I Lowered Duv with a custom paint!

I think this idea held up to debate quite well. So let’s start an interest list. How many flashlight enthusiasts want a can of this Green Delete? It will be $15 for an 11 oz can. Which is not bad at all considering this is a specialty paint. And one can is basically a lifetime supply.

1) likevvi
2) id30209
3) aswang

Wow. Nice work Joshk. Very rosy tints are nice but I’m good with simple no green tint. I have a few lights that are just a little bit greenish for me and don’t want to put my remaining lee minus green on them. I’d definitely be interested in this paint of yours.

Some CTO or Amber paint to lower CCT might also be useful. I think these would be nice for diffusers for candlelight effect without sacrificing your favorite normal use CCT. Not sure if regular orange paint can achieve this without sacrificing CRI.

Thanks :+1:
Yea a CTO filter paint might be useful for painting a lantern-like dome for a night time attachment. Or just eliminating blue light in general.
If anyone is interested in seeing that happen, drop a comment.


I have SST-20 lights with FA3, FD2, FB4, 5000K, and one with a mixture of four different CCTs.

The light I tested with half-minus-green was FA3, so it was the best available SST-20 tint. FA1 would be better, but I don’t think anyone has managed to obtain those yet.

FA3 with half-minus-green looks pretty good on a white wall, and mostly okay during use, but I have to bump it up a step higher than other lights to get the same brightness. Also, it has some really weird effects on shades of pink and purple. It tends to make pink look more salmon-colored, and makes purple look less vibrant somehow, even compared to other 4000K LEDs.

The effect is strange. It seems to affect different colors in different ways. It’s most noticeable on items like this pink sheet:

The images are straight from the camera, and each one was white-balanced to the center of the beam on the white background before each shot. It’s a pretty good representation of how things look after one’s eyes have had time to fully adjust to each light.

The weird appearance of pink and purple doesn’t seem to be caused by the minus-green filter. It was doing the same thing before I put the filter on.

TK, have you considered buying a spectrometer?

You are over simplifying it but I see your point.

There are other tricks to reduce Duv but they come with tradeoffs. Note that I said turbo because people can relate to SST-20 and turbo as being a far different tint than it appears when on a very low setting. The truth is anytime the FET is predominant source of power it will happen too. So, you could take a nice 2 or 3 channel driver with some regulation and change it to a less efficient “FET only” 1 channel driver. You can still PWM a low(ish) setting but you will lose moonlight and have less efficient driver. However, it will be more uniform and lower Duv across the entire output range and you don’t sacrifice any brightness like a filter/paint/219b/frosted tir would.

Jon, I was referring to this:

And TK confirmed she has FB4, among others. She should really specify which bin she is filtering.

They all have to be driven pretty hard to ever get below BBL, even the FD2 found in your FW3A. So if you seek a LED which is below BBL I think the answer would be they are all bad :slight_smile:

Let’s not escalate.
And yes, I never use moon mode. I mostly use the ceiling.
I only mention turbo because anyone applying filter technology NEED to be aware of the dangers of 1/2 filters during Turbo. Many lights just use a fixed timer for turbo, and that would need to be re-programmed to run a 1/2 filter on turbo, or someone is going to get burned, or an emitter scorched.

I did.

This is probably good advice.

I was really hopeful that SST-20 could have its tint corrected to something more agreeable, but so far I’m finding that it’s still funky even after making it not-green. So I plan on getting some 219B 4000K LEDs to see how they compare.

Um, no. There’s just so many things with LED power lights or clock displays I can just walk around and see fine without a flashlight.

FWIW, another option for making SST-20 look good is to use it as a mule without any reflectors or optics. It looks really nice when it’s not focused.

For example, in one of maukka’s reviews, the forward part of a mule beam is at or below BBL even on a FB4 bin emitter:

BTW, I’m sorry Toykeeper for what I said.

That was a bit mean on my part.

I think our difference stems from our preferences.

I prefer something looking like sunlight as much as possible, so a bit of greenness isn’t bad to me. Perfectly neutral is of course the best.

Pinkish tints, though. Ugh. Not my taste.

Lets try to get this back on topic and set aside personal preferences.


  • did you use your paint on an already AR coated lens or plain glass? this may not matter but needs to be tested cause there are lots of different AR coatings or lack thereof and if people are going to spray lenses it would be good to test a few examples of both
  • how durable is the coating? does tightening it up against an optic leave marks on the inside?
  • any guesses if it will yellow or otherwise change color over time?

random thoughts:

TK has observed and SKV, myself and others have measured that an AR lens can actually raise Duv by a not insignificant amount. In some cases it’s almost non-existant (UCL) and in other cases it’s as much as (+0.002). An AR lens from an FW3A I measured was +0.0014 vs a plain glass. E07 was +0.002 according to SKV and +0.001 for a D4v2 AR lens

The AR coatings do not seem to effect the overall brightness very much but they do seem to be able to change the Duv by as much as what a 1/8 lee filter does. I wonder if there is any way to create an AR coating that would trend in the other direction or if this is just something ingrained in how these coatings work?

Yea mine appeared to be AR coated.
There aren’t any visible marks so far.
It shouldn’t yellow at all over time.

As far as AR coating raising Duv, based on your info, one coat of this stuff is perfect to reverse that effect.

Also noticed that SST-20 looks noticibly rosier and nicer with wide pebbled optics compared to clear narrow ones.

fyi, Jon and TK, I just scroll past your posts without reading them. Jon’s always read like hate-mail, and TK’s always tell me I do everything wrong and nothing right… in a sugar coated turd writing style.
But I can always count on you two showing up on any thread I start.

It’s true the thread-bumping effect keeps it in the recent posts, but it’s not worth it to me. There’s plenty of other intelligent members that can post politely.

For those interested, I started with a rosy/pink color like the lee filters. But it was cheating and lowering CCT, as well as not doing CRI any favors.
So I went for a slight shift toward purple and it was better.

This stuff is just a paint with a rosy/purple dye. Anyone with dye and a spectrometer could re-create it.
I am actually concerned the concentration of my dye has changed during storage, so once I am out I don’t plan to do this again. It’s not an issue for this batch, but it means the recipe is only valid until I need to restock.

Send me PM with payment details!