Can't get ink through thin lines on the screen onto paper…

[Pseudo-Manitou]

Using 23x31-inch 305 mesh screen; Jacquard Water Based Ink; Ulano TZ emulsion (with exposure time of only 85-sec.); 80-lb cover-stock (French/speckletone); and a brand-new squeegee.
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I knew the design would be tricky (http://pseudo-manitou.deviantart.com...ight-353621898), but those thin lines -- I can't get ink through them onto the paper. First print showed something faint, after that, nothing. The lines are 1-point thick, I'm pressing down HARD (I weigh 200-pounds) and getting no where, and even the 3-point thick lines are barely showing. I've thinned the inks time and again with water almost to the point of making it into soup, still no good. The large portions print fine (not sure how I'm not blowing out the screen, actually). -- Where am I going wrong? My only guess is the TZ is not washing away from the thin lines enough after I expose the screen, and may be clogging it.

[Andymac]

yeah. they are probably not washed out, and now locked in.
TZ is not a very good emulsion for fine detail.
Was your positive good and dense? if the lines are light, and you are not blasting and checking with a backlight, you will have trouble printing detail

You might try a lesser mesh 230-255-28, will give you more open area. A good dual cure emulsion rated for fine detail will give you a sharp stencil.

[squeegeethree]

Yes sounds like your screen is not shot properly, but also are you wetting your screen down with water before beginning to print.
One point is also possible with a 230 although it might not be quite as sharp but it would be easier to print.

[Cranky]

I am doing pretty much the same kind of work, I am using the thinnest rapidographs and printing with 305 and 355 using Jacquard. The humidity here in Minneapolis has been crazy low and that is generally my number one problem printing detail. I have gotten a humidifier and add a bit of retarder (golden seems to work best) and water to my ink and that usually does it. I agree with the others TZ is no good for this kind of work I've been using LX-660 by ulano which works great, as well as Murakami Photocure. The good thing is spring is almost here and with it some humid air.

[Andymac]

yknow, for printing halftones and stochastic, i like to hit the screen front and back with some judicial pressure washing - cleans out that last 5-10% of stencil.

But you have to make sure your image is opaque, and your burning setup is compressing the film between glass and mesh compleltely.

I'm not going to get into coating technique and how that can affect crispy sharp printing...but a dual cure is going to give you the best chance at superfine detail and water resistance.

[Pseudo-Manitou]

Andymac: I'll be looking into a less fine mesh screen to avoid future problems. I do coat both sides of the screen, but with the TZ, exposure times may be something trickier than I remember. If what I am doing should be working for the detail, then I'm guessing my exposure time is still too long (my film is too thin?). I'm still curious if anyone knows what is the lowest exposure time needed to set that emulsion well. Thanks.

[Pseudo-Manitou]

squeegeethree: wetting the screen is something I have never tried before; no one taught me about that. So… I wouldn't know what to do, but there are people who will show me in person. I will ask. Thanks for the suggestion.

[Pseudo-Manitou]

Cranky: Never heard of Murakami (but I'm new at this anyway). I'll most likely experiment with the LX-660 first, thanks! (And yeah, this air is making everything from cooking, printing, painting, breathing, EVERYTHING more difficult. Sucks that Minneapolis is such a great place or I'd find a better climate to live in.)

[jonkeefe]

squeegeethree: wetting the screen is something I have never tried before; no one taught me about that. So… I wouldn't know what to do, but there are people who will show me in person. I will ask. Thanks for the suggestion.

Good discussion about pre-wetting in this thread: TW Graphics Screen Clogging.

My basement hovers around 30% humidity in the winter, and we can print fine enough detail to do business cards with 12pt serif fonts.

+1 for checking your washout -- we used to have thin lines lock up on us all the time, and it was from runny emulsion residue clogging the open areas. After you blow out the design from the back of the screen, do a gentle wash on the squeegee side until it stops forming soapy bubbles. Pay special attention to the top area of the screen, above your design -- this is where semi-cured emulsion is gonna run down from.

[Andymac]

wash from the front - this is the side with unexposed emulsion (the back side gets the full blast of light, right from the start of exposure, it is always hard)

YES on washing all the surface, not just the image area....the soft unexposed emulsion is the main source of scumming in the screen (clogged lines and open areas)

Check for a good exposure:

1 - All the detail of the positive is there

2 - after washout, when still wet the top surface of the stencil is 'hard', not sticky. rub your hand over it, or lay some paper on. If any emulsion residue is on your hand, or comes off the paper, or the surface is sticky you either didn't expose long enough (creep your time up) or you didn't wash long enough.

You find the balance point between image sharpness/reproduction of the positive, and a hard stencil.

Most people underexpose. this can cause premature breakdowns, or pinholes, or give you serious trouble when reclaiming screens.