Blog articles about new related events and issues.

The Latest Information on the Hoya U 325C SW Filter

The following information is directly from Hoya Optics USA:

1. Will Hoya no longer be making the U 325C filter?

We are developing an alternative glass for the current U325C.

2. Hoya is trying to make that filter but at a different location (you told me that earlier). But the information says that Hoya is having problems producing that filter, is that true?

The company which has been melting U325C has decided to stop melting this glass. Hoya is trying to develop an alternative at a different location. Before the development is complete, we cannot say how different the alternative is compared to U325C.

3. Hoya will only be making the 6.5 inch square size of the U-325C filter not any larger sizes, is that true?

This is under our consideration, but not concluded yet.

4. Hoya will only make polished U-325C filters (I assume thinner than 4.5 mm), is that true?  If Hoya will be making that filter as molded what thickness will it be?

If Hoya will be making that filter as molded what thickness will it be?
This is under our consideration, but not concluded yet.

Some additional questions:

a. Is it expected that the price of the new Hoya U-325C filter will be more expensive than in the past?

Yes. The price will be more expensive.

b. Will the exact same formulation be used for the new U-325C filter?

The alternative of the exact same formulation is also under developing.

c. Will the solarization rate after exposure to 253.7 nm UV be the same for the new U-325C? Will Hoya conduct solarization tests on the new and old U-325C to compare the difference if any?

We don’t want to assume the solarization rate until the test is done. Hoya will consider conducting solarization test on the new alternative.

d. Additional I would like to know, if Hoya will be continue to make that filter when can orders be placed?

We are trying to launch it in Oct. 2019 as the earliest.


Solarization of SW Filters

UV SYSTEMS, Inc. has new data on the solarization of SW Hoya Optics U-325C filters. The Smithsonian Institution National Museum of Natural History has two fluorescent mineral displays in which they use UV SYSTEMS, Inc. SW TripleBright II model FSLS UV lights. Because of solarization the Smithsonian normally replaces the filters in their UV lights about every year.

They recently sent UV SYSTEMS, Inc. two filters from one TripleBright II to have their transmission measured. We know when those filters were installed and when they were removed, and because they turn “on” and “off” their fluorescent displays at the same time every day (except Christmas) we can calculate the exact number of hours those two filters were exposed to SW UV. Those two SW FS-60 filters were exposed for exactly 5695 hours. Those used filters had a transmission of 21.2% for one and 25.1% for the other.

UV SYSTEMS, Inc. usually recommends that SW filters be replaced when their transmission is below half of what a new filter would be (between 28.5% and 30% transmission). New FS-60 filters have a transmission of about 56.9% to about 60% at 253.7 nm (SW). Based upon the Smithsonian data, SW filters used in a SW TripleBright II or TripleBright 3 UV lights should be replaced about every 4900 hours.


The Improved B3 battery pack is now less expensive!

B3 Battery & Charger

Now called the B3 by adding more padding to the blue nylon bag. Yet we have been able to reduce the price due to some of price reductions in the parts of the B3. The B3 is now more than 18% lower in price than the B2. The complete B3 with battery, bag, strap, coiled-cord, and charger is now only $163.00 plus Shipping and Handling. Shipping and Handling within the USA is $22.65.

Check it out!


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 two sizes. These are 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 3, and Dual TripleBright 3 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 3 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 3 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 3 is only $772.00 plus S&H of $22.65 within the USA. First come first serve, only one is available.

This SW TripleBright 3 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 3 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 3 model FSLS from our store, but in the comment section write “I want the used SW TripleBright 3 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. 26th Year in Business

UV SYSTEMS started as a sole proprietorship in Feb. of 1992 and became incorporated in Dec. of 1999. We have over 3000 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: