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Discussion Starter · #1 ·
Hi,

So I have a Ranar 20x24 Unit, with 4 bulbs with high output unfiltered black light fluorescent bulbs (20 watts each) so that's 80 Watts. I was using ChromaBlue Pure Photopolymer Emulsion and burning my screens for about 30 seconds and it seemed to be doing a good job. (I've read so many different times)

I then ran out and bought the Ryonet HiFi Pink Photopolymer Emulsion, I burned it for the same 25-30 seconds and some come out ok and some blow out. My question is does anyone know whats a good time to exposure using the above unit with the Ryonet Hifi Photo Emulsion?

Thank you.
Joe~
 

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Depending on your stencil thickness, humidity, that Ryonet Hi-Fi is very finicky and like to be less then 40%. 45-90sec. I did on a 6 bulb black light and was 45-60 with 35% humidity
 

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Discussion Starter · #3 ·
So when I coat my screens I do 1-1 then I do another 1-1 but I just take the extra emulsion off on the second pass, is that how you guys do it? When I just do 1-1, it seems like a lot of emulsion on the screen.....
 

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If you are printing white on black garments with a low mesh count (125 or below), then yes, you DO want that extra emulsion as that is what makes your stencil. The stencil thickness is one of the most important, and overlooked aspects of screen printing light colors on dark garments.

Just make sure the last pass with the coater is on the squeegee-side, and then let the screen dry level with the print-side facing down. Due to the thickness of the stencil, you will need to allow a longer drying time before exposure - I would recommend letting them dry overnight.
 

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I just bought a used Ryonet 20x24 8 tube unit a few weeks ago. Seller gave me a fresh gallon of Texsource Procoat Pure Photo-Polymer Emulsion which is what he used. Just dialed in my exposure time at 15 seconds for halftones on 280 yellow mesh with 2-1 coating. Amazing!!! Just getting back after 5 years. My old national exposure vacuum unit was 3.2 minutes and I was happy with that. 15 seconds is crazy fast .
 

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Discussion Starter · #7 ·
So last night I went ahead and did about 10 screens with the 1-1 and just left it thicker then I normally would and today I burned one for 40 seconds and it came out ...ok, workable.

Think I should go for 30-35 or more like 50-60....

Thanks for all your comments BTW.
 

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So last night I went ahead and did about 10 screens with the 1-1 and just left it thicker then I normally would and today I burned one for 40 seconds and it came out ...ok, workable.

Think I should go for 30-35 or more like 50-60....

Thanks for all your comments BTW.
"workable..." Meaning what?

If it was still a bit slimy on the back, then it is underexposed, so expose it longer. If the image didn't want to wash out, then it is overexposed (and/or your film isn't dark enough).

If you are printing Plastisol, you may want a thick coat of emulsion, as that is the common wisdom (though some disagree and say the thickness of the mesh should control ink deposit, not emulsion).

In anycase, if printing waterbase, forget about thick emulsion. Waterbase does not sit on top the fabric like Plastisol, rather it penetrates into the fabric.
 

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If you are printing white on black garments with a low mesh count (125 or below), then yes, you DO want that extra emulsion as that is what makes your stencil. The stencil thickness is one of the most important, and overlooked aspects of screen printing light colors on dark garments.
This is true for halftones as well. A generous layer of emulsion separates the stencil opening from the mesh and results in a considerable reduction in moire which allows one to burn finer screens on coarser mesh.
 

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Quick question please since were talking the same topic :0)

I burned some screens and when washing them out -- the edge appear kinda fuzzy so to speak. I seems as tho it should wash out more but wont. That doesn't make it sound right-- it all washed out well, looking closely I see small little like cob webby arts left behind-- the first 10 screens I burnt I had no issues, The emulsion is store accordingly :0)

Markus
 

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A fuzzy edge could be the result of poor contact of the positive to the mesh. Make sure you use enough weight and distribute it evenly to keep the positive perfectly flat against the emulsion. Also be sure you are printing on the right side of your film/ vellum. The print should be on the side that contacts the emulsion.
 

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I use a full bucket of sheetrock mud lol-- its like 65 lbs, card board, then foam then a board then weight-- I may have lightened my stroke on the emulsion-- im going to try them at a car wash today and see if it will wash all out. Will it be to late to try and wash again after original washing? Or just clean em up and go again lol

Markus
 

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You should reclaim the screen and start over. Too much weight can be a problem too because it can cause the glass to warp a bit and that can result in bad contact. And if the weight is uneven it can allow one side of the positive to lift away. Try using just enough weight evenly distributed to keep the positive flat. It shouldn't take a whole lot.

