# Overexposed or Underexposed?



## Lilinoe (Jun 17, 2008)

how do I know if my screen is overexposed or underexposed?


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## Tj Ryonet Tech (Jul 28, 2008)

Overexposure : your image won't wash out at all or the lines will appear jagged on the image
Underexposing: your image and the emulsion will wash out easily or you will have a layer of "scum" still on the screen


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## RichardGreaves (Nov 7, 2006)

Lilinoe said:


> how do I know if my screen is overexposed or underexposed?


As a screenmaker, your first job is to harden the stencil so it doesn't dissolve with water. UV energy needs to move all the way through the stencil to the back to completely harden the stencil.









I want you to put a Stouffer 21 Step Transmission Scale on every screen you ever make for the rest of your life. Expose so you get a solid step 7. You get visual feedback that is the best monitor I know.

They only cost US$6 to US$12 depending on where you buy and properly used, it should last a lifetime.

Then you need to calibrate your designs so that fine lines don't get choked because UV energy can bend and scatter in the stencil making the small openings - smaller. 

It may be that you have to make 0.020" lines 0.030" in your computer, so that they finally print at 0.020".

Exposure FAQ of Screen Making Products


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## madaradio (Nov 12, 2007)

RichardGreaves said:


> As a screenmaker, your first job is to harden the stencil so it doesn't dissolve with water. UV energy needs to move all the way through the stencil to the back to completely harden the stencil.
> 
> 
> 
> ...


great post. Where might I be able to buy a Stouffer 21 Step Transmission Scale? I want to try this.

edit: I found an old post of your where you listed a few places. Thanks!
http://www.t-shirtforums.com/screen-printing/t11860.html#post219000


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## RichardGreaves (Nov 7, 2006)

Internet Sources for Stouffer 21 Step Sensitivity Guide

Video on making a Stepped Exposure Test and other videos
Support Menu of Screen Making Products

Link to the Screen Maker Exposure Kit at Lawson Screen & Digital
Screen Maker Exposure Kit - 301-900-0-KT
Exposure Calculator for deciding how fine a line you can achieve with your stencil, mesh and exposure.

Separately:
Here is the link to the 21 Step Gray Scale
21 Step Sensitivity Guide - 301-905-1-EA

Below, find the Ulano One Step exposure calculator
21 Step Sensitivity Guide - 301-905-1-EA


*T2115 Stouffer 21 Step Sensitivity Guide distributors*
*Stouffer itself*
Mishawaka, *IN *46544 574-252-5772
Product and Price list

Graphic Arts Supply Hobart, *IN* 46342
STOU21 Stouffer 21 Step Platemakers Exposure Guide - $9.28 : Graphic Arts Supply, Online Store

Cape Fear Press Carolina Beach, *NC *28428 USA
910/458-4647
Puretch photopolymer go to the bottom of the page

Blue Hills Printing Ink and Litho Supply Corp. $6.53
Wisconsin Dells, *WI
*Blue Hills Printing Ink and Litho Supply Corp.

American Printing Equipment & Supply Co.
Elmont, *NY* 11003 $7.50
21-Step Sensitivity Guide - HTC134

PressmansPride.com *CA * Sacramento, Ca 95822
Fully Stocked Distribution Centers: Chicago, *IL* 60017 Gardena, CA 90248
21 Step Stouffer Scale

Bostick & Sullivan $11.00 Santa Fe, *NM* 87507-9743
505/474-0890
Bostick-Sullivan :: Beakers, Graduates, Thermometers & Droppers :: Step Wedges - 21 Step Transmission :: Step Wedge - Uncalibrated

Transmission Step Wedge Numbered ½" X 5" Unit Price: 15.95
21 Step Sensitivity Guide 09-0325
Product Details



I would love to hear of other reliable distributors.

Richard Greaves
Direct line 718-943-1338


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## JAGGER72 (Jan 22, 2010)

what are the factors the determine exsposer times?


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## RichardGreaves (Nov 7, 2006)

*Factors that determine exposure*

*Measuring Exposure*
It is fundamental that a screen must survive development. With all the variables of screen making that can effect durability & reproduction, complete exposure/hardness/cure is the minimum skill for the screen maker. 

*Exposure is volume not time*
Exposure time is relative. Exposure is like filling a bucket with water. The source determines the time it takes, but like the bucket, the stencil requires a certain amount of exposure to cross-link all the sensitizer. 

How long does it take to fill up a 1 gallon bucket with water?? Without knowing how big the hose is, nobody can calculate the 'time' it takes - but I can measure it in the time it takes to make an exposure test

UV-A energy has to move all the way through the stencil to the inside of the screen. Invisible UV-A reacts with the sensitizer to cross-link the emulsion so it won't dissolve with water.

