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Emulsion doesn't have crisp edges

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Old 1 Week Ago May 23, 2020 12:26:27 PM -   #1 (permalink)
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Default Emulsion doesn't have crisp edges

Hello,


so recently I have run into a problem with washing out my screen. Overall I feel like I can't retain much detail and the emulsion that is supposed to wash out doesn't occur smoothly.



I will link an image for the most prominent problem I'm facing; when I was the image out, the exposed area is fine from what I see -- not wrinkling or washing out or bubbling or anything -- but the edge of the exposed emulsion and unexposed emulsion doesn't come off clean. Tthe emulsion that washes out doesn't come off in a fluid way but rather sticks to the edges of the stencil (the exposed hardened emulsion) so when I spray the screen it's like a flap. I will link a picture to better see the stencil. You should see the design in the pink emulsion but then at the edges a more transparent pink emulsion that sticks/holds onto the pink emulsion.


another question I had: how should I wash out my emulsion? I spray it both sides with a jet function on my hose until I start to see the image outline, then I spray the garment side. However sometimes I can't retain the finer detail. Am i spraying too hard? but I feel i wont be able to get the stencil out if i just do a light spray. And I've seen others use a nice, more powerful, spray and be fine but maybe that's not the only way to do it?


I'm lost to what exactly it could be. transparency film not being opaque enough? under exposure? the way i wash out? any help would be very much appreciated! Thank you!!


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https://imgur.com/a/0K3gmfT
 
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Old 1 Week Ago May 23, 2020 1:27:54 PM -   #2 (permalink)
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Default Re: Emulsion doesn't have crisp edges

Either overexposed, or the light is leaking at the edges.
Use an exposure calculator (just google it), and make sure the film is nice and flat on the screen without any gap.
 
Old 1 Week Ago May 23, 2020 1:43:08 PM -   #3 (permalink)
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Default Re: Emulsion doesn't have crisp edges

Just had a similar issue. Think I got the emulsion on too thick and didn't let it dry quite long enough.



I just used a sponge and ran in over both sides of the screen lightly while washing it out. Did not damage the image anywhere. Did the job.
 
 
Old 1 Week Ago May 23, 2020 3:12:27 PM -   #4 (permalink)
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Default Re: Emulsion doesn't have crisp edges

overexposed? wow I would think the opposite! why exactly is the overexposure causing this? i actually did use an exposure calculator. I think i honed in my time but i may do it again.
 
Old 1 Week Ago May 23, 2020 3:14:05 PM -   #5 (permalink)
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Default Re: Emulsion doesn't have crisp edges

Quote:
Originally Posted by dwhite53
Just had a similar issue. Think I got the emulsion on too thick and didn't let it dry quite long enough.



I just used a sponge and ran in over both sides of the screen lightly while washing it out. Did not damage the image anywhere. Did the job.

my emulsion has actually been quite on the thinner side -- i only coat once and i dont go too thick.



i will definitely try the sponge thing because i feel like the power washer is too much pressure
 
Old 1 Week Ago May 24, 2020 6:18:11 AM -   #6 (permalink)
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Default Re: Emulsion doesn't have crisp edges

Quote:
Originally Posted by Theantwon
why exactly is the overexposure causing this?
The emulsion is translucent so the light does creep in around the edges.

The effect is similar to when the film is not pressed tight against the screen, again allowing light to creep in.
 
Old 1 Week Ago May 24, 2020 6:57:31 AM -   #7 (permalink)
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Default Re: Emulsion doesn't have crisp edges

What type of exposure do you use?
If you are using a halogen or over head light then you need some upward pressure, such as a foam pad, under the mesh. If you are using a exposure without a vacuum blanket then use some downward pressure from a small piece of board cut to size.
This will give a good tight contact between the glass sheet and the emulsion, which should stop light undercutting.


Is your emulsion fully dry all the way through?


Most people under expose screens, which makes them hard to wash out. A properly exposed screen should take no more than a bucket of water in total to wash out. An underexposed screen takes longer.


Use a spray attachment on a hose pipe at mains water pressure for most of the wash out.
Spray each side for a few seconds and LEAVE for a minute or so. This will both stop the emulsion exposing further and make the image easier to rinse.


Rinse with the hose pipe for a few seconds - the image should come out very easily. If you have any fine detail then a few seconds with a pressure washer will finish the job - pulse the trigger in short bursts at the fine detail.
 
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Old 1 Week Ago May 24, 2020 3:22:19 PM -   #8 (permalink)
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Default Re: Emulsion doesn't have crisp edges

Quote:
Originally Posted by PatWibble
What type of exposure do you use?
If you are using a halogen or over head light then you need some upward pressure, such as a foam pad, under the mesh. If you are using a exposure without a vacuum blanket then use some downward pressure from a small piece of board cut to size.
This will give a good tight contact between the glass sheet and the emulsion, which should stop light undercutting.


Is your emulsion fully dry all the way through?


Most people under expose screens, which makes them hard to wash out. A properly exposed screen should take no more than a bucket of water in total to wash out. An underexposed screen takes longer.


Use a spray attachment on a hose pipe at mains water pressure for most of the wash out.
Spray each side for a few seconds and LEAVE for a minute or so. This will both stop the emulsion exposing further and make the image easier to rinse.


Rinse with the hose pipe for a few seconds - the image should come out very easily. If you have any fine detail then a few seconds with a pressure washer will finish the job - pulse the trigger in short bursts at the fine detail.

I am using an overhead UV bulb. Probably will get some Styrofoam or maybe cardboard and just hold the mesh a bit against the glass.



I let my screen dry for 24 hours. I don't put a fan on it, I just let it air dry for about 24 hours.


Now how exactly can I tell it's underexposed or overexposed? I did do an exposure test and I think i honed in the right time but I guess I didn't? Also someone else said that it seems my screen is overexposed so I'm a little confused to which one it could be? I'm most likely going to do another exposure test because with what youre saying it does seem like mines underexposed -- i would actually think an underexposed screen would take less time to wash out but funny how things work!


This also may sound self explanatory, but: if i use a different printer with different ink opaqueness and what not, will that cause different exposure times? I'm not sure if my printing ink is opaque enough and I got an exposure test printed out at staples which came out very different (obviously). So should I just stick to either my printer or staples? I guess the question I have is if the ink isn't as opaque BUT still is opaque enough to block it out, will i get different exposure times?



I will also definitely try this washing out method! It also seems that if all goes well i shouldn't be washing away my design if with the hose and shouldn't be taking as long. Also how exactly does the water stop from the emulsion further exposing?


Thank you for the info and reply!!
 
Old 1 Week Ago May 24, 2020 6:33:38 PM -   #9 (permalink)
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Default Re: Emulsion doesn't have crisp edges

Quote:
Originally Posted by Theantwon
This also may sound self explanatory, but: if i use a different printer with different ink opaqueness and what not, will that cause different exposure times?
It will! Even different brand of ink may affect it.
You can actually expose the screen using any color ink, but the times will be different. I know it sounds crazy, but it does work.
Also the best transparency film is the Mylar-based one.
The acetate-based one does not allow the same amount of UV light to go through, so again exposure time will be different.
If you use the same materials all the time and you do the exposure calculator test correctly, you will be able to see how your screen is transitioning from the underexposed to the overexposed state, and where is the sweet-spot.
 
Old 1 Week Ago May 25, 2020 2:50:09 AM -   #10 (permalink)
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Default Re: Emulsion doesn't have crisp edges

Quote:
Originally Posted by Theantwon


I let my screen dry for 24 hours. I don't put a fan on it, I just let it air dry for about 24 hours.





This also may sound self explanatory, but: if i use a different printer with different ink opaqueness and what not, will that cause different exposure times? I'm not sure if my printing ink is opaque enough and I got an exposure test printed out at staples which came out very different (obviously). So should I just stick to either my printer or staples? I guess the question I have is if the ink isn't as opaque BUT still is opaque enough to block it out, will i get different exposure times?


High humidity can be a problem regarding screen drying time. That would depend on your local climate.


Films from staples might be your problem. If they are printing onto OHP slides then they may not be holding a dense enough coating of ink. You might need to double up two films. Do you not have access to an inkjet printer (in good working order)? If you have, buy a pack of good quality film and try making your own.

