[teezecrost]

Hi, everyone. I've been printing for a while now, but had a completely discouraging print session last night and feel like a complete newbie again.

Most of my printing time has been on a 4-color press with no micros. Now that I'm on a press WITH micros, I'm experimenting with butt registration a lot more and I'm a little embarrassed to say I'm having some issues. I'll describe the job and maybe someone can shed some light for me. And sorry for the length of post!

Job: White underbase, small bits of red, small bits of peach, black outline, didn't bother with highlight white.

Problem 1: registration was pretty bang-on, but there was a sliver of overlap of black outline on top of peach portions. This seemed to create a blurry, muddy transition between the colors. Is there really 0 tolerance for registration misalignments? Or would the fact that I'm printing on an underbase make things more smearable?

Problem 2: I was having to flash after underbase of course, but then also after printing the red and peach colors because of a)the peach/black blur issue b)The black screen was lifting too much red and peach ink off the shirts. Do I need to lubricate the back of my black screen or something?

Problem 3: Getting a solid, thick print of black required a few squeegee strokes. But getting that nice looking outline also caused the black text to spread out become less readable. The text was on the underbase, and outline was printed directly on fabric. Is my problem that I should have knocked the text out of the underbase?

I'm sure what went wrong last night was a series of small issues, but it sure is frustrating and discouraging to fight a losing battle all night! Any advice would be much appreciated! Thanks in advance!

Design being printed can be found here:
http://mindfull.co/details.php?sku=1050

 

[tlbays]

Hi Rob

Several of your issues regard the ink layer thicknesses being printed,
and mesh count info would benefit trouble-shooting.

The contrast of printing on a sealed "vinyl" surface vs. absorbent fabric
is often leveled out using a thin underlay + highlight spot white. (175t + 175t, for example)
You seemed hesitant towards that approach?

-Note that some black inks have better trapping ability that others.
-Sharp stencil image edge definition and "good" screen tension are also beneficial.

Here's one optional approach to engineering:
Underlay / flash / spot peach / spot red / spot white / flash / black

Given your well thought out post, I'd say you're almost there.

Happy trails!

 

[teezecrost]

Thanks, Screen Outlaw. For mesh counts I was doing 160 underbase with 230 for each other color. I'd like to go finer with the underbase, but my white ink is so thick, I don't think I'd ever get an even coat out of it!

Sorry, what does 175t convert to in imperial units?

I wasn't hesitant about the highlight white for any particular reason. Just trying to save some setup and cleanup time really.

I'm using Excalibur inks right now. I think I'm going to switch to wilflex next time around and see how that helps!

 

[teezecrost]

Any further input people have for me would be very much appreciated!

 

[CNClark]

What kind of screens are using? It is imperative that your screens are tensioned pretty high for butt reg and they should also be withim a few Newtons of each other....at least in my experience. Secondly, are you printing on a manual? If so, you need to understand that no matter how good you are, you can not manually print with the same pressure, same squeegee angle on every stroke. you must have an auto to do accurately control those variables. Everytime you put down a little more pressure than the other strokes, it can lead to that muddy mess you are referring to. Butt reg is great, and we use it alot, but it requires you have all the variables in order to do it successfully.

Another thing to consider, is if often time a 156 mesh screen has a higher tension than a 230, so right there, assuming you are using the same pressures on all heads, one screen is going to stretch more than the others. Try using the same mesh for all your screens and adding that highlite white. Base out or reduce your white so that it will go through that 230 mesh...we use Wilflex quick white with about 10% soft hand as a underbase white. You can also use a thin grey ink to underbase then use a highlite white.

 

[CNClark]

Also half-toning your underbase can help with keeping the color where they should be. We underbase at 80%...60lpi

 

[teezecrost]

Thanks, CNClark! Great info. This is actually my first run using retensionables. I did tension and retension them as per newman's chart.
What about the part with the colors lifting onto the back of the black screen? Is there such a thing as lurbricant for screens? Or am I barking up the wrong tree there?

 

[CNClark]

Some inks build up more than others....I'm not familiar with Excalibur ink, I'm pretty much all Wilflex and some Union. Another build up issue is from lack of tension on screens. Some of your problem with that maybe you are laying down too thick of an underbase. One pass through a 230 with an extended white at 80%, even doing a half-tone underbase through a 160 will help alot. You will have to experiment with inks to find one that suits you the best, call around and get samples, they hand them out like candy. Do you have a tension meter? If so, what newtons are your screens sitting at?

As for the multiple passes of black you are needing, that is could be due to poor printing mechanics, not enough pressure, or wrong angle, it could also go back to tension. Are you pushing or pulling the squeegee?

 

[CNClark]

ANd yes, some people use silicon sprayed on the substrate side of the screen in order to work around the problem you are having with buildup. However, that is a bandaid. I would experiment and find the underlying problem that is causing this. In 12 years in this business and millions of shirts printed, I've never sprayed silicon on the back of a screen.

 

[teezecrost]

Yeah, I didn't think a spray would be required.

I'll have to check on my screen tensions when I can get to them, but I think 24 newtons sounds about right for the 200s. I do remember that I couldn't get it the same in all areas of the screen. The tension was lowest by far towards the square bar.

I'm doing pull strokes every time.

Thanks for the advice so far! I think I'll try the halftoned underbase as step one, and maybe vary the stroke technique a bit.

 

[tlbays]

Hi Rob

CNClark is quite right about limiting variables.

When time or expense gets in the way of complete control, there are some "band aid" fixes that can help compensate for specific problems.

For example purposes only (this type of product is also available from all larger ink producers):
Build-Up Buster
It helps to reduce the viscosity and tackiness of plastisols.

Silicone Spray is a "band aid" fix occasionally employed onto a following screen underside
to reduce tack of a flashed ink surface coming in contact which is not allowed to cool sufficiently.

....back from the South 40.
Happy trails!

 

[CNClark]

Do yourself a favor and learn how to push the squeegee instead of pull it. Your body and arms adapt to pushing much easier than they do pulling..it is way easier on you. A little known fact is that it also produces a better product and you have alot more control over the blade when pushing. I read an article recently that had all the physics of pushing v. pulling and why pushing is superior...

 

[teezecrost]

Oh, that's excellent. Is there any trick to it? things to watch out for? Use same angles etc?
Thanks!

 

[tlbays]

Here's the detail that CNClark is probably referring to, for further investigation:
Pushing vs. Pulling in Manual Screen Printing | ScreenWeb | screenweb.com

Around our customer base, I'd say ave. 3 out of 10 manual press printers use a push stroke.
I'm am always amazed at how rarely height adjustments to the base of the press are made also.
....but I think I'm drifting off-topic.

Good luck to all.