# I think I under exposed ??



## azoton (May 9, 2007)

Well I think my first attempt to expose a screen was succesful for the most part.... just not printable 

Anyway, I know it's not the best light source but I used one of those halogen 500W set ups, exposing for 12.5 minutes on 110 mesh - I used ProChem DXP Pink dual cure diazo emulsion. I'm making a table top exposure unit but wanted to see if I could have any luck with the halogen light.

You can see I have some good crisp lines in the bottom portions of the image however the top parts of the image are kinda raggity.


















Am I right to assess that it was under exposed? I blew out the image with my pressure washer at it's lowest setting (you can easily put you hand in it) and it took a little while for it to start clearing out.

Is it common with this type of emulsion to it to get tacky when wet?

With a properly exposed screen just how durable is exposed emulsion? should I have to worry about too aggressively trying to clean out my image?

Thanks in advance.... I really did try to search for my answers but not much luck.


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## Powakai (Aug 21, 2007)

It just takes practice. You have too feel what you are doing when you wash out an image. Since emulsion is hygroscopic the wetter it gets the softer it gets. Plus if you are not using a dehumidifier in your screen room... etc.etc. Save your money and get a REAL light source and a poly-cop. Your problems will go away. I bought a Violux 5000 and a poly-cop used 15 years ago for 2000 dollars. They still work exceptionally well. New you are looking at 15 grand. I use SaatiChem PV textile emulsion. My screens shoot in 15-20 seconds and I achieve 5% halftones consistantly. I may have to reshoot a screen about 1 out of a hundred due to extreme humidity and complexity on the wrong day.


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## azoton (May 9, 2007)

Thanks for the reply and, yes, better equipment is down the road.

Right now just trying to interpret the results of my first attempt. I coated several more screens yesterday and am going to give it another go today.

Thanks.


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## zepher (Aug 22, 2007)

When properly exposed screens are very durable. Do you have an exposure calculator? You can find them at your screen printing supplier. Since you are using that kind of set-up, you are really going to have to do many tests to find out what's right. Down the road, I would recommend a UV exposure unit with a vacuum hold down on it. Have you tried using a garden hose to wash the image out?


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## RichardGreaves (Nov 7, 2006)

You have to learn how to make an exposure test so you don't under or over expose your stencil. You have evidence in your hands with the sticky emulsion. All emulsions are like poly-resin glues and will be sticky when wet. If you crosslink them with a sensitizer, they resist water.

Stencils are easy. If it washes out, or peels off the mesh, it wasn't exposed to enough UV-A light. Unexposed stencil should wash out easily.

If the image is hard to wash out, it was exposed to heat or UV energy and has started to cross link.

Test to see if your positive is blocking UV light. It some UV light leaks through the the positive, it can prevent the stencil from washing out in the image area. 

The next time you expose, attach a coin to the stencil which will not let any light pass.

You are using a diazo sensitizer which changes the stencil color as the UV energy activates it. SBQ stencils are MUCH faster but there is no color change, so I suggest you keep to the diazo.

All exposure questions are answered with a stepped exposure test which is essential to any screen maker.

You do a series of 'stepped' exposures on the same screen, then JUDGE the proper amount of exposure.

Exposure slide show and 2 minute video
Support Menu of Screen Making Products

Notice they also have 2 general videos on capillary film and direct emulsion under the 'general' tab. Watch those movies to learn how to reclaim a stencil once you are done with it.


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## azoton (May 9, 2007)

Thanks for thoughtful post and the link. Very good information and exactly what I'm looking for 

I gave it another go and am VERY happy with how the screen washed out and my very first t-shirt! I'm gonna chalk it up to beginners luck for now.

Thanks!


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## jundogg (Jul 20, 2007)

that's great! nice artwork too. 

can you share what you did to resolve this issue?

that's good for a start. please let us know also how you did a great print! 

what kind of ink you used and how you've printed it onto the shirt - what press you used? did you get that on one squeegee pass? how high is your off-contact (if you had any) 

thanks ang congrats!!!


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## Fluid (Jun 20, 2005)

Good Deal. Looks like you might need a little more pressure or a better flood stroke. You black looks a little thin in some areas.

Definently let us know what you did differently to get a good burn


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## azoton (May 9, 2007)

> Good Deal. Looks like you might need a little more pressure or a better flood stroke. You black looks a little thin in some areas.


I think I needed a better flood stroke.... still not sure how much, if any, pressure to put on the flood stroke. Is the idea to "float" the ink evenly over the image on the screen or to actually embed the ink lightly and evenly into the screen before the print stroke?



> can you share what you did to resolve this issue?
> 
> what kind of ink you used and how you've printed it onto the shirt - what press you used? did you get that on one squeegee pass? how high is your off-contact (if you had any)


Thanks. Someone had responded that I need to "feel" my way through cleaning out my screen after exposure and so that's what I did. Tried to get a feel for what the emulsion was and was not doing whiling washing it out. Made a big difference. I got both sides of the screen wet and let it sit more or less for about 45 secs or so and then I started attempting to wash out the image but not too aggressively... as soon as the emulsion started to look like it wanted to "fall" out of the image I just diligently helped it along but mindful not to be too forceful and let it do it's thing. Tackling like that worked great for me.

And to try and answer your other questions:

* My off contact was just slightly less than 1/8th inch
* All purpose plastisol from International Coatings
* It was a one stroke pass (I experimented with multiple strokes on another t-shirt but wasn't totally happy with the results)
* I've got a cheapy, yet functional (for me), press from silkscreensupplies.com

Thanks for the ecouragement!!


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## jundogg (Jul 20, 2007)

thanks for the info. glad about your good results. just keep practicing and finding out the areas of improvement. good luck!  

keep posting your updates because im learning from you as well.


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## RideForLifeVegas (Aug 31, 2010)

I am still learning also....I just washed out part of my image ...a small portion,,,the rest looks good. My image was hard to wash out and i guess I also under exposed it. 

The all of it finally washed out it seems except I blew out one portion on a corner.

Right now as we speak I have the washed out screen setting in the Vegas Sun. I will take pics in a bit.

If I am correct ....the blown out small portion can be saved with some packing tape to correct the blown out image ...applying the tape the the shirt side of the screen?

???????????????


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## RideForLifeVegas (Aug 31, 2010)

RideForLifeVegas said:


> I am still learning also....I just washed out part of my image ...a small portion,,,the rest looks good. My image was hard to wash out and i guess I also under exposed it.
> 
> The all of it finally washed out it seems except I blew out one portion on a corner.
> 
> ...


 Here are my burned screen images,...I am using liquid emulsion dual cure......2 coats on shirt side....one coat on ink side

And yes a YUDU screen


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## RideForLifeVegas (Aug 31, 2010)

it actually washed out better than the image proves.
in the pics it seems there is still pink in the lines but there are not now


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## RichardGreaves (Nov 7, 2006)

*If your image area doesn't dissolve - Positive Failure*

Take a few moments to review Post#5.

If you have areas of your stencil that don't dissolve, you know your exposure is working.

Compare how the image area of your positive compares to a coin.


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## JeridHill (Feb 8, 2006)

I agree, if your image is blowing out, it is most likely under exposed. Also, you don't want to use high pressure to wash out your images. Use a garden hose with regular pressure.

Richard....side note....I'm gearing up my video camera.


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