Brown led exposure system

[ABuffington]

My issue with all LED manufacturers is this:
Provide the histogram of the light. Both wavelength and watts (histogram) and proximity to surface.  Don't tell me what my emulsion is sensitive to, because you have no idea, we didn't provide you that info.  Many of these recipes of our sensitizers are trade secrets.

then take a 25T, and a 110T coated normally with any emulsion.  Expose an emulsion calculator image with no density overlay, just used for details at your best time.
Provide the times and show that when a white rag is wiped on the inside during development and screen is wet there is no emulsion color.
When there is no emulsion color showing, are all details visible?  All outlines, converging points, 12pt lettering and on the 110 halftones are showing, although they may moire a little.  Try to rub the image off during development.  Failure to avoid loss of details due to undercutting, or any imagery rubbing off is not a well exposed screen.  Anything done post in the way of post exposure or hardeners will never equal a well exposed screen.

Then set it up a production job with the best times for each mesh on an High Solid Acrylic ink print run and print 90,000 units.  While not many printers get these runs, this shows the major difference in LED vs MH.  One (MH) can already print 90k runs, the other will struggle and need lots of band aid work.  Again resolution of details has to be perfect, no slime or emulsion color can be rubbed off with a rag.  LED's have shown issues with thicker mesh and detailed stencils in this area.

I am an emulsion manufacturer, your histogram and wattage is all I need to know.  Absorbed Millijoules at proper wave lengths has to be sufficient to expose the emulsion correctly.  You can't bake bread by shortening the time and heat needed.  Same with emulsion, either bake it completely with proper UV light all the way through the emulsion or it will break down.  Emulsion likes Multi-sprectral output, it is not single spike exposure, multi-spectral lamps aid in the exposure process to achieve optimum strength.

Image is not the same as exposure.  I can expose any emulsion in ten seconds and get an image, but is it a strong image?

Plastisol can print almost any imaged screen ok.  But for discharge, HSA, and high end sim process where tonal control is important there are still unanswered questions regardind any LED system. 

Post exposure and hardening is just a band aid on underexposed screens, which LED often falls into, if the exposure can't go straight to screen, you aren't gaining a whole lot via post exposure on diazo and dual cures, some strength added for SBQ, but for screen strength strong light with a good calibrated reflector has not been beat yet in terms of durability. 

5 seconds?  What is the millijoules absorbed by the emulsion?  What mesh count?  What is the reading on the inside of the screen during exposure?  Not the lamp side?
That number on an LED is neglible.  On a 5kw metal halide, readable.

The LED's show great promise, and I have been impressed by a lot of units out there.  They will only get better and for some shops work very well already. But typically my tech calls involve emulsion breakdown.  50% are DIY shop lamps, 10% fluos,  40% for those that bought LED already but can't get both details and durability in one shot.   So this is all good dialogu,e would like to know more about all LED specs, but without a histogram we are working in the dark as emulsion manufacturers!   

Al

Alan

[Frog]

So this is all good dialogue would like to know more about all LED specs, but without a histogram we are working in the dark as emulsion manufacturers!
   
Don't tell me what my emulsion is sensitive to, because you have no idea, we didn't provide you that info.  Many of these recipes of our sensitizers are trade secrets...

Al

Do you see a disconnect here?
You, as an emulsion manufacturer want the specific light details, but can't give the light manufacturer your specific requirements.

[Orion]

 The recipe is secret, but it should be no secret that diazo/dualcure likes the lower end and SBQ likes the higher end. My Nu-Arc 6K range is listed at 300-450nm, we are covered no matter which emulsion I choose. I would doubt that there are any LED units that can cover that spectrum.

[jvanick]

can someone tell me why the chemical recipe emulsion uv sensitivity should be a secret??

-AND-

why the UV wavelength of LED exposure units should be a secret as well?

I for one would love to have an emulsion that closely matches my exposure unit as possible, I'd think that the combination of the 2 being 'suited' for each other would make for the best screens I could possibly expose?

[ZooCity]

My issue with all LED manufacturers is this:
Provide the histogram of the light. Both wavelength and watts (histogram) and proximity to surface.

Ditto. 

I agree with Frog, there needs to be some partnership/exchange between emulsion makers and LED expo unit makers for this tech to really fulfill it's potential.  We're just dipping into testing but it's obvious to me that LED needs emulsion made to respond to the LED array's output for it to truly surpass halide in any other area besides power consumption.  That or the LED arrays need to be as rich in multi-spectral light as a quality halide bulb.

