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screen printing => Screen Making => Topic started by: jvanick on June 11, 2014, 10:30:53 PM

Title: image 'stretched' on the screen after exposure
Post by: jvanick on June 11, 2014, 10:30:53 PM
how does this happen?

I burned a pair of screens yesterday for a job we were going to print today (200 mesh)... nice clean burn, no problems, no wash out issues, nothing.

I couldn't get the job to register, no matter what I did...

finally in frustration, I pulled the screens and matched the films up to the screens.

sure enough, the underbase/white screen image was visibly stretched width-wise on the screen by nearly 1/16"... the other screen was perfect.

burned a fresh screen and all is fine, but wtf?

(I marked that screen for 1 color orders in the future only, but wondering if I should just put it in the remesh pile
Title: Re: image 'stretched' on the screen after exposure
Post by: GaryG on June 11, 2014, 10:51:01 PM
Seems like I've seen that with two different mesh counts, but both 200's, humm.
It's been frustrating here too at times. Tensions the same?
I'd like to see who knows other variables...
Title: Re: image 'stretched' on the screen after exposure
Post by: Frog on June 11, 2014, 11:17:47 PM
The only time I've experienced that was using the old ultra fast dry blockout from Southwestern. It seemed to actually shrink the screen.

If your screen was a retensionable, is there any chance that something slipped?
Title: Re: image 'stretched' on the screen after exposure
Post by: Homer on June 12, 2014, 07:04:21 AM
my guess is a warped screen, when the vacuum sucks it down, it distorts the mesh for exposure, then once released, back to "normal". set the screen on the glass on see if it's flat...if it's flat, maybe a thick build up of emulsion on the print side of the mesh causing it to not sit tight on the glass...

after thinking on it, I ran into this before and I believe our problem was heat from the light source shrinking the film, back when we used laser film...
Title: Re: image 'stretched' on the screen after exposure
Post by: 3Deep on June 12, 2014, 11:32:06 AM
I've burn warped screens and they registered just fine, I'm thinking more like the screen has let loose a little from the glue, I've had that happen or like some one mention the same could happen on a roller frame just enough to cuz a misregistration.

Title: Re: image 'stretched' on the screen after exposure
Post by: inkman996 on June 12, 2014, 11:34:32 AM
I've burn warped screens and they registered just fine, I'm thinking more like the screen has let loose a little from the glue, I've had that happen or like some one mention the same could happen on a roller frame just enough to cuz a misregistration.

Same here on warped screens. The vacuum flattens the screen to the film and the screen hangers flatten the screen to the platen so there really shouldn't be an issue there. But he said his imaged stretched versus shrunk which kind of rules out glue releasing.
Title: Re: image 'stretched' on the screen after exposure
Post by: Homer on June 12, 2014, 11:46:39 AM
welp, their goes my theory haha....
Title: Re: image 'stretched' on the screen after exposure
Post by: jvanick on June 12, 2014, 12:15:38 PM
wierd.. I just checked that frame ... it's perfectly flat... no bumps or drips on the emulsion.

however. what I did realize is that when the screen was drying post exposure, it was REALLY close to the space heater I use in the screen room.

wondering if the uneven drying temps caused something to happen to screen.

-J
Title: Re: image 'stretched' on the screen after exposure
Post by: jsheridan on June 12, 2014, 12:19:10 PM
, it was REALLY close to the space heater I use in the screen room.

wondering if the uneven drying temps caused something to happen to screen.

-J

yes it's been proven that heat causes a screen to shrink..

Mesh is after all a type of plastic.
Title: Re: image 'stretched' on the screen after exposure
Post by: Frog on June 12, 2014, 12:26:16 PM
, it was REALLY close to the space heater I use in the screen room.

wondering if the uneven drying temps caused something to happen to screen.

-J

yes it's been proven that heat causes a screen to shrink..

Mesh is after all a type of plastic.

I remember a place I worked (in the days of stapled mesh) that used this method to "re-tension" screens, LOL!
Title: Re: image 'stretched' on the screen after exposure
Post by: 3Deep on June 12, 2014, 02:19:59 PM
, it was REALLY close to the space heater I use in the screen room.

wondering if the uneven drying temps caused something to happen to screen.

-J

yes it's been proven that heat causes a screen to shrink..

 Ha Ha when I was a kid we would leave our basketball out in the sun to blow it up since we didn't have an air pump.

Mesh is after all a type of plastic.

I remember a place I worked (in the days of stapled mesh) that used this method to "re-tension" screens, LOL!