like Chicago they had taxicabs with LW signs on the back of their cabs with portable powered LW UV lights that lit up their fluorescent signs at night. My second LW UV light that I built in 1952 still has one of those flat polished filters in it. Back then I also used to have a flat LW filter with molded ridges in it to defuse the UV light. At the time I was told that the filter was made in France. I am sure that those specific LW filter companies are no longer making those filters or are out of business just as those companies that made those UV light assemblies for billboards are no longer in business.


Used SW TripleBright II for Sale at a Huge Discount [SOLD]


Update: This item has been sold. Thank you!

[9-22-2016] UV SYSTEMS, Inc. has one used SW TripleBright II model FSLS for sale. The normal price for the FSLS is $1,149.50 plus Shipping & Handling (S&H) of $22.65 within the USA. This used SW TripleBright II is only $772.00 plus S&H of $22.65 within the USA. First come first serve, only one is available.

This SW TripleBright II is estimated to have only been used for approximately 200 to 400 total hours. The two SW filters are pristine with no white film or dots on them. These SW filters have a transmission that averages about 48% transmission at 253.7 nm. And a brand new SW Hoya U-325C filter has a transmission of about 60% at 253.7 nm, and should last about 7000 hours. So there is lots of life left in these SW filters. The SW lamp (bulb) has almost no depreciation since the patented circuit allows millions and millions of “on-off” cycles without any lamp failure.

The original owner purchased the SW TripleBright II in 2007 and passed away in 2016. A customer purchased the UV light from the estate and then sold it back to UV SYSTEMS, Inc. To purchase, order a SW TripleBright II model FSLS from our store, but in the comment section write “I want the used SW TripleBright II for $772.00 ” and then we will only charge you $772.00 plus the $22.65 S&H. If you live out of the USA, contact UV SYSTEMS, Inc. to find out what the S&H will be.

Phone: (425) 228-9988
Cell phone: (206) 818-1084
Toll free: 1-877-689-5142


T-20 Timer Available for Spectacular Changing Light Show

The T-20 electronic timer is now available. The T-20 custom made model has four outputs and can, for example, turn “on” and “off” a LW UV light, a SW UV light, and a MW UV light, and can also dim down and ramp up your incandescent lights. A typical timing cycle might have the incandescent lights “on” as potential viewers stroll by, at which point a proximity detector starts the cycle, dims the incandescents to “off” and immediately turns the LW UV “on.” Next LW goes “off” and SW comes “on.” Then LW comes back “on” so you have both LW and SW together. Finally, both LW and SW go “off,” and you can see the phosphorescence of the minerals.

As the show draws to a close, the incandescent lights slowly ramp up, avoiding the discomfort of a sudden increase of light. Of course, a push-button switch can also be used to start the cycle, activated by viewers in the museum. The standard four outputs can be expanded to eight or more, and, along with scores of different timing cycles, provide unlimited opportunity to exercise your creativity in designing your display. Some curators may want to include narration and background music. The heart of the custom made T-20 is a Programmable Logic Controller (PLC) which stores the timing cycle in non-volatile memory. Contact UV SYSTEMS, Inc. for more information.



UV SYSTEMS, Inc. 24th Year in Business

UV SYSTEMS started as a sole proprietorship in Feb. of 1992 and became incorporated in Dec. of 1999. We have over 2800 customers listed, with customers in every state in the USA and in scores of countries around the world.

Melissa Russell, Executive Assistant for UV SYSTEMS, Inc.

Melissa is married and has 2 boys ages 15 and 10. She graduated from Seattle University in 1995. She worked in sales for 10 years before deciding to become a stay at home mom. Melissa has been with UV SYSTEMS, Inc. since July 2012. She works part time processing orders, managing inventory and bookkeeping. When she is not at work she manages her family. Both boys are involved in wrestling and baseball. In their spare time they enjoy hiking, camping and spending time with family.


Largest Ever Display of Fluorescent Minerals on the West Coast

Being aware that not every FMS member would be able to attend the 2015 FMS annual meeting in Kelso, WA in Oct., arrangements were made to contract a professional videographer to record the 28 cases of fluorescent minerals that were on display at the meeting. The video was made to give those not in attendance the opportunity to view the world class cases displayed by the attending FMS members.

The informative video is narrated by Glenn Waychunas, PhD. In that there was a cost associated with the production of the video, there is a recovery fee being requested. This online video is available for $13.95 to offset the cost of production. Any fees generated above the cost of the production will be donated to the FMS. This video is only available as a download to your computer. To get your download go to: