# bulb for exposing emulsion



## shirtsari

This post is to help newbies. I too was a newbie just about a month ago.

Every bulb produces UV light, some more, some less. I have burned many screens with a regular frosted 60 watt incandescent bulb about 12 inches from the screen. I turned it on before bed and then when I woke up the image washed out of the screen perfectly. (I haven't tried half tones yet.)

I just use running tap water and a soft brush to wash out the image after wetting it and letting it sit for a few minutes. You DO NOT NEED a pressure washer. Just be sure your emulsion is fully dried to the interior (use a fan till the surface is dry and then let it sit in a dark place overnight to be sure. You can use a heater to speed up the process but don't put it too close, heat can "expose" the emulsion) and that you expose your screen long enough.

I have a 500, 250, 150, 100 and 50 watt halogen lights but up to now I mostly use the sun or a 200 watt clear incandescent bulb. I still have to experiment with the halogen lights.


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## RespecttheCraft

i use a 500w metal halide lamp suspended about 20" above my screen and a peice of glass to hold the positive to the screen. works great, plus having a point lightsource gives crisp lines and excellent halftone definition. when i was starting out i used a 100w HPS unit that used to be an outside security lamp. worked well for definition and whatnot but took about 30 min to expose!!


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## shirtsari

Thanks Matt I will keep my eye out for a Metal Halide lamp. I will also check it out on the internet.


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## Bob Wellen

With all do respect, these bulbs work but tend to cause more issues than it is worth discussing.The whole idea behind exposing emulsion is completely expose it as fast as possible so you can hold resolution. the longer the ligh is on or the weaker the ligh source, the more undercutting you get and the image tends to get very ragged from the length of time you are exposing. It is very important to get the coating thickness right and and the exposure to be complete. The idea of underexposing a screen to hold cvopy does not hold water. If you are just starting a shop, the first thing to look at is an appropriate light source before you buy anything else. You have to be able to make good quality screen to be able to print well. Direct emulsion are geneally rated between 360 to 420 nanometers. Try Bulb tronics or Western quartz for a bulb that has that wave length or jump to a metal halind lamp which is basically todays best lamp.


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## bluemoon

Bob Wellen said:


> With all do respect, these bulbs work but tend to cause more issues than it is worth discussing.The whole idea behind exposing emulsion is completely expose it as fast as possible so you can hold resolution. the longer the ligh is on or the weaker the ligh source, the more undercutting you get and the image tends to get very ragged from the length of time you are exposing. It is very important to get the coating thickness right and and the exposure to be complete. The idea of underexposing a screen to hold cvopy does not hold water. If you are just starting a shop, the first thing to look at is an appropriate light source before you buy anything else. You have to be able to make good quality screen to be able to print well. Direct emulsion are geneally rated between 360 to 420 nanometers.


thanx Bob! I'll second this.


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## BroJames

They will find out sooner or later that, generally, faster exposures does not only mean a shorter waiting time but better exposures as well. I would suggest the thread starter to continue his/her exposures with nothing less than a 500w halogen lamp. 

Start it right. A 500w halogen lamp is still not right but is a good starting point.


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## Bob Wellen

No problem. always available to help.


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## xucaen

I've been seeing videos on YouTube that seem to suggest that I can expose a screen with a regular 60 watt bulb in about 10 minutes. Can someone please help?


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## NoXid

xucaen said:


> I've been seeing videos on YouTube that seem to suggest that I can expose a screen with a regular 60 watt bulb in about 10 minutes. Can someone please help?


As others said above, such a light can work, but leaves a lot to be desired. 10 minutes .... _maybe_ with a very fast poly emulsion, but would be longer than that with Diazo emulsion. If they have the bulb close enough to the screen to expose that fast, it would probably be an uneven exposure (under exposed at the edges).

The sun is much better in terms of quality, and speed, than any of the inexpensive methods. I know a graphic artist who used nothing else, ever. Experiment with this if you want a cheap easy method that gives results as good as the most expensive single point light source (the sun being the perfect single point light source).


