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Discussion Starter · #1 ·
Hello, I changing everything to led in my shop ( i know exposure units use specific wavelength led's to produce
the uv light needed in the exposure process.) This is for the back side of my washout booth when Im washing out the image. I have read that standard cool white 4000k leds ( even 5000k ) do not emit UV light ( or enough to affect the emulsion once in the solid state. AGAIN THIS IS NOT FOR INSIDE MY EXPOSURE UNIT, WHICH IS MY NEXT PROJECT TO TRY AND CONVERT MY Luminar exposure florescent unit to a led set up, would be great if they would sell the led panels and parts to ungrade the cabinet as my vacuum runs perfect and just replaced my neoprene mat ( best part replacement that I ever made since 1997)
ok back to the point at hand, do I need the amber uv filters on the led light mounted behind my washout booth. I attached 2 booth images without the filters, then also the led lights I converted as shop lights ( also heard that they shouldnt affect the coated emulsion
Thank you for all info and advice and experience in advance
all lighting shown is led


Purple Rectangle Wood Fixture Pink
Wood Gas Tints and shades Window Machine
Automotive lighting Tints and shades Circle Electricity Symmetry
Fixture Electricity Sunlight Tints and shades Circle
Building Font Electronic instrument Darkness Metal
 

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I have read that standard cool white 4000k leds ( even 5000k ) do not emit UV light ( or enough to affect the emulsion once in the solid state.
They do emit enough to cause issues with fast exposing emulsions, especially when the distance is small, or the LED used is very bright.
For the washout booth, a transparent yellow film in front of the light will fix the issue.
 

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Discussion Starter · #3 ·
They do emit enough to cause issues with fast exposing emulsions, especially when the distance is small, or the LED used is very bright.
For the washout booth, a transparent yellow film in front of the light will fix the issue.
i do have several extra 4 foot amber filter tubes that I can cut down then slit the backs to wrap around the intergrated bulbs ( they dont remove) other then that what types of film do they make for uv blocking purposes? I typicaly do 2/3 of washout without the lights on, then the last part the fine details and final check I have the lights on

thanks for your info, oh I am using ChromaBlue emulsion
 

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i do have several extra 4 foot amber filter tubes that I can cut down then slit the backs to wrap around the intergrated bulbs ( they dont remove) other then that what types of film do they make for uv blocking purposes?
Any transparent yellow, orange, or red film will do.
Blocking the other wavelengths is what gives them their color.
 

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Discussion Starter · #5 ·
i also have a sign shop and used to have the yellow / red adhesive back film but not sure if I have anymore.
I may take a screen with emulsion on it and put a film in front of it for 15 minutes then block that section and leave the rest of film in front of the light behind the booth for an hour, then do a test washout to see what actually exposes in front of that led with the booth white plastic between it, if it goes bad, then Ill slit the back of the amber tube filters and wrap them around the bulbs ( since the led tubes are intergrated) ill post results
 

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I may take a screen with emulsion on it and put a film in front of it for 15 minutes then block that section and leave the rest of film in front of the light behind the booth for an hour, then do a test washout to see what actually exposes in front of that led with the booth white plastic between it, if it goes bad, then Ill slit the back of the amber tube filters and wrap them around the bulbs ( since the led tubes are intergrated) ill post results
I like experiments, but I already know yellow films work.
You may as well try a screen without any film and see if that LED emits enough UV light to cause issues.
Use a piece of cardboard and uncover 1/4 of the screen every 5 minutes or so. Leave the last section unexposed to use as a reference.
Then try washing the screen and see if the exposed parts have cured at all.
If not, then you don't need any UV blocking.
 

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Discussion Starter · #7 ·
I performed the test as you described, the light is from harbor freight ( as my home depot one died withing 2 days. The light specs are 7000 lumen 2ft length 4 bulbs 4000K 70 watts per bulb ( motion sensor turned off) I will attach picture
I used cardboard and tape and had the top section not covered during the test, then after 5 min I removed 4-5" of cardboard & tape, then at the 10 min timer I removed another 4-5" of cardboard & tape, then I went to 20 minutes and removed 4-5" of cardboard & tape, finally at 30 min I removed the rest of the cardboard and tape including the botton 4-5 " that was blocked through the whole test.
Then I washed out the screen with my smaller detail nozzle ( not a standard garden hose handle) the nozzle I used takes 7 minutes to fill 2 gallons of water ( I recently tested that 2 weeks ago when deciding which mini tank electric water heater i wanted to use for my washout booth as my booth hoses was putting out anywhere from 42-50 degree water and I was having washout issues) the water temperature during this test was set at 78 degrees and really low pressure.
In conclusion, the 30 minutes of direct LED 7000 lumens ( but probably not that accurate) and a distance of no more then 5" separation from the light and the screen ( just the translucent white when new) washout booth back wall had ZERO curing properties to the ChromaBlue emulsions that I used. The emulsion was applied 1 coat on the shirt side and 1 coat on the squeegee on a 195 screen. So it appears atleast 4000k LED lights with no filters will not affect my emulsion during my washout process.
attached are pics and a timelapse of the washout ( but really didnt need timelapse as it washed the uncured emulsion faster then I thought

VIDEO LINK IS HERE
WASHOUT SCREEN USING NON FILTERED LED LIGHT IN BOOTH
 

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In conclusion, the 30 minutes of direct LED 7000 lumens ( but probably not that accurate) and a distance of no more then 5" separation from the light and the screen ( just the translucent white when new) washout booth back wall had ZERO curing properties to the ChromaBlue emulsions that I used.
Good result, but everyone trying it should do the same test... Just to be sure.
 
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