Also be sure your screen is degreased and roughened up a bit. I like to scrub the mesh on both sides with a green scrubby pad and Bar Keepers Friend® After that the water should form a smooth sheet on the mesh when you rinse it.
 

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yuppers on the degreasing-- got the sgreen stuff -- has little microbes in it lol. This image was a bit larger than the ones I had been doing and it does seem to be all onone end-- off to clean em up today-- thanks for giving all the help
 

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follow up to my last post-- I rewashed and re emulsion

I think I need more water pressure although the first ten screens had no issues, it is colder now here in NY and the temp inside reflects that some. My first screens were @ 3min spot on and worked great and washed out sweet. I do not think I am pushing the scoop coater as hard -- I ripped a screen and gun shy now lol So secodn time around I exposed the first screens at 3 mins-- so this time first screen went for 3:15. It seemed to wash out the same so i increased to 3:30 on the second screen, same thing. the last screen I did for 3:45. This seemed worse yet as it took forever to loosen up and wash out. I thought this looked "slimy" so that's why I increased time. Screens were cleaned and degreased prior to emulsion

thank you
Markus
 

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follow up to my last post-- I rewashed and re emulsion

I think I need more water pressure although the first ten screens had no issues, it is colder now here in NY and the temp inside reflects that some. My first screens were @ 3min spot on and worked great and washed out sweet. I do not think I am pushing the scoop coater as hard -- I ripped a screen and gun shy now lol So secodn time around I exposed the first screens at 3 mins-- so this time first screen went for 3:15. It seemed to wash out the same so i increased to 3:30 on the second screen, same thing. the last screen I did for 3:45. This seemed worse yet as it took forever to loosen up and wash out. I thought this looked "slimy" so that's why I increased time. Screens were cleaned and degreased prior to emulsion

thank you
Markus
Don't guess, test. See the link in my sig for info on testing exposure time.

Make sure no rough edges/nicks on the coater.

First step in washing out an image is to develop the image. You do that by running water over it for 30 seconds, or a minute, or whatever, until the image area has soaked up water and become soft. In larger areas you will see it start to wash out. Once you get to that point, then spray out the image.

If you get both slime and hard to wash out images: 1) Your emulsion is too thick; 2) Your films are not dark enough.
 

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Cold temps definitely effect how well screens burn.
I used to print out of a garage studio and would have these same issues when burning screens at this time of year. And when I would get a usable one, it would take forever to rinse off the slimy scum and keep it from drying into an invisible film on the screens that would make them unusable.
Some things to keep in mind that may help you-

•Don't forget that different mesh counts usually have different burn times. A yellow mesh 156 will take much longer than a white mesh 110.
•Emulsion works best at room temp, if possible, try to keep it and your coating out of the cold temperatures.

Also, what kind of film positives are you using? A nice, opaque film, works wonders during the longer exposure times for yellow mesh screens.
 

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Cold temps definitely effect how well screens burn.
I used to print out of a garage studio and would have these same issues when burning screens at this time of year. And when I would get a usable one, it would take forever to rinse off the slimy scum and keep it from drying into an invisible film on the screens that would make them unusable.
Some things to keep in mind that may help you-

•Don't forget that different mesh counts usually have different burn times. A yellow mesh 156 will take much longer than a white mesh 110.
•Emulsion works best at room temp, if possible, try to keep it and your coating out of the cold temperatures.

Also, what kind of film positives are you using? A nice, opaque film, works wonders during the longer exposure times for yellow mesh screens.
Temps are only affect exposure with unfiltered black lights or other fluorescent bulbs. Prewarm the bulbs for several minutes then expose the screen.

The difference in mesh size and times is affected when the coatings are thicker. I use LED 128 mesh 15 sec 166-205mesh 10 sec 272-380mesh 8 sec. when I used black lights and photopolymer emulsion it was less then 10 sec between lowest to highest mesh. Big time differences are when using diazo emulsion.
 

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Thanks for all the Info from everyone.

The images were printed on clear plastic from ryonet. They were printed with an Epson artistian 1430 set to best photo, and black/white. All blacks are 100/100/100. The light is a two bulb beginner unit from r yonet, black light ..all of the other screens went great at 3 mins..jist think it emulsion was too thick
 

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I ended up rewashing them and they came much cleaner--- I did some more screens tonite and did a 2 coat deal-- 1 to coat -- 1 to skim off :0)

Re looking at these, they just washed out like a booger lol--

Using a real gold from ryonet should I need a white underbase? (I did tho) -- must everything have a white underbase on black shirts or could I have gotten away with 2 pass on gold if needed-- I wanted to to look goldy not dulled down.

Anyhow heres a few pics of the white screen on 110, zooming in close you can actually see the screen holes lol

thanks for everyones willingness to help out and answer some questions for me.

Markus
 

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