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## xucaen

It's this the bulb I need?

http://www.amazon.com/gp/aw/d/B005P...row+lights&dpPl=1&dpID=41X4jMnJ7yL&ref=plSrch


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## Printor

If I remember right, The sun is about 300w per square foot. You can grow plants with a 60watt bulb, but they will be very sad looking and not produce the desired effect


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## xucaen

Yup that's actually 250 watts plus I just found the page in Scott's book where he says to use a grow bulb.Thanks!


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## NoXid

xucaen said:


> Yup that's actually 250 watts plus I just found the page in Scott's book where he says to use a grow bulb.Thanks!


Watts is a measure of power consumption, not of light output, and especially not of UV light output ... though it is often used as a proxy for light output when explaining how much "light" a fluorescent bulb makes since people are used to thinking in terms of watts and incandescent bulbs.

I made my first screen in the early '90s with a 250 watt incandescent in a clamp-on reflector. It worked. Just don't expect to be burning detailed halftones 
Keep the emulsion coat thin, or the back side will be a gooey mess.


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## xucaen

The description says it is a 5500k daylight output bulb.


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## RichardGreaves

xucaen said:


> The description says it is a 5500k daylight output bulb.


That's lots of visible light for illumination. 

The only energy that reacts stencil sensitizers is INVISIBLE UV energy in the 380 to 420 nano-meter range. UV-A.

Search for sources with output in the UV-A range.


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## xucaen

RichardGreaves said:


> That's lots of visible light for illumination.
> 
> The only energy that reacts stencil sensitizers is INVISIBLE UV energy in the 380 to 420 nano-meter range. UV-A.
> 
> Search for sources with output in the UV-A range.





 5500K day light energy balance photo light bulb 5500K
 Optimal color temperature for hydroponic
 Approximate Incandescent Equivalent: 250 Watts
 60 Watt CFL Full Spectrum Bulb


So basically what you are telling me that "5500k" and "CFL full spectrum" have absolutely nothing to do with UV?? Even through all reliable sources say to use CFL full spectrum lights and Scott Fresener says to use "grow lights", which this certainly is.


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## Printor

I'm using a 1000w MH grow bulb, But it has led in the outer glass housing, which has to be blocking some UV extending my time some but I have my times wired and don't want to mess with a good thing right now. The led content in the glass top will block some UV as well. next time you break it, tell your glass guy the lower the led content the better.


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## RichardGreaves

*UV energy source to cure stencils*



xucaen said:


> 5500K day light energy balance photo light bulb 5500K
> Optimal color temperature for hydroponic
> Approximate Incandescent Equivalent: 250 Watts
> 60 Watt CFL Full Spectrum Bulb
> 
> 
> So basically what you are telling me that "5500k" and "CFL full spectrum" have absolutely nothing to do with UV?? Even through all reliable sources say to use CFL full spectrum lights and Scott Fresener says to use "grow lights", which this certainly is.


Yes.

Full spectrum lamps that mimic sunshine is 95% wasted energy. Sure, even 5% will start to cure your stencil. You've read how even incandescent lamps can _*work *_.... eventually.

Speed costs money. How fast do you want to go? Weak UV-A is slow and sure, but slow. Slow means more time for light scatter and undercutting.

I will discuss this with Scott on the next T-Shirt Report we record on August 10th and report sooner here what Scott meant.

==========================================
12:20a

page 14 of How To Print T-Shirts for Fun and Profit

*What Light Sources Contain UV Rays?*
"Sunlight contains an abundance of UV light
compared to some plant "grow-lights" and backyard
quartz and work lights that produce much
smaller amounts of UV output. Professional
screen-exposing units contain light sources that
are high in UV output."

Sun - lots of usable UV
Grow lights & quartz halogen lamps - not so much

Weak. They have some, but they're at the low end of the output range.

This is what Scott wrote, and I agree. Grow lights are low energy output.


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## xucaen

You're trying to tell me that light bulb won't work. I think it will work. Fast?? I never said anything about Fast. I just want something - anything - that will work. Tell Scott his book is very confusing.


