# Problem Washing Out Small Halftone Dots



## earwicker7 (Oct 27, 2014)

I have a design which has been giving me some trouble on washout... everything comes out pretty easy except the really small dots.

The design has some 9% Pantone Black halftones, and it's been pretty hard to get those to wash out. The next step up is a 13% area, and it comes out pretty easily.

Is it possible that the dots are too small for a 230 mesh, even if it's printed at the correct LPI, which in this case is 45? Would going to a 305 give me better results?


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## mushroomtoxic (Sep 5, 2013)

I would first check, your film density and make sure there dark enough to properly transfer the 9% gradient. To me if your not captureing that range you could also be over exposing just slightly. 9% to 13% isn't that far away from each other. also to consider your type of light source your using, and emulsion. I use murakami aquasol HV with diazo, and SP7500 dual cure. both are great for plastisol and wb inks. check out there site, they have a great read on the science www.murakamiscreen.com

my 2 cents


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## sben763 (May 17, 2009)

I will take a wild guess and say you are using a unfiltered black light unit. If this is the case you are getting undercutting. Depending on your emulsion you can back off your exposure time slightly. On a photopolymer 15-25 sec. On a diazo emulsion 30-60 sec. I'll bet if you had densitometer your 13% will be much smaller then they are suppose to.


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## earwicker7 (Oct 27, 2014)

I have an Epson 1430 with Black Max, so the film density definitely isn't an issue. 

The exposure unit is an unfiltered UV unit, but it's a fairly good one. I will try backing off the exposure times a bit.


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## sben763 (May 17, 2009)

earwicker7 said:


> I have an Epson 1430 with Black Max, so the film density definitely isn't an issue.
> 
> The exposure unit is an unfiltered UV unit, but it's a fairly good one. I will try backing off the exposure times a bit.


There are no quality differences with the unfiltered black lights as long as the right bulbs and clear glass are used. Differences in the units are more or less bulbs. Under cutting is inherent in these units. 

Are you using accurip and have all the droplet density or printing from a graphics program. Just cause your using blackmaxx if it's not laying enough ink there can be issue on the lower tones. There have been others here before and that ended up being the issue. When I used a unfiltered black light unit I had to under expose anything under 10% and anything under 5 was lost.


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## earwicker7 (Oct 27, 2014)

sben763 said:


> There are no quality differences with the unfiltered black lights as long as the right bulbs and clear glass are used. Differences in the units are more or less bulbs. Under cutting is inherent in these units.
> 
> Are you using accurip and have all the droplet density or printing from a graphics program. Just cause your using blackmaxx if it's not laying enough ink there can be issue on the lower tones. There have been others here before and that ended up being the issue. When I used a unfiltered black light unit I had to under expose anything under 10% and anything under 5 was lost.


Yeah, I am using Accurip, printing through CorelDraw X7. I ran the droplet density test when I first fired things up, and I thought everything looked good... I guess it's possible I didn't know what to look for. Do you think tweaking the settings might change things? Right now, it's set at 1440 x 720 DPI, with a droplet weight of 5.


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## sben763 (May 17, 2009)

I recommend printing a few increasing the droplet (ink)until it starts to spread. different films can hold more ink without massive dot gain. 3 mil film cant hold as much as a 5 mil film. Also put the test films behind a light and see if you can see light in the spot color areas coming though.


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## earwicker7 (Oct 27, 2014)

sben763 said:


> I recommend printing a few increasing the droplet (ink)until it starts to spread. different films can hold more ink without massive dot gain. 3 mil film cant hold as much as a 5 mil film. Also put the test films behind a light and see if you can see light in the spot color areas coming though.


So when you say it starts to spread, do you mean that the test squares start to lose definition? I remember a mention somewhere in the instructions to watch out for ink that is still wet when it comes out of the printer.


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## sben763 (May 17, 2009)

earwicker7 said:


> So when you say it starts to spread, do you mean that the test squares start to lose definition? I remember a mention somewhere in the instructions to watch out for ink that is still wet when it comes out of the printer.


you don't want either, although if the ink looks wet, no edge definition loss and the rollers in the printer aren't taking off any ink. then go with it. I used filmmaker when I used a Rip and I had it cranked, I have used Accurip also and I just turn them up till there is excessive ink and back off to the last good print


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