Your image doesn't need to be totaly opaque, as long as enough ink is printed to block the UV. Good ink contains UV filters to stop photos and documents fading. This is what blocks the UV from your emulsion.


Different inks and media make a difference to exposure, mainly because some aren't as suitable for the job as others. If all you have to do is buy a pack of suitable film to get a good result, what point is there in using less suitable media?
 
Old 1 Week Ago May 25, 2020 7:52:45 AM -   #11 (permalink)
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Default Re: Emulsion doesn't have crisp edges

I think the problem may also be in combining too many sub-optimal components. Here is a quick list:


1. Using window glass instead of quartz glass. Window glass blocks UV light, and the thicker the glass the worse the problem gets.
2. Using UV blocking transparencies.
3. Using low UV intensity light source.
4. Using low density inkjet ink.

Combine the 4 and you will have difficulties. Eliminate 2 and 4, and you could get away with the other two.
 
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Old 1 Week Ago May 25, 2020 11:56:20 AM -   #12 (permalink)
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Default Re: Emulsion doesn't have crisp edges

Quote:
Originally Posted by PatWibble
Films from staples might be your problem. If they are printing onto OHP slides then they may not be holding a dense enough coating of ink. You might need to double up two films. Do you not have access to an inkjet printer (in good working order)? If you have, buy a pack of good quality film and try making your own.

I actually do use an inkjet printer! My printer doesn't print black well; whenever I print black when it comes to photo printing it comes out green. I've messed with the settings and no luck. With this i actually did start lining up and doubling up films. It was working fine but my problem is when I get into fine/high detail they don't line up perfectly and I'm not sure if one sheet will cut it. My last exposure I did use one sheet and the design showed as i was washing it out but then I ran into the problems of it not cleanly coming off. That's why I wasn't sure if the single film sheet was causing underexposure or not causing a problem at all.


The film I was using had a glossy side and a matte/grainy side (the side you print on) so if I'm correct not OHP film? But I'm going to look into maybe better film. Again the image does come out and is seen (when I doubled up -- in the beginning I actually TRIPLED up because I would think if no regular light can't get through then UV should be good too) but the sides and edges of the designs is what is causing headaches.
 
Old 1 Week Ago May 25, 2020 12:01:56 PM -   #13 (permalink)
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Default Re: Emulsion doesn't have crisp edges

Quote:
Originally Posted by TABOB
I think the problem may also be in combining too many sub-optimal components. Here is a quick list:


1. Using window glass instead of quartz glass. Window glass blocks UV light, and the thicker the glass the worse the problem gets.
2. Using UV blocking transparencies.
3. Using low UV intensity light source.
4. Using low density inkjet ink.

Combine the 4 and you will have difficulties. Eliminate 2 and 4, and you could get away with the other two.

Crazy how so many little issues can create a big problem.



So it seems like, if all these problems are occurring, that the image that is supposed to wash out is actually getting more exposed than it should? hence the difficult wash out?
 
Old 1 Week Ago May 25, 2020 12:53:58 PM -   #14 (permalink)
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Default Re: Emulsion doesn't have crisp edges

Quote:
Originally Posted by Theantwon
So it seems like, if all these problems are occurring, that the image that is supposed to wash out is actually getting more exposed than it should? hence the difficult wash out?
What happens if you mix all these together is that the exposure time will be too high, so you are more likely to start with underexposed screens.
When you increase the exposure time to 15 minutes or something like that, then the screen is actually cured, but your image area is also partially cured and the top layer of the edges is also fully cured. It seems to me that this is the problem you are having.



I personally use a laser printer and toner is very opaque. Then I place the printed side against the screen, so the light cannot get diffused through the film... There is no gap at all.
 
Old 1 Week Ago May 25, 2020 6:53:26 PM -   #15 (permalink)
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Default Re: Emulsion doesn't have crisp edges

that makes sense. Right now the exposure time I have is roughly 25 mins for a yellow mesh 230...I'm only using the ryonet DIY UV bulb about 1.5-2 feet high above the screen. I'm going to try to get a good opaque stencil then do another exposure test.
 






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