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## NoXid

xucaen said:


> You're trying to tell me that light bulb won't work. I think it will work. Fast?? I never said anything about Fast. I just want something - anything - that will work. Tell Scott his book is very confusing.


"Fast" is not just about speed, it also affects quality. In this case faster produces better quality and easier to work with screens.

Yes, almost anything will work. But you are likely to get more undercutting and inadequate penetration of the emulsion with weak UV sources. Inadequate penetration is frustrating to deal with. If you must use a weak UV light source, use a fast Poly emulsion, else you will probably be frustrated with the results.

The sun is FREE and better in quality of results than _any_ cheap light source, and many expensive ones. <-- Start here if you just want to give it a try without investing in equipment. Your results will be better than commercial UV fluorescent units. Use a slow Diazo emulsion so you have more margin for error.

^ Neither of the above are expensive to try, so just do it and learn for yourself.


Regarding Metal Halide. These produce a smallish percentage of UV light, but they produce _so much_ total light that the actual quantity of UV light is large. MH bulbs either filter out UV or are intended to be place in a fixture that filters out UV. To build a MH unit, one uses a non-filtered (unprotected) MH bulb with only a piece of low iron (UV transparent glass) between it and the art. My DIY 1000w MH unit exposes Poly emulsion in 25 seconds. The image comes out crisp and clean. No undercutting. No gooey unexposed emulsion on the back side of the screen. No frustration.

NOTE Looking at an unprotected MH bulb will damage your eyes. Strong sources of UV light are dangerous, and will not be found hanging over your grandma's potted plant 


So go ahead and do it the cheap or free way and see if you even like screen printing. If you decide to go further, then buy/build better equipment. Most of us started with cheap/inadequate methods/equipment, just realize that certain frustrations and quality issues go hand and hand with that and that you can make them go away by upgrading.


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## RichardGreaves

xucaen said:


> You're trying to tell me that light bulb won't work. I think it will work.
> 
> Fast?? I never said anything about Fast. I just want something - anything - that will work.
> 
> Tell Scott his book is very confusing.


I have never, never, ever told you or anyone else *it won't work*. I don't know about your circumstances, so I'm in no position to tell you what you should or shouldn't do. I spend time helping you and every other person that reads my posts make an educated choice about a UV-A energy source.

*You *wrote "Scott's book where he says *to use a grow bulb*." bold by Greaves

He didn't write that. He *compared *the sun to "grow-lights and backyard quartz and work lights that produce *much smaller amounts of UV output*"

I *did *write, "You've read how even incandescent lamps can work .... eventually." I wrote earlier how I think it's a mistake to invest in _'inefficient for UV energy_' sunshine reproducing lamps, designed for plants, because there are other lamps that output more UV-A energy and plants take *MONTHS TO GROW*.

I explained the science of how sensitizers join. I explained why *faster curing* renders better fine lines. 

You are mis-quoting me , AND as I wrote last night, you're mis-quoting Scott Fresener.


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## xucaen

I just wanted to follow up in case any new people are searching for a light bulb. That bulb works perfectly! It exposed my screen in about 20 minutes and left a perfect stencil on my screen. So if you are new and are looking for a light bulb to expose your screens, that is the bulb to get. Don't let the nay sayers discourage you as they almost discouraged me. Peace and long life. \\//,


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## Dolcedoja

xucaen said:


> I just wanted to follow up in case any new people are searching for a light bulb. That bulb works perfectly! It exposed my screen in about 20 minutes and left a perfect stencil on my screen. So if you are new and are looking for a light bulb to expose your screens, that is the bulb to get. Don't let the nay sayers discourage you as they almost discouraged me. Peace and long life. \\//,


what bulb works perfectly????
every single reply spoke on about 5 different types


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## RichardGreaves

I'm assuming you don't mean perfect even thought that's what you wrote.

Curing a stencil is like filling a bucket with water. Hundreds of sources will work, but each takes a different amount of time. A medicine dropper takes longer than a garden hose or a fire hose to fI'll the sAmerican bucket. Weak 40 watt fluorescent lamps have poor penetration but are inexpensive. 

