[brent]

Hi Guys,
I don't know how long it's really been going on, but today I did a three color that had butt registration and the films lined up properly but the screens didn't, leaving a gap between the colors that isn't in the artwork or on the films. Dennis at Westix said it could be because I'm burning too long, but I reduced my burning time 33% and it still occurred.
Does anyone have any ideas why this happens? I have a Hix tt180 table top exposure unit with a vacuum lid, print my films with an Epson 3000, and the screens in question today were 160 mesh.
Any ideas would be great. I did the print run today, but it didn't look perfect because of this problem...

 

[neato]

Check your films again. Make sure they are dead on after the burn and that they didn't shrink at all from the heat.

 

[brent]

They didn't shrink. I lined up the films after the print run was all done... Maybe my vacuum blanket isn't holding things down perfectly? That'd be crappy but I assume I could fix it. I'll call westix about it tomorrow. I need to do a 4color soon and it has to be perfect, very picky customer.

Anyone else had a similar problem?

 

[jpspent]

Try putting a flat board with a weight over the image your trying to burn so that the screen is flush to the film and exposure unit. The board should fit inside the screen on top of your exposure blanket. Double check your screens, if your using wood screens they could be warped
letting light in between the film and the screen.lol

 

[Catbox]

maybe the screens are loose? just a shot...lol

 

[brent]

The screens are not use. It's an exposure unit with a vacuum blanket so Jeff's proposal doesn't really make sense. I just put a screen in and turned on the vacuum to make sure the rubber blanket is held down as tight as possible, and it is.
The problem is that the stencils are being created smaller than the design is on the film so they don't butt properly.

 

[jeffie]

Hey, yikes sounds like screen tensions may be different, or off contact, or press regerstration,...or the list goes on... a little more info might help...is the prob in all diminsions or??does one platen print diff than others or not...jeff

 

[jpspent]

While your vacuum may seem tight and your image is still shrinking added weight to insure your positives are flush couldn't hurt. Sounds like over exposure or film density might be an issue as well.

 

[brent]

Monday I'll do some test burns... I'll add some weight on top the vacuum blanket, and I'll make sure that the vacuum unit is working properly. I will play around with exposure time too.
Thanks for the info and ideas, everyone.

 

[majen]

Are you shooting emulsion to emulsion? In other words is the side of the film with the image on it contacting your screen? If it's not then the thickness of the film can get the light to scatter enough to cause this. Also, yellow or white mesh?

 

[brent]

white mesh. this is happening for sure with 160's but maybe others. It's the same film I've always used. Printing from an epson 3000 and the print side of the film does touch the emulsion.

 

[majen]

Could maybe then be the white mesh. Have you always used white mesh and if so is has this always been an issue? Yellow mesh will increase exposure time a bit but your images will be more accurate.

Other than that, not sure. Everyone else has covered the other possible causes.

Is the image actually shrunk on the screens or just when you print?

 

[brent]

I think I may have just been burning way too long. I need to burn a screen Monday, a 160, just to compare to the original film. It's not lining up right during registration, I don't think the print is shrinking and not butting properly during printing only due to off contact.