*Screen making variables*
Mesh tension - low or high
Coating trough size ratio to mesh open area
Emulsion sensitizer - Diazo or SBQ
Emulsion solids content
Emulsion viscosity - resistance to flow
Emulsion color
Emulsion age
Mesh count/color
Every emulsion has a different speed
Exact coating thickness
Coating trough _lip_
Trough Full or not, when you coat
Speed of stroke
Number of coats - Wet on Wet plus Face coats
The amount of moisture left in the coating.
Electrical power variations
The lamp type
The lamp power - Electrical watts in, then UV-A output
The age of the lamp
The UV-A energy output range
The lamp distance to stencil
The glass type in your vacuum frame
Is there a vacuum?
The color of the vacuum blanket


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## JAGGER72 (Jan 22, 2010)

RichardGreaves said:


> As a screenmaker, your first job is to harden the stencil so it doesn't dissolve with water. UV energy needs to move all the way through the stencil to the back to completely harden the stencil.
> 
> 
> 
> ...


i hope i dint sound too dence, but could you please in the most simplelest terms how to use the the 21 step transmission. please if you could step by lil step, i have one, thanks so much, maybe if you know of a vid, that would be great too


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## RichardGreaves (Nov 7, 2006)

Click on the link


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## JAGGER72 (Jan 22, 2010)

lol im not, thats the prob. i do have _Stouffer 21 Step Transmission Scale , im using diazo dual cure emulsion, (pink) 110 screen white mess, with 25 x 36 exsposer unit .the exposer unit has a timer on it aswell .with no lid. using a foam pad with a board on top of that with a weight on top of that, i dont know how to go about using the scale, do i have to waste a coulple of screens to find out my optinum exposer times, or can a burn a image during the prosses,_


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## RichardGreaves (Nov 7, 2006)

*Stouffer instructions link*



JAGGER72 said:


> lol im not, thats the prob.
> 
> i do have _Stouffer 21 Step Transmission Scale ,
> 
> ...


The emulsion, mesh count, lamp, etc. don't matter.

Tape the Stouffer scale on the stencil of every screen you expose for the rest of your life.

The link to instructions is in every quoted post in this thread.

|
V
Exposure FAQ Screen Making Products how to measure exposure


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## JAGGER72 (Jan 22, 2010)

RichardGreaves said:


> Click on the link


hey rich, i hate to admit it, but i found out what i was doing wrong, i was putting my film on the inside of the screen, lol wow, lmao. anyway when i relized what i was doing and corrected my self, and put my film on the print side, all is well, 4:30 was good for me to expose,. thanks for all ya info.


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## roninredstone (Sep 9, 2011)

how does one "harden a stencil"?


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## RichardGreaves (Nov 7, 2006)

*How does one "harden a stencil"?*



roninredstone said:


> how does one "harden a stencil"?


Emulsion is basically a poly-resin glue like Elmer's Glue except, when it dries, it will still dissolve with water.

When sensitizer is added, it reacts and joins with molecules in the resins when bombarded with UV-A energy and cross-links the emulsion components in the mesh so it *won't *dissolve with water. 

Insoluble.

Later in the process, stencil remover chemicals can break the cross-links that prevented the emulsion from dissolving and the mesh can be reclaimed.

Most lamps used in home-made sources are low in UV energy output, so exposure needed to completely cure the entire thickness of stencil can take much longer than commercial units. Speed costs money. How fast do you want to go?

Energy needed to expose is like filling a bucket with water. It takes longer with a medicine dropper, but eventually you can fill the bucket as full as a fire hose. The time is relative.


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## roninredstone (Sep 9, 2011)

Thank you. Your explanation of the exposure process had been thoroughly helpful. I have tried about 14 times now to make a screen (stencil) and have succeeded only once. The primary issue i have now is with my image (ink toner on film).

It appears to be rubbing off due to mishandling and my last exposure was complicated by light getting through the image. I though that when you said harden the stencil you meant something about hardening the ink on the film. (i understand now).


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## wBranco (Aug 1, 2012)

JAGGER72 said:


> i found out what i was doing wrong, i was putting my film on the inside of the screen, lol wow, lmao. anyway when i relized what i was doing and corrected my self, and put my film on the print side, all is well, 4:30 was good for me to expose,. thanks for all ya info.


1)does that really matter??
2)4:30?? how many Ws??
3) hey im using textile dw emulsion (used to be purple now its brown(cause of the sentitizer)) with 360w how much time should expose for?? 
my remover didn't work on the first one this is my forth try exposing and removing obviously I printed as well and nothing..here are the images of what it looks now ...can I print like this ??? I used bleach and other things to clean it. I once clean it with bleach and then did the whole process but I exposed in the back side of the screen. was that the problem..or what??
img 1)
https://mail-attachment.googleuserc...809&sads=T8Ne_1gZiGyxnjGserAt7WIgGOU&sadssc=1

img2) 
https://mail-attachment.googleuserc...343804811811&sads=GoKiq8xYzyPi8Tct943fJVha73Q

img 3)
https://mail-attachment.googleuserc...343804848685&sads=kempyOw_JXruBYP7epQ_FfWk-pE

img 4)
https://mail-attachment.googleuserc...343804888543&sads=JgxLLPgyetWioQueSonNXIx8uOc

ps. the screen was brown with my design not trasnparent but semi


thank you for your help!!


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## RichardGreaves (Nov 7, 2006)

wBranco said:


> *1)*does that really matter??
> 
> *2)*4:30?? how many Ws??
> 
> ...


1) Yes, it matters where you put the positive. It's job is to block UV energy from reacting with the sensitizer and changing the stencil from something that dissolves with water *INTO* something that won't dissolve with water -*ESPECIALLY* with water-based ink. If you don't completely cure the inside of the stencil, the raw stencil will breakdown with the combination of the water & ereaser rubbing of the blade.

2) 4:30 seconds for a diazo stencil is what I would expect from a commercial screen exposing 1K (1000 single lamp), unit. 40 watt BL lamps at least 12 minutes.

3) 360 watts? I'm guessing you are adding up multiple fluorescent lamps to come up with 360. Even commercial, 40 watt BL lamps only output* 9 watts of UV energy* at 5 inches

*Emulsion*
The two parts that make "emulsion" are poly-vinyl acetate (white glue, like Elmers), *surrounded *by poly-vinyl alcohol that the sensitizer joins with.

Under-exposed stencils means some of the stencil you want to resist water - doesn't. The PVAlcohol dissolves on some molecules revealing PVAcetate that then sticks to your mesh *LIKE GLUE*. Stencil remover won't release it. 

Bleach is a very weak method of breaking the cross-links formed by exposure to make a stencil insoluble. No cross-links because of under exposure, no mesh reclaim - bleach or commercial sodium meta periodate (SMP).

I've got about 20 posts on bleach
http://www.t-shirtforums.com/search.php?searchid=4079111


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## wBranco (Aug 1, 2012)

1) ? huuh lool can you explain it like if u were explaing it to a ten year old :$
2) ahh so if its 300w normal lamps like the ones for the office or hallway in your home. then it would be 40w=12
300/40=7.5
7.5x12=90m
90m=1hr 30m exposure time yes??
3) yes different lamps to make 360 or 300 depending if i use one lamp or not 
https://mail-attachment.googleuserc...343955414341&sads=5GlBdRH2S_9rCSgMHMfuOjOkJuk

about 10 or 12 inches 

emulsion: ohh nice i did smell the glue smell hahaha

oh so i have experienced some underexposure( i started with 16 minutes the 19 and then 32 and it turned yellow but still lost details, so im guessing with my math above it would be 1hr and 30 minutes of exposing eh? )

"The PVAlcohol dissolves on some molecules revealing PVAcetate that then sticks to your mesh LIKE GLUE. Stencil remover won't release it. " HUH??

"Bleach is a very weak method of breaking the cross-links formed by exposure to make a stencil insoluble." is there anything strong enoough??

"No cross-links because of under exposure, no mesh reclaim " but after my first exposure i printed it on a shirt and then i washed it but the emulsion didnt take out very good with the remover and i then washed it with water...soo idnt knw if its creossed linked :S
those pictures were taken yesterday i washed it today with bleach and its much cleaner then yesterday but still not white enough and unlike the cleaning videos when washed with water it doesnt remove :S [media]http://www.youtube.com/watch?v=hZJu-0a0Dl4[/media]

(i dint use pure bleach aas she did today and i did it exactly like she did) (yesterday i let the mixed bleach (water) to stay there to about 5,8,10 minutes each)

" bleach or commercial sodium meta periodate (SMP)." huh?? lol srry :s


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## RichardGreaves (Nov 7, 2006)

Your Google attachments don't work.


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## RichardGreaves (Nov 7, 2006)

wBranco said:


> oh so i have experienced some underexposure( i started with 16 minutes the 19 and then 32 and it turned yellow but still lost details, so im guessing with my math above it would be 1hr and 30 minutes of exposing eh? )


The simplest way to understand your exposure volume is to measure it rather than keep guessing.

A *manual, stepped exposure test* looking for the amount of exposure that no longer gets a *diazo color change* reaction of the stencil will tell you your maximum exposure time. 

Because of the physics Inverse Square Law, simple math won't get you an answer.

10-12 inches from glass defeats almost all the light energy of your fluorescent lamps. The industry standard is 4 inches from glass, on 4 inch centers.

Office or hallway fluorescent lamps are designed for reading, not exposing UV sensitive stencils. Look at the model or style of your lamps. If they're NOT *BL*, you only have a minuscule amount of UV energy and hardly any *penetration power* need to get to the *inside of the stencil*. If you can see the light or you feel infra-red heat from a lamp, that energy means nothing to UV sensitive stencils.



wBranco said:


> "The PVAlcohol dissolves on some molecules revealing PVAcetate that then sticks to your mesh LIKE GLUE. Stencil remover won't release it.
> 
> " HUH??


Perhaps you could identify what is confusing you rather than just writing "HUH?" As a teacher, I need to understand where the gap is between what I wrote and what you understand. 

