Cannot get multi-color jobs to register. Something is shifting during the run.

[Hey Monkey]

Hey flatstock printers! Beyond frustrated lately. Cannot seem to get multi-color jobs registered correctly. I am on a DIY vacuum table, speedball clamps. Off-contact is good. Generally using 230 mesh screens. Sometimes 305 if it is high-detail work. Newer screens and I take good care of them. Aluminum frame.

A few questions...

1. Anyone have issues with their speedball (or other) clamps not gripping the screen? It seems the screen may being moving ever so slightly during the print run on the first color thus making the second almost impossible to register as it appears the print shifts throughout the run.

2. Push or pull stroke? Does it matter? I tend to use a push stroke. I find I get more consistent prints that way at least when I print textiles.

3. Registration guides. I use little plastic ones that the paper can slide into to lock it in on the table better. What do you guys use? How may reg guides to you place on the table to ensure it hits the spot each time?

4. Vacuum. I use a Eureka RV canister vac. When building the table we did not put spacers in the table as it was a heavy piece of MDF so it didn't need the support but perhaps not putting them in is decreasing the suction (it seems a lot of DIY tables have them.)

Of course without seeing the issues I know it is hard to diagnose but I am at my wit's end here so I thought I would ask you all and see what comes of it. Something is shifting somewhere throughout the runs.

If you don't mind taking the time to tell me your process for registering multi-color runs I would appreciate it!

[GaryG]

First thing I would ask is how is your screen tension?
What kind of paper? Shrinking, distorting when "ink dries" pulling in different directions?
Push stroke also puts more ripple pressure on mesh than pull.
Aluminum frame may let clamp slip, especially with push stroke.
Insert paper...then activate vacuum.

These are the guides we used to use: they are as you know, 2 on the long side of substrate, one on short side
a few inches from corner.

-AWT on far right
http://www.anthemprintingsf.com/Screen-Printing-Tools-of-the-Trade-s/128.htm

[im_mcguire]

Well as far as I can say, my speedball clamps are crap. I've done only a handful of jobs for flatstock, but I noticed the clamps moving when I lift and lower the screen. I decided to stop using them, and make a vacuum rig on my manual shirt press. It works for what I need, but it's not ideal.

[Frog]

I was going to recommend the venerable Jiffy Clamp, around since at least 1970 when I got my first pair. Used in a lot of shops over the years.
Thing is, I don't believe that they look a lot better than the Speedballs I see in pics (unless there is play in the Speedball hinge itself)
I really think that as Gary G mentioned, the issue could well be that these may not be grabbing these new-fangled aluminum frames as well as the wooden ones which were the standard back in the day. Now, in flatstock shops I have worked, we have used the hinge/aluminum frame combo, but the stuff I ran rarely demanded really tight registration.

Thing is though, not unlike a rear clamp manual, these should be capable of staying secure. Perhaps you are afraid of overtightening? If I had eliminated loose mesh/too much printing pressure, secure reg tabs, and paper shrinkage as the culprits.  I'd add some of that high friction rubber mesh matting like we use under futon pads and in toolbox drawers. Heck, I might use it no matter what as SOP

[Hey Monkey]

Thank you everyone!

My screen tension is good. I do push stroke as it just seems to work better for me on my shirts but will play with pull more when I do flatstock. I am going to add a third clamp in the middle and the sticky drawer liner stuff.

Another printer buddy of mine said he took the wingnut off of his clamps and replaced with brass nuts and washers and uses a wrench to tighten and hasn't had a slip issue since. So I think a combo of what you all recommend and that will stop that screen from moving.

I do acclimate my paper (French Paper) at least 24 hours. Maybe longer? My shop does have AC and Heat and stays pretty constant in temp and humidity so that helps.

Thanks everyone! I will report back!

[RICK STEFANICK]

The first thing i would look at is making sure your guides or whatever your using are in the exact same spot for all the colors.

[Hey Monkey]

The first thing i would look at is making sure your guides or whatever your using are in the exact same spot for all the colors.

A little different for the flatstock as you change screens between each color. Only a one station press as you don't print wet on wet for paper. So you swap screens, lock in the new one then register the paper to that screen. So there are subtle shifts between colors regardless.

[Sbrem]

most clamps are OK for one color work, but are too sloppy for multi color; this means your first color down is not in the same place on each sheet. To combat this in the old days when we did this kind of work, we would block the screen on the 3 sides not being held by the clamps, so when you put the screen down, it's locked into the same  place every time, ditto for the rest of the colors. Then, providing the clamps are in the back, pull the stroke, this will work, but you may have to start over if your first color down is moving around, you would never get the remaining colors to line up...

Steve

[Ross_S]

Stupid question here.  Are you building in traps to the art so each color over prints slightly to avoid this.

Ross

[mimosatexas]

I print a decent amount of flatstock using hingeclamps and everyone is pretty dead on so far in the thread.  You need to trap the art more than on a shirt, both due to the tolerances of the clamps and due to the fickle nature of large sheets of paper when you saturate them with ink. Stop blocks can absolutely help with left right shifts through a longer run if your clamps are wiggling.  Pull stroke is usually better for flatstock with waterbased in my experience and I ONLY push on shirts as well.

The speedball hingeclamps are indeed crap, and often have issues with the way the threads interact with the actual clamp which can cause mid run shifts.  You can try over tightening using a pair of pliers to get leverage on the wingnut to help a bit, but otherwise I would look into a higher quality clamp.  None of them are perfect though.  If you have the time and space, you might look into building a master frame instead with higher quality hinges welded or bolted and glued to it, and using an adjustable side clamp inside the master frame.  It will make positioning subsequent colors easier and prevent all the side to side shifting.

[RICK STEFANICK]

The first thing i would look at is making sure your guides or whatever your using are in the exact same spot for all the colors.

A little different for the flatstock as you change screens between each color. Only a one station press as you don't print wet on wet for paper. So you swap screens, lock in the new one then register the paper to that screen. So there are subtle shifts between colors regardless.

I realize that. but from my exp. printing posters if my guides were not in the exact same place for each color .usually 2 on the bottom and one on the sde you could have registration issues..just sayin

[rusty]

I have just started doing a lot of flatstock. a couple of things...

- are you "racking" your paper before you print? That means taking it out of the box/wrapper the day before you print and putting them on your drying racks and letting them settle to the humidity. I've printed straight out of the box only to have the registration go totally off.

- are you registering the paper to the screen and not the screen to the paper? If you are registering the screen to the paper you are giving it a chance to move on you. And it defintely will.

- I use the pins and tabs method a lot as I am still building a vacuum table for myself. Is that what you are using? I have the tabs on the three sides so I get best registration but it's never absolute so like everyone else said defintely build traps into your artwork just make sure your color order is correct and you can hide the traps. I just learned that mistake on an 8 color poster.

just to add for no reason. I always do the 409 trick before a print run. You do a light spray of 409 (must have ammonia in it) and wipe it down with a dry sponge. do a few passes with a dry squeegee and it really helps with sealing up the screen and giving a nice glide when printing. Don't know why but I never have any drying issues.

Also I mix all my colors with speedball and then mix in about 40% of TW 5000 ink.

[Doug B]

  All of the above and your off contact must be the same on every color.
Even if your screens have the same tension, one that's a little twisted
can and will affect the off contact and therefore registration. Clamps first
then guides and after you rule those out try everything else mentioned above.

[Hey Monkey]

Stupid question here.  Are you building in traps to the art so each color over prints slightly to avoid this.

Ross

Haha Not stupid at all! When it calls for it yes I am. Sometime though the client (or myself) does not want that faint halo that can happen with trapping. And even with I was getting pretty far off results and now am almost sure it was the screen moving during print.

[Hey Monkey]

I have just started doing a lot of flatstock. a couple of things...

- are you "racking" your paper before you print? That means taking it out of the box/wrapper the day before you print and putting them on your drying racks and letting them settle to the humidity. I've printed straight out of the box only to have the registration go totally off.

- are you registering the paper to the screen and not the screen to the paper? If you are registering the screen to the paper you are giving it a chance to move on you. And it defintely will.

- I use the pins and tabs method a lot as I am still building a vacuum table for myself. Is that what you are using? I have the tabs on the three sides so I get best registration but it's never absolute so like everyone else said defintely build traps into your artwork just make sure your color order is correct and you can hide the traps. I just learned that mistake on an 8 color poster.

just to add for no reason. I always do the 409 trick before a print run. You do a light spray of 409 (must have ammonia in it) and wipe it down with a dry sponge. do a few passes with a dry squeegee and it really helps with sealing up the screen and giving a nice glide when printing. Don't know why but I never have any drying issues.

Also I mix all my colors with speedball and then mix in about 40% of TW 5000 ink.

Hey Rusty -

Paper to screen. And I will work on larger trapping as well in the future. Where do you get your TW Ink from? I am on the East Coast (NC) Thanks!