There's also a difference in the speed of your stencil material. Some are slow, some fast.

This is why there's a range from $1 work lamp bulbs in a $15 fixture to units that cost $10,000. As the drag racers say, "Speed costs money. How fast do you want to go"?

The best graphic UV exposure lamps come from Olec or Nuarc. An inexpensive work lamp with a quartz halogen incandescent bulb can be found at Lowe's or Home Depot for $15 and takes 10-30 minutes to cure fast reacting photopolymer stencils like Saati PHU2 or Ulano QTX.

If you buy a worklight, remove the UV safely glass designed to protect your eyes.

Answer back and tell us what perfect means to you.


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## sben763

RichardGreaves said:


> The best graphic UV exposure lamps come from Olec or Nuarc. An inexpensive work lamp with a quartz halogen incandescent bulb can be found at Lowe's or Home Depot for $15 and takes 10-30 minutes to cure fast reacting photopolymer stencils like Saati PHU2 or Ulano QTX.
> 
> If you buy a worklight, remove the UV safely glass designed to protect your eyes.


 Except neither on of these companies make their own bulbs. Ushio makes great graphic bulbs and I believe they are the main supplier to the industry under the 3 names the sell bulbs under. 

Buying a standard work light (halogen) will work but not all halogens are created equally. Halogen lights can contain Bromine, Iodine, or other inert gasses that will change the UV output and the spectrum it will peak in. A everyday halogen will put out very little usable UV light (365nm-410nm) vs a photo halogen which will put out 10- 25 times or more the usable UV light depending the make up of the bulb, this goes for Metal Halide bulbs but these use metals to create the different outputs.


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## fhobart

It has been mentioned that emulsion reacts to UVA. I found a site that has bulbs that produce UVB and some that radiate UVC--to kill those nasty viruses.

Would these be any better/faster than UVA bulbs? Is there a better/fairly inexpensive option that I've missed? Thanks in advance.


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## NoXid

fhobart said:


> It has been mentioned that emulsion reacts to UVA. I found a site that has bulbs that produce UVB and some that radiate UVC--to kill those nasty viruses.
> 
> Would these be any better/faster than UVA bulbs? Is there a better/fairly inexpensive option that I've missed? Thanks in advance.


Each emulsion has a spectrum to which it is most reactive. I would be surprised if any were tuned specifically to the germ exterminating spectrum. I would also be surprised if those special-purpose/limited-market bulbs were cheaper than others.


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## RichardGreaves

fhobart - The answer is in your question, is right there in your question.

Pre-sensitized photopolymer stencils sweet spot is 405nm. Diazo, 370nm ish.

This means UV-B & UV-C might have some weaker UV-A energy, just as many household bulbs do. Given enough weak low energy exposure, you will eventually cure your stencil.

Furthermore, UV-B & UV-C are much more dangerous to your skin & eyes so I want you to avoid them.


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## sben763

RichardGreaves said:


> fhobart - The answer is in your question, is right there in your question.
> 
> Pre-sensitized photopolymer stencils sweet spot is 405nm. Diazo, 370nm ish.
> 
> This means UV-B & UV-C might have some weaker UV-A energy, just as many household bulbs do. Given enough weak low energy exposure, you will eventually cure your stencil.
> 
> Furthermore, UV-B & UV-C are much more dangerous to your skin & eyes so I want you to avoid them.


The Presenitized emulsions vary greatly according to the manufactures. 405nm is Saati Chem Presenitized where as some Ulano are 365-375 if I remember right. I'd have to pull the emails to be sure. Murakami I think advised 385-395. Chromaline for the most part was 395nm. I may have switched a few around but while developing exposure unit I emailed and tested almost every manufacture that responded. 

The diazo ranged from 365nm-380nm compared to the 365-405 responses I received for pure photopolymer. In another forum I asked one of the manufacture reps why the great differences. His reply was we all use different sensitizers or blends of sensitizers and most are kept trade secrects. Most diazo are dual cure so the diazo is 365-370nm but the range comes from photopolymer element of the dual cure. 