Underexposed means the outer covering of PVAlcohol surrounding the PVAcetate (glue), dissolves on some molecules during development and glues the stencil to the mesh and now that it's glued to the mesh, stencil remover or bleach won't defeat the glue.



wBranco said:


> "Bleach is a very weak method of breaking the cross-links formed by exposure to make a stencil insoluble." is there anything strong enoough??
> 
> 
> 
> ...





wBranco said:


> (i dint use pure bleach aas she did today and i did it exactly like she did) (yesterday i let the mixed bleach (water) to stay there to about 5,8,10 minutes each)
> 
> " bleach or commercial sodium meta periodate (SMP)."
> 
> huh??


I posted a link, to a T-Shirts Forum search with more than 20 results of homework posts by me about the inferiority of bleach, compared to commercial stencil remover *sodium meta periodate* (SMP).

http://www.t-shirtforums.com/screen...ting/screen-printing/search....archid=4079111


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## wBranco (Aug 1, 2012)

u got my post??


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## RichardGreaves (Nov 7, 2006)

wBranco said:


> u got my post??


If you mean Greaves, no.


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## wBranco (Aug 1, 2012)

materials:
textile dw emulsion
lava lamp as asafe lamp
4oz speedball ink water-based
diazo water remover
120 v bulbs and 12 v bulbs office lamps
shower as washishng booth and high pressure water source
squeege 9"
16x20 screen week old 
3m copier universal acetates PP2200
canon M3X10

process: 
mixed well emulsion using safe light 
coated screen using save lamp
exposed it in the wrong side :S where the squeege goes (did that all the times except one, the last one) for 16 minutes. didnt changge colors
then i washed it in the shower not so strong as i found out it could do stronger if u just open more the water flow.
printed and it printed
washed eexactly as the directions said and it didnt do anything

problems:
now it doens print even since the second try i think its clogged. i used again the remover in my next 2 tries nothing happened so i searched and found out about bleach. it did more than the remover it didnt look brown it looked pinkish and a bit more clear just a bit...then i found the vid above and tried it as she said and it worked but still not transparent as a new screen but i can see my hand and i can stil see the image from the first time and second (1st completly transparent 2nd a bit less 3rd a bit less). So I could see it looked clogged cause of the pinkish emulsion it hasn’t fade away. And I c ant it see like the cleaning screen videos that they starting washing it and it goes off by magic mine just stays there and I have to work it but not much done. 
This time I exposed it double the time (meaning 32 minutes) with the lamps. And doubled my image to be darker and exposed it in the right place; the back of the screen. But I did noticed I made a mid coat meaning not thin but not thick either but thicker then the other ones

Questions: 
Does my screen still work even if its semi transparent with spaces 100% transparent. Water doesn’t go through the screen just in random small spaces an dthe ink doesn’t go through either even in the last try. Is it not completely clean because I don’t have the water preassure thingy??
“If the exposure time is too short, there are fewer cross-links to break and the emulsion will be very difficult to dissolve. No cross-links = hard to reclaim.

More exposure means, more, or hopefully, complete exposure/curing/hardening/cross-linking of the stencil. If you add even more exposure - you waste time, lamp life and electricity, but it won't hamper stencil removal. You my get a under cut, light scattered, choked image, but it will reclaim like a dream. It's counter intuitive - I know.”
Is this the reason I cant get my screen washed completely with just one week of doing so when a person with over a year does it so easily like a “dream”??
Do I need to buy a new screen to wait and use a water pressure on this screen or shld I just cut it and buy 1 yard of 80 mesh and staple it with normal stapler??
If I used the sun how long will I need to expose for?? Its prett standard right?? Im looking towards the sun so looking south.

Is it bad to was it in the shower even when opening the water flow to the fullest??

With my films what kind of setting shld I use?? I tried the print on the printer and didn’t dry so I tried the copy setting and it worked better; it dries over two days. But the stencil comes out with some pinholes although I have a permanent marker that I use its super big so on fine detail it does not work.
The printing settings on the computer are photopaper double sided and just black ink and the iage is only black and white. There is no option for acetate.


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## RichardGreaves (Nov 7, 2006)

*3M PP2200/100 Photocopier Transparency Film* is designed for dry-toner copiers that use 300F heat to fuse dry-toner to the film. This is why laser printers & photocopier finished sheets feel warm.

You're using this *dry-toner film* in a Canon *ink-jet printer* that uses liquid, water-based ink that's notorious for being TRANSPARENT. That's a good for full color photographs, but bad for UV opaque spot colors. 

*Canon* and HP printers use *thermal heads* that heat the ink to 500°F over and over, producing a vapor bubble in the ink reservoir (bubble jet). When the ink expands, droplets are ejected through the nozzle. This cannot be increased with RIP programming. One of the side effects of the high heat is that the cooling phase alters critical nozzle alignment.

Dry-toner films hold a static charge that temporarily hold the dry-toner on the film or paper, until the plastic toner can be melted on the film by the fuser. 

Ink-jet films require a special, ink absorbent coating on a 5 mil polyester film base. The coating loves water, which is the carrier for the ink. 

*Screen Age*
Today I used a screen that was more than 10 years old so I don't understand what you're concerned about.

