Off Contact & Micro Reg

[upperhandprinting]

Hopefully this is in the correct area on the forum.

I'm setting up a job right now that will be printed on white tanks. It's a 2 color spot job using red and black. I had a few issues with this job, so bare with me and the length of this post.

1. Registration was off. Here is how I burned the screens. I had my films printed and they lined up perfectly. I burned the red screen first, waited for it to dry, and then placed the other film (for the black screen) on the already burned red screen to line up where it would need to be to line up correctly. I then burned my black screen with the film in the same spot where it lined up on the red screen. Thinking this was a sure fire way for them to be extremely close when I got on press. I centered the red screen on press and did a test print, flash cured it and then went to register the black screen to it. No matter what I tried, I couldn't get them to line up all the way around. When one spot was lined up, the other side wasn't, and vice versa. Since I know the films lined up, it became very frustrating that they weren't lining up on the press. The only thing that I can think of as to why they won't register is that after I printed the red and flashed it, that the garment shrunk from the heat. The garments are 100% cotton and I know Jonathan warned of this in one video. Is there any other reason as to why it wouldn't line up? And I know Jonathan suggested putting the blank garment under the flash first to shrink it before you print anything, but could I put the whole run through my oven to shrink them quicker? and then print normally? I will flash them to shrink if that will work best, just trying to figure out the most efficient way to do it. Also, if you have any other ideas as to why they won't line up, any and all suggestions are welcome.

2. Off contact. I tried setting it to 1/8" and it's still putting down way too much ink. It also pushed through to the inside of the shirt, even getting a bit of ink of the pallet. Is that an issue of off contact or does that have more to do with squeegee pressure?

Thanks for the help guys!

[ApeShirt]

Interesting. My thought would be shrinkage is the issue. I haven't ran into that problem yet myself. I'm also guessing your squeegee pressure and angle is too much. I had that happen once but changed my angle and pressure and it was fixed. It's like your pushing the ink into the garment instead of on it. I'm not sure if how many layers of emulsion on a screen plays a factor. Seems like it could potentially be. A thicker stencil lays more inks so that could play into it.
I'd love to hear from a more experienced printer here.

[upperhandprinting]

I still had the screens on the press the other day, so I tried it again, but this time I pre shrunk the shirt with the flash curer. The image lined up pretty much perfect. But I did notice another error that has caused me to have to reclaim both screens and start the image over. It never really occurred to me that the placement of the design on the screen plays a big role on other things, but this has taught me that. This image was just about as big as a 20x24 screen can handle, and I put it too low on the screen. The whole image fit on the screen, but when I went to press, the bottom of the image ran off the pallet. If I moved the pallet back, it would hit on it, but then the images didn't line up. So it was a battle and now I'm reburning the screens. Thanks for the help, but the registration wasn't really the issue, just bad transparency placement.

My registration has been giving me trouble though. Today I was printing a simple text. 2 colors, with a fill and stroke. The registration seemed to be okay, but the stroke almost seemed to bleed over the letter and become too wide of a stroke. Do you think this is caused by having my stencil too wide in the first place, with too much overlap on the fill and stroke? Or do you think it is too much squeegee angle/pressure? I've been fighting with it. One print looks great, the next is off and bad looking. Consistency is a big thing I'm trying to gain and it's alluding me right now.

Thanks!

[Catspit Productions]

It sounds like to me the most likely cause of the issues you are experiencing here are a combination of your flood stroke and the stencil being too large for the screen. On any given size screen there is what we call a sweet spot. That will tend to be the center of the screen. You do not want to max out designs on a 20 x 24 screen with a design that goes nearly all the way to the edges of the inside of the frame. The tension in the middle of the screen will be different than that of near the edges. This alone can cause registration problems.

If your designs are so large that they are taking up most of the screen on a 20 x 24 then you should move up to the next size which would be a 23 x 31 automatic frame. Your stencil should never be too close to the edge of the frame. You should have at least 2 inches to spare between the stencil and the frame edges. More would be better as the center of any screen will be the sweet spot for printing.

Also it is important to note and remember that it is not only the garment that can shrink but also plastisol inks can also have shrinkage problems. Some plastisol inks will actually shrink during the flash so it is important to determine which is shrinking. The shirt, the ink or both. Normally plastisol inks will shrink before a 100% cotton shirt has the time to shrink from heat. If you're using water-based inks this may not apply.

In summary as I said I believe the problem is a combination of having too large of a stencil on a small screen while having to push your flood and stroke harder in order to compensate for the differences in tension from frame edge to the middle of the screen to frame edge.

I think if you reduce the stencil size for the 20 x 24 screen or increase the screen size you will find that your flooding and stroking will be much easier and more consistent. This will also reduce any distortion that may be caused by having too large of a stencil on too small of a screen. That should certainly eliminate any registration problems and it will also allow you to perfect your flood and stroke.

As for shrinkage that is easily minimized or eliminated by reducing the time under the flash cure unit. You only need it to be dry to the touch not cured fully.

Good luck and let me know if that helped you out any.