UVA can also be damaging to your eyes. Some spectrums in the UVB and UVC can blind a person in a matter of seconds to a few minutes depending on the intensity.


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## Printor

Stupid Question Do good UV sunglasses help with A, B, and C?


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## sben763

Printor said:


> Stupid Question Do good UV sunglasses help with A, B, and C?


Polarized lenses. They don't have to be expensive. Even a thicker lens doesn't help as the contain the same polarization film. Thick lenses are only beneficial for impact protection. But yes all polarized lenses will greatly reduce the effects of UV A,B,C. They also make glasses that have a double polarization film and another filter for high intensity UV like those used in leak detection, forensics and germicidal lamps.


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## theblueguy

sben763 said:


> Polarized lenses. They don't have to be expensive. Even a thicker lens doesn't help as the contain the same polarization film. Thick lenses are only beneficial for impact protection. But yes all polarized lenses will greatly reduce the effects of UV A,B,C. They also make glasses that have a double polarization film and another filter for high intensity UV like those used in leak detection, forensics and germicidal lamps.


Hello,

I have taken quite a number of information about the methods and the science of exposing a screen from your posts, and if you do not mind, I would like to ask you about my low budget exposure set up.
I have been looking to create my own starter exposure unit, and was interested in using the speedball light kit that uses a 250 watt photo flood bulb and a reflector lamp.
With my set up I will be using a large reflector lamp and a 250 watt quartz halogen bulb, with Diazo speed ball emulsion.
My designs will e simple and not feature any halftones.
Before I have experimented with a standard cfl bulb with an exposure of 30 minutes and I overexposed and underexposed the screen,as only a faint and smudged design had managed to get through.


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## socceronly

Question regarding undercutting.

Why does the exposure time matter? If you are using a weaker light, with a longer exposure time, wouldn't the amount of light doing the undercutting be directly proportional?

Why wouldn't a brighter light simply mean more light doing the undercutting for a shorter time.


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## socceronly

I also found this bulb, it says blue shifted and the spectral graph looks good. 

Apologies if it was already posted.

Ultra Sun® Metal Halide Blue Enhanced Performance Lamps | Ultra Sun Lamps


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## fhobart

I took a look at the Ultra Suns; am I wrong, or do these appear to fit in standard fixtures? Currently, I am using the Nazdar ProChem LXP LED optimized emulsion (https://sourceone.nazdar.com/P/4413/ProChem-LXP-LED-Optimized-Emulsion) and a dual bulb set up with the Ryonet DIY bulbs (ScreenPrinting.com | Powered By Ryonet -). I have used both regular transparencies (laserjet) and vellum with the bulbs 12" away centered. I primarily use 110 mesh and have exposed anywhere from 9 minutes to 15 minutes with mixed results. I am having huge issues with thin lines and smallish text. Neither washes out easily and when I continue spraying, detail is lost. 

I am a high school engineering teacher in charge of my school's competitive FIRST robotics team. We use t-shirt sales as a major fundraiser (beats candy bars) and I need to improve my screen making. This is not my primary vocation, so I am not nearly an expert....thanks in advance.

Will the MH bulb solve my problems?


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## Printor

fhobart said:


> I took a look at the Ultra Suns; am I wrong, or do these appear to fit in standard fixtures? Currently, I am using the Nazdar ProChem LXP LED optimized emulsion (https://sourceone.nazdar.com/P/4413/ProChem-LXP-LED-Optimized-Emulsion) and a dual bulb set up with the Ryonet DIY bulbs (ScreenPrinting.com | Powered By Ryonet -). I have used both regular transparencies (laserjet) and vellum with the bulbs 12" away centered. I primarily use 110 mesh and have exposed anywhere from 9 minutes to 15 minutes with mixed results. I am having huge issues with thin lines and smallish text. Neither washes out easily and when I continue spraying, detail is lost.
> 
> I am a high school engineering teacher in charge of my school's competitive FIRST robotics team. We use t-shirt sales as a major fundraiser (beats candy bars) and I need to improve my screen making. This is not my primary vocation, so I am not nearly an expert....thanks in advance.
> 
> Will the MH bulb solve my problems?