*120 v bulbs and 12 v bulbs office lamps*
I can't imagine any UV energy of any power strong enough to excite diazo sensitizer.
Examine the lamps for their model type. Can you get a sun tan from those offie lamps? If not, they don't radiate much UV energy like the sun.

*Diazo Color Change*
You have some advantage because you are using a diazo sensitized emulsion that changes color as it's exposed. Faster exposing emulsions sensitized with SBQ don't change color, so the *manual stepped exposure test *doesn't help much. A Stouffer 21 Step Gray scale can be used on ANY stencil to determine if it's cured/hardened.
Exposure FAQ Screen Making Products how to measure exposure

If your stencil doesn't dissolve with water, some UV energy is hardening the bottom of the stencil like the crust on a loaf of bread.


*"washed eexactly as the directions said and it didnt do anything"*
Is this your description of the stencil removal process? If so, please refer to BOTH my explanations of why under-exposure interferes with stencil removal.

I assume that clogged mesh is proof you didn't remove the stencil.

I'm sure bleach may work for many people, but your proof it doesn't is right there in your mesh.


More stencil remover after the first try that was doomed because of your under-exposure is a waste of time as you found out.

For a time, tape a thin coin, washer or aluminium foil to an edge of your screen to serve as a comparison to the UV opacity of your positive.

If water doesn't go through the mesh, you know what's wrong.


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## wBranco (Aug 1, 2012)

so like the emulsion remover didnt work what shld i do
buy a new screen and keep trying to clean the clogged one or buy a new mesh and rip the old mesh out??
btw can i staple the mesh to the frame with a normal stapler meaning small staples ?? or does it have to be with a stapler gun??


is their any remedy in cleaning the clogged mesh??

i heard about the coin and aluminion i just dont really get it; what it does?

yeah i think it was underexposed and thats why its hard to erase or clean and the remover didnt work at all.


im going to use the sun i just need to know how long does it take.



if i overexpose does it damage my screen?? if i do overexpose what can i do to wash the emulsion off when needed??

about the printer..i found the solution


thanks for your help


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## RichardGreaves (Nov 7, 2006)

wBranco said:


> yeah i think it was underexposed and thats why its hard to erase or clean and the remover didnt work at all.
> 
> so like the emulsion remover didnt work
> 
> ...


Since you only have one screen, you should plan on buying more of a selection of screens. 

Since you're a beginner, you should study screen printing and screen making is certainly an important part of that study.

*Buy the book*
Go to:* T-Biz Network Store
and buy *"How To Print T-Shirts for Fun and Profit!"* the textile screen printer's primer since 1979. You can get it in *PDF format* that means instant delivery via the Internet.



wBranco said:


> btw can i staple the mesh to the frame with a normal stapler meaning small staples ?? or does it have to be with a stapler gun??


*MOUNTING THE MESH*
Office staples designed for paper won't hold under the tension required for screen printing mesh tension. The staple method is adequate for many small shops, but staples are messy, expensive and more difficult to work with than the stretch-and-glue method. 

Beware, staples destroy expensive mesh and decrease the life of the wood frame because of the holes they make in the wood.

*Adhesives*
Adhesives hold the mesh evenly to the frame, eliminating *uneven mesh tensions and tearing*. While there are a number of adhesives available, the ideal adhesive should have: 

high resistance to temperature and humidity changes
ability to repel ink solvents, cleaning agents and water
quick drying and setting, and high elasticity
a lack of corrosive acids.



wBranco said:


> is their any remedy in cleaning the clogged mesh??


 Brute force of high water pressure is your last resort. After that, only the knife can fix the mesh.



wBranco said:


> i heard about the coin and aluminion i just dont really get it; what it does?


You're using inferior positives that don't stop all UV energy like a raincoat made of mesh, so your screen making is out of control and UV energy leaks onto image areas that you want to dissolve with water. FAIL.

All quality control is based on comparison, and KNOWN products with 100% guaranteed UV opacity are control guides.

*Dime - Complete Opacity Test*
Next time you expose a screen, tape a dime (the thinnest USA coin) or a piece of aluminum foil to the stencil, to see how the dark areas of your positive *compare *during development. No UV energy will penetrate the dime and it should wash out like a dream. You can then compare how your image area doesn't dissolve as easily as the area covered by the dime.









If the area covered by the dime *doesn't wash out*, you've exposed the stencil to UV energy or heat energy when you dried & stored it and the stencil resists dissolving with water and going down the drain.



wBranco said:


> im going to use the sun i just need to know how long does it take.


No one can tell you correct screen exposure for your sun conditions.

Every day, every hour, every weather condition, mesh count, every emulsion & coating thickness will give you different UV exposure conditions.

*Homework reading*
http://www.t-shirtforums.com/screen-printing/t22316.html#post135805
http://www.t-shirtforums.com/screen-printing/t19817.html#post121127
http://www.t-shirtforums.com/screen-printing/t74293.html#post444342



wBranco said:


> if i overexpose does it damage my screen?? if i do overexpose what can i do to *wash the emulsion off when needed??*


_*wash the emulsion off when needed??*_
Do you mean reclaim the mesh? Stencil removal? Stencils aren't like dirt or grease that you wash off your hands before eating. You cure them with UV energy so they resist squeegee friction, water and solvents. Water-resistant stencils are even harder to reclaim.