[ZooCity]

can someone tell me why the chemical recipe emulsion uv sensitivity should be a secret??

-AND-

why the UV wavelength of LED exposure units should be a secret as well?

I for one would love to have an emulsion that closely matches my exposure unit as possible, I'd think that the combination of the 2 being 'suited' for each other would make for the best screens I could possibly expose?

We're both thinking and typing the same today! 

The trade secrets make sense.  As seen by those diy building, there is not excessive cost in the LED exposure machines if you have the right sources.   Same goes for emulsion, it's practically elmer's glue with some other stuff in it.  I can see why these parties protect their sources.  Seems like a partnership would be about the only way to bridge the issue.

[Orion]

Some reading for nerd types and/or others with time to waste...

http://www.google.com/patents/US20140038108

Is Louie the guy that came out with the "Baby Joe"?

[Frog]

He was posting here as Lou, so probably.

[Steve Harpold]

Hey Alan,

Thanks for the quick info, all the help I can get is great.

I am not sure though how it is possible to design and build an exposure system if the manufacturer is keeping the desired wave length (be it multi spectrum) a secret. There
 Are  many emulsion companies for us to work with that will post desired wave length and best intensity known to date.

So from a engineering side;
1. Since we cannot perform a 90,000 shirt test on every possible emulsions, we have chosen to work with manufacturers who are more transparent about the desired exposure  info.

2. If the emulsion company provides data about the relationship of speed as it relates to intensity than we can only hope that whichever exposure unit mfg company can generate the most intensity at the proper wavelength will create the best screen.  (Yes more goes into but simply stated)

3. At some point just cramming intensity probably with hit the limitations of the chemistry.  If these limitations are known it would be helpful for the emulsion company to provide the limitations.
            A. If they are not known than, as a exposure unit manufacturer I will continue to push the boundaries.

4.  If you can help with the following, it will make it easier to build an exposure system that makes the best use of your chemistry.

What wavelength do you recommend?

If using multi spectrum is better which wave lengths do you require and what is the best intensity at those wave lengths ?

If this proprietary than can you provide which elements make up the metal halide bulb you recommend? Or what metal halide bulb you recommend?

For a sales side:
1. Currently we have chosen to work with published numbers by other emulsion companies.

2. It is very hard for us to justify the tests you have listed as other companies provide the above information.

3. It is even harder if we have to first try to discover the wave length required to even begin developing or testing.

4. As we continue to push the envelope on LED technology,  it is important to us to make sure our product works with as many emulsion companies as possible, and also build products that work for the masses. If we find out product does not perform as listed with a certain type of emulsion or first reaction is to use an emulsion that publishes desired results.

5. If we receive a lot requests about a specific emulsion and find our system does not perform adequately the market will push us into working with that specific emulsion.

As it relates specifically to Alan:

Does you company currently list recommended wave lengths and intensities?

Is there a good contact to work with to obtain this information?

Thanks

[blue moon]

Some reading for nerd types and/or others with time to waste...

http://www.google.com/patents/US20140038108

Is Louie the guy that came out with the "Baby Joe"?

huh, this could be a problem for a few of the units out there. There seem to be some gaps open for the other manufacturers to get around, but some specs are pretty limiting.

pierre

[ABuffington]

The wavelengths are not a secret, we look at the spread from 350-420nm as an optimum area of UV wavelengths.  Multi-spectral across these wavelengths usually implies spikes in the 360-380 range and the 400-410 range.  The issue with LED's are they intitially were single spike wavelengths.  Multi spectral may consist of 2 spikes but little in between.  Metal halides achieve multiple spikes with the use of precious metals.  The percentage and specific precious metals used determines the wavelength(s) output of  the Metal Halide lamp.  With LED's this is not the case, they tend to be spike specific.  Glad to share specific data on wavelengths but for an LED manufacturer the question becomes how do we achieve amplitude (wattage) in nearby wavelengths.  They aid in the exposure process and resulting strength.  So the question remains, how do we get multi spectral output from LED beyond 2 spikes?

PM me for specific info on wavelength sensitivity.  I didn't mean to imply I won't share the wavelength info, this is pretty common in all emulsions, I just need to be careful on the sensitizers used as there are many which is proprietary info.

Al

[Orion]

An article from last fall pertinent to this discussion, specifically page 5:

http://www.screenweb.com/content/an-update-uv-led-screen-exposure?page=0%2C0