I'd try a higher mesh screen 125-156 before changing my light source. While I have my times somewhat figured out. If you post a pic of an image you can't achieve with a 110, that will help people suggest the proper mesh.


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## RichardGreaves

*Re: Question regarding undercutting*



socceronly said:


> Question regarding undercutting.
> 
> Why does the exposure time matter? If you are using a weaker light, with a longer exposure time, wouldn't the amount of light doing the undercutting be directly proportional?
> 
> Why wouldn't a brighter light simply mean more light doing the undercutting for a shorter time.


Yes, yes, yes!

Novice screen makers have used UNDER exposure as a remedy for undercutting and light scatter. UV energy from *any *source other than the sun strikes the surface of the stencil at an angle. You are letting the results control you, rather than making some changes to get the result you want.

If you need to print fine lines or halftones, that's your most important goal - reproduction, and that starts with the art department making decisions in design rather than exposure and washout tricks or magic ink or sorcerer's squeegee waved across the top. 

Even the best single point UV source strikes all four corners of your stencil at an angle, and sneaks under the positive or DTS image. The UV energy bounces around in the jungle of stencil components and rounded mesh, scattering it, out of your control, in every direction.









UNDER cured, *medium-rare stencils* fail because solvents can freeze it in the mesh or water-based inks can eat away at the raw inside of the stencil.

With careful washout and non-solvent inks like most plastisols - it can work. Just as we learned to compete with Mother Nature's gravity when we throw a ball a long distance or through a side wind, we need to adjust and compensate to get the results we want. 

Under cutting is inescapable. The sooner you learn to anticipate and compensate for the choking of fine lines and halftones in the art department, the sooner you can have durable, *cured* screens that can reproduce the resolution you desire.

More powerful UV sources have more power to penetrate a stencil and cure faster, but power has no effect on undercutting and light scatter. Thicker stencils with low energy exposure equipment may not cure the stencil all the way through. Imagine cooking a pancake or a hamburger and not flipping it over. Time will not solve that problem, you must have penetration. 









After washing out the image area, feel the screen on both sides with your fingers. If the texture of the stencil is slimier/stickier/different on the inside compared to the bottom, UV energy didn't penetrate and the inside is under cured.

Light scatter can be minimized with dyed mesh that absorbs rather than scatter UV energy, but it also takes longer to cure.

Novice screen makers have used UNDER exposure as a remedy for undercutting and light scatter. UV energy from *any *source other than the sun strikes the surface of the stencil at an angle. You are letting the results control you, rather than making some changes to get the result you want.

Even the best single point UV source strikes all four corners of your stencil at an angle, and sneaks under the positive or DTS image. The UV energy bounces around in the jungle of stencil components and rounded mesh, scattering it, out of your control, in every direction.

UNDER cured, *medium-rare stencils* fail because solvents can freeze it in the mesh or water-based inks can eat away at the raw inside of the stencil.

With careful washout and non-solvent inks like most plastisols - it can work. Just as we learned to compete with Mother Nature's gravity when we throw a ball a long distance or through a side wind, we need to adjust and compensate to get the results we want. 

Under cutting is inescapable. The sooner you learn to anticipate and compensate for the choking of fine lines and halftones in the art department, the sooner you can have durable, *cured* screens that can reproduce the resolution you desire.

*Under cured means harder stencil removal*
The invisible consequence is that your stencil is UNDERcured and development alters the balance of molecules so *sticky polyvinyl acetate* can stick permanently to the mesh and stencil removers don't work. This is the same problem we face if we let stencil remover dry on the mesh. Only a knife can get the stencil out.

Emulsion is glue. Take two small scrap pieces of wood and rub some emulsion on then and stick them together. You will see they are bonded together tomorrow.


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