*Overexposure?*
Stencil exposure is not like *overcooking *food *that dries out,* or UV burned skin at the beach. It's more like a sponge. 

Spill a glass of water and a sponge absorbs all of it with room for more. 

Put the same sponge in a gallon or water or *the Atlantic Ocean* and there will be a point when the sponge is saturated and just can't take anymore. You can hold it in the bucket for an hour, but you only waste your time with no further change in the amount of water it can hold.

It's like cured plastisol or concrete - you can't over cure. No real harm comes from exposing a stencil after all the sensitizer is cross-linked, you're just wasting time and electricity.*

Imagine your positive stopped all UV energy, you could expose for hours and eventually there would be no more sensitizer to cross link.

The stencil wouldn't change anymore no matter how long you exposed.

*Exposure is volume, not time*.
How long does it take to fill a 1 gallon bucket with water? A medicine dropper could take 2 hours, but the firefighters next door take only 2 seconds. All you do is waste time and UV energy once you reach the saturation point.

Do not confuse *light scatter* or *under cutting* from angled or diffused lamps with over exposure! Light coming from 2 sides will choke the size of fine lines because the light falls on the positive at an angle but that isn't over exposure.

The only way to *compensate for undercutting & light scatter* is to make lines and dots larger in the art so they survive exposure if you want a completely cured, durable stencil that reproduces the exact fine lines desired by the designer.



wBranco said:


> about the printer..i found the solution


Someday, you might enjoy sharing what you found as a solution to help others with the same problem.


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## wBranco (Aug 1, 2012)

whats the highest psi you can use to reclaim a screen??


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## wBranco (Aug 1, 2012)

staples info= got it
simplier to just buy a ready made

dime= got it
will do that in my next try



"Water-resistant stencils are even harder to reclaim." so what do you do??

if i overexpose my water based emulsion on my screen does it make it hard to wash out(reclaim) or impossible?? is it even possible to wash the overexposed emulsion out completly??


"The stencil wouldn't change anymore no matter how long you exposed." soo it doesn't damage my screen right? just to be 100% clear

"Exposure is volume, not time...." very good example...im going to use the sun  lol better than the 5 lamps


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## RichardGreaves (Nov 7, 2006)

wBranco said:


> whats the highest psi you can use to reclaim a screen??


In the early 1980's, Hydroblaster of Utah taught the world how to reclaim mesh without ant stencil remover using 3000 psi water.

High tension mesh helps because it doesn't vibrate the mesh with the pulsations of the water.

Public car wash places are very popular. Don't leave a mess.


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## wBranco (Aug 1, 2012)

my friend has 3100 psi but its complicated to move around cause it doesnt fit in my car or his

what about a so 1200 psi warm water is good??


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## RichardGreaves (Nov 7, 2006)

Will your screens fit in your car?

?If you kick a door in, does it help to have a warm boot? 
If you want to DISSOLVE a stencil, warm water helps.


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## wBranco (Aug 1, 2012)

im going to a coin carwash 

"?If you kick a door in, does it help to have a warm boot?" nope 
"If you want to DISSOLVE a stencil, warm water helps." remove is what i want 
reclaim is what i want


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## RichardGreaves (Nov 7, 2006)

wBranco said:


> im going to a coin carwash
> 
> "?If you kick a door in, does it help to have a warm boot?" nope
> "If you want to DISSOLVE a stencil, warm water helps." remove is what i want
> reclaim is what i want


Those statements are intended to explain why warm water is irrelevant if you use high pressure water. Without commercial SR, you will have problems dissolving a used stencil.


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## wBranco (Aug 1, 2012)

commercial sr? whats that?


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## RichardGreaves (Nov 7, 2006)

*What is commercial SR?*



wBranco said:


> commercial sr? whats that?


In Posts 17 & 20 I mentioned commercial stencil remover.

_"If your bleach technique works, you should keep using it. If it doesn't work, I suggest using commercial stencil remover with the active ingredient sodium meta periodate (SMP)."_

I see the post with my search for 'bleach references doesn't work anymore. Here's another one. 
T-Shirt Forums - Search Results


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## happyprint (Sep 29, 2011)

hello Mr.Graves about emultion color..why water resistant emultion different color with the solvent resistant emultion? and why waterbased resistant emultion need less time to exposed than solvent resistant emultion?? it's that becouse of the color??


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## happyprint (Sep 29, 2011)

hello Mr.Graves about emultion color..why water resistant emultion different color with the solvent resistant emultion? and why waterbased resistant emultion need less time to exposed than solvent resistant emultion?? it's that becouse of the color??


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## happyprint (Sep 29, 2011)

hello Mr.Graves about emultion color..why water resistant emultion different color with the solvent resistant emultion? and why waterbased resistant emultion need less time to exposed than solvent resistant emultion?? it's that becouse of the color??


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## RichardGreaves (Nov 7, 2006)

*Emulsion color questions*



happyprint said:


> why water resistant emultion different color with the solvent resistant emultion?
> 
> why waterbased resistant emultion need less time to exposed than solvent resistant emultion??
> 
> it's that becouse of the color??


Emulsion color can effect exposure speed by filtering UV energy, just like mesh color.

An example would be Ulano RLX & TLX both dual-cure emulsions designed for fine lines & halftones. UV energy exposure cures the stencil at diazo sensitizer speed. Internally they are the same except for the dye added for color.

*Magenta vs. Teal color*
Many people say that RLX *looks solid* with its lovely magenta color, but I always used TLX because I could register multicolor prints faster since *I could see through* the pale green/blue color - and it exposed 20% faster than RLX. I have since 1985 I've measured stencil hardness (aiming for a solid step 7), with a US$10 Stouffer T-2115, 21 step gray scale that simulates 21 exposures on every screen. Properly used you could make this 5 inch positive last a lifetime.

Many single color printers like dark colors because pinholes in the stencil are easier to see and block, but dark means less transmission of light - slower exposure.

TLX exposes faster than RLX because the reddish color (red *R*LX teal *T*LX), filters UV energy.

*Diazo*
Sensitizers are the UV sensitive "joining" agents that hold the stencil in the mesh when it's exposed. The sensitizer used in _most_ water-resistant emulsions contain diazo compound and phosphoric acid. It's the acid (like most after exposure treatments to make stencils permanent), that fights reclaiming & washup chemicals.

If you want water resistance, you want a diazo sensitizer. If you're only printing short runs you may be able to use a faster photo polymer sensitizer like SBQ.


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## happyprint (Sep 29, 2011)

thanks for reply Mr.Greaves.. so emultion water resistance and solvent resistance is same formula..the different is only dye color..and that cause speed of expose time.. so can i add dark pigment (waterbased pigment) to my emultion for lowering speed my exposed time? i expose my screen by sun.. and the UV very high in Idonesia.. many time i over exposed in only 50 second..


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## RichardGreaves (Nov 7, 2006)

happyprint said:


> so emultion water resistance and solvent resistance is same formula..
> 
> the different is only dye color..
> 
> and that cause speed of expose time.


No.

Your question was about color. I gave an EXAMPLE of a specific emulsion formula and how the dye color effects it. RLX & TLX are dual-cure textile emulsions. I wrote the only reason I know of that would lead a screen maker to choose the darker stencil. 

*Water resistance* and *solvent resistance* ARE based on the secret internal chemical formulas for *any* emulsion and *they have nothing to do with dye color*. It is very difficult to combine solvent and water resistance as they require different chemical goals.

Your latest post seems to reveal more about what your real problem -For some reason, you want to slow the exposure speed of your stencil. 

This is a problem I don't understand. 

If you've exposed too much, you shorten the exposure time.

There is no harm in over-exposure. There_ is_ harm in weak positives.

What does over-exposure mean to *you*.

Tell us about the emulsion you're using and how you measure your exposure.


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## happyprint (Sep 29, 2011)

when i over exposure it's very hard for me to wash out my picture expecialy in lines or halftone. yes that's my bad i only presume my exposure time.because i use sun for expose.. yes i know it's different every time/unpredictable.
i use diazo emultion for water resistance and it's very solid..but i think if i can slower my exposure time it's saver for me..the UV here very high i think.. in 50 seconds i will over exposure. so i can't add pigment to my emultion..oke.. i have shorten my exposure time now


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## RichardGreaves (Nov 7, 2006)

happyprint said:


> when i over exposure it's very hard for me to wash out my picture expecialy in lines or halftone.
> 
> yes that's my bad i only presume my exposure time.
> 
> ...


Your problem isn't overexposure, it's POSITIVE FAILURE.

Please re-read my Post 27 in this thread.

The purpose of the positive is to stop UV energy from hardening your image area. If your image area doesn't dissolve easily, UV energy has leaked through your positive and 'crusted' the image area. Use a thin coin or aluminium foil as a comparison test to your positive. A coin will never fail to stop ALL UV energy.

I understand your problems but, underexposing the parts of the stencil that must stay in the mesh because your positive is failing will always be frustrating.

How are you making your positives?

Here are 3 pages of Search Results for answers I've posted in this Forum for the word 'dime' to study:
T-Shirt Forums - Search Results


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## happyprint (Sep 29, 2011)

yes i think you right Mr.Greaves.. my positives realy bad.. i only use 80 gram hvs paper print with postcript laser printer and rubbed with vegetable oil.. so i have to underexposed every day..and that's why my stencil easily breakdown when i use waterbased ink for long run..


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## ryanellsworth (Jul 5, 2012)

I'm pretty new to screen printing and am trying to get exposing down as well...I have symptoms of what seems like both under and over exposure, pretty confusing. 

I am using a uv black light exposure unit I just built with 4 tubes about 6" from the glass. Using ulano qx-1 and qt-discharge I followed the recommended BL times on their site, and my first try gave me what looked like a solid step 14. WHAT?? Well I guess it makes sense, since it was hard to wash out and reclaim.

So I cut the time in half to 100 seconds for qx-1. Now it looks like I have a solid step 12, however the image washed out pretty easy and turned out pretty good. But the ink side of the screen was slimy, which I thought is caused by under exposure. 

I am doing one coat on each side as well as scraping off excess emulsion...any advice? Am I over exposing? Under? 

Also not sure if I'm even reading the steps right, since some of the steps are more see through? Does solid step mean solid not washing out or solid the same color as the rest of the emulsion?

Pic:


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## RichardGreaves (Nov 7, 2006)

*Reading the 21 Step Stouffer scale*



ryanellsworth said:


> I am using a uv black light exposure unit I just built with 4 tubes about 6" from the glass. Using ulano qx-1 and qt-discharge I followed the recommended BL times on their site, and my first try gave me what looked like a solid step 14. WHAT?? Well I guess it makes sense, since it was hard to wash out and reclaim.
> 
> So I cut the time in half to 100 seconds for qx-1. Now it looks like I have a solid step 12, however the image washed out pretty easy and turned out pretty good. But the ink side of the screen was slimy, which I thought is caused by under exposure.
> 
> ...


On the Stouffer T2115 Gray Scale, the numbers are clear and get 100% of the energy you expose it with.

On your stencil, Step 21-14 dissolved completely, but *you don't have a solid step yet*. Solid means you can't see the number. If you *can* see the number, you know the stencil surrounding it dissolved - thus it's not completely cured.

You noticed the slimy evidence of what happens when fluorescent, low UV power didn't penetrate all the way through the stencil to the inside of the screen where your stencil will get rubbed like an eraser by the blade.









Exposure FAQ Screen Making Products how to measure exposure

Dual-cure QX-1 has a suggested exposure time for BL lamps coated on 305 mesh of 203 seconds. Water resistant QT-Discharge on 156 mesh needs 420 seconds using BL lamps. You don't share with us your mesh or the exact type of lamps you used in your exposing unit.
Pre-Sensitized Dual-Cure QX-1 Direct Emulsion

Water Resistant Emulsions from Ulano 925WR QT-Discharge TZ

Consider that you're using one of the diffused, weakest, multi-lamp UV sources AND exposing stencils designed for halftones or fine lines and durability against water-based discharge inks.

If you're printing plastisol, you can get away with poorly exposed stencils, but you're asking for reclaim problems when you underexpose.


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## ryanellsworth (Jul 5, 2012)

*Re: Reading the 21 Step Stouffer scale*

OK, thanks for clearing up what is actually a solid step. It looks like I had maybe a 3 in that picture. So I should go back to the recommended time. I am using 160 mesh and 4 24" blacklight tubes, here are the exact tubes:

GE 10244 - F20T12/BL - 20 Watt - T12 Linear Fluorescent Tube - Black Light | 1000Bulbs.com

I think I may be falling victim to a little pre exposure as well. Although it's dark, a tiny bit of light comes through the side of the door in the room that the screens dry in. That may be why some parts of the stencil will wash out and some won't. For my positive I'm using transparent waterproof film, printing with black dye inks on the highest setting.

Is there a different emulsion other than qt discharge I should be using? I do water base and discharge inks.


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## RichardGreaves (Nov 7, 2006)

*Exposure Math for Stouffer Scale*



ryanellsworth said:


> OK, thanks for clearing up what is actually a solid step. It looks like I had maybe a 3 in that picture. So I should go back to the recommended time. I am using 160 mesh and 4 24" blacklight tubes, here are the exact tubes:
> 
> GE 10244 - F20T12/BL - 20 Watt - T12 Linear Fluorescent Tube - Black Light | 1000Bulbs.com
> 
> ...


BL is excellent. 20 watts is half what 40 watt lamps produce like the GE lamps at TopBulb in Indianapolis. 40 watts in - 9 UV watts energy out.
http://www.topbulb.com/find/Product_Description.asp_Q_intProductID_E_44298

Homework BLB vs. BL page
http://www.topbulb.com/find/blacklights.asp


Since you know you got a Solid Step 3 on your first exposure, you can use the instructions for the Stouffer scale or my old Exposure Math instruction on the Ulano website which is accurate for *any* direct emulsion. 4 steps to the 7th step means 4X the first exposure.


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## Rje_Printing_023 (Oct 8, 2018)

RichardGreaves said:


> As a screenmaker, your first job is to harden the stencil so it doesn't dissolve with water. UV energy needs to move all the way through the stencil to the back to completely harden the stencil.
> 
> 
> 
> ...


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## RichardGreaves (Nov 7, 2006)

Rje_Printing_023 said:


> RichardGreaves said:
> 
> 
> > As a screenmaker, your first job is to harden the stencil so it doesn't dissolve with water. UV energy needs to move all the way through the stencil to the back to completely harden the stencil.
> ...


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