Author Topic: what causes 'chatter' breakdown?  (Read 6369 times)

Offline JBLUE

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Re: what causes 'chatter' breakdown?
« Reply #30 on: November 17, 2015, 11:20:00 PM »
Got something that works well on a Nuarc 3140? 

Currently exposure times with the Saati PHU are 170 ltu for plastisol screens and 200 for waterbase screens for the Sure Loc 150/54 Murakami panels coated 2/2 sharp side with the PHU.  If you have something comparable I would love to try it out!

You have something funny going on I think. We run a 3 k and a 150-S coated 1 shirt side and 2 squeegee side are exposing PHU in 28 LTU. We run a little on the thick side too for a stencil. That is a pretty dead on exposure. Finish off with an hour in the sun after block out and we run10k impressions with no hardener or breakdown.
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Offline Colin

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Re: what causes 'chatter' breakdown?
« Reply #31 on: November 18, 2015, 09:24:22 AM »
Got something that works well on a Nuarc 3140? 

Currently exposure times with the Saati PHU are 170 ltu for plastisol screens and 200 for waterbase screens for the Sure Loc 150/54 Murakami panels coated 2/2 sharp side with the PHU.  If you have something comparable I would love to try it out!

You have something funny going on I think. We run a 3 k and a 150-S coated 1 shirt side and 2 squeegee side are exposing PHU in 28 LTU. We run a little on the thick side too for a stencil. That is a pretty dead on exposure. Finish off with an hour in the sun after block out and we run10k impressions with no hardener or breakdown.

Actually we did have something funny going on.....

Exposure times are now at about 60 ltu for that same mesh with the same emulsion.

The key was - INSTALL YOUR BULB IN THE CORRECT MANNER...........

The last guy we had in the screen room put a new bulb in UPSIDE DOWN.... yea, its a real thing.  We installed a new one, correct side up and exposures dropped by 1/2 to 2/3.....

Frikin nuts man.....
Been in the industry since 1996.  5+ years with QCM Inks.  Been a part of shops of all sizes and abilities both as a printer and as an Artist/separator.  I am now the Ink and Chemical Product Manager at Ryonet.

Offline ZooCity

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Re: what causes 'chatter' breakdown?
« Reply #32 on: December 21, 2015, 03:02:56 PM »
Walt from Murakami sent us out some SP1400W.  So far it's been the solution to our chatter problems!  SP1400 seems like a great all around emulsion to boot, we're going to do res tests on it next month. 

In case this wasn't mentioned this emulsion is freeze/thaw stable. 

Offline JBLUE

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Re: what causes 'chatter' breakdown?
« Reply #33 on: December 21, 2015, 09:53:17 PM »
Hmm.  Using Saati PHU our 3140 has us exposing at 150 ltu for plastisol and 180 ltu for waterbase.  Yellow 150/54  sure lock panels.  Gets us a solid step 7 @ 150 ltu.

But we coat 2/2 sharp side.

Thats some pretty crazy times. We expose PHU for 25 LTU on a 3 k light and thats more than enough. PHU loves the sun. 30 minutes in the sun after exposing and we have never had an issue. The only time I have had chatter arks was with SP1400.
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Offline jvanick

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Re: what causes 'chatter' breakdown?
« Reply #34 on: December 21, 2015, 10:49:05 PM »
when we switched from SP1400-W back to SP1400 the starlight and that emulsion didn't mix well for us here... we were getting very unpredictable results depending on who the hell knows what... which made us start to look for other emulsions...

We switched to PHU .. it was too fast (160S screens were at 3 seconds! to a solid 7)... so we switched to PHU2... (160S at 12 seconds)... we started getting some weird chatter type breakdown sometimes depending on the shirts, pressure, etc...

we did more research (Ross Balfour from Saati involved)... and found that we were coating screens way too thick.. on S-mesh we found that a single round edge coat on the shirt side was plenty to get us to 18-20% EOM.

After we made that simple change (which has saved us a LOT in emulsion as well), we're now running 1000+ piece discharge runs with PHU-2 (with proper post exposure) with all the easy reclaim of a pure-photopolymer.  Honestly couldn't be happier with how it's working out.

JBLUE is right tho on that the Saati PHU emulsions love the sun or post-exposure... after a bunch of testing, I don't even think that the LED units gives the right wavelengths for proper post exposure, as I can put 3 screens on the same long-run job (1 post exposed on the Starlight, 1 post exposed on Saati's 300W lamp, 1 post exposed in the sun) and the best looking screen at the end of the job will be the sun post-exposed one, followed by the Saati 300W one, followed very closely by the starlight....
« Last Edit: December 22, 2015, 10:05:21 AM by jvanick »

Offline Frog

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Re: what causes 'chatter' breakdown?
« Reply #35 on: December 22, 2015, 09:52:18 AM »
On most days, 30 minutes in the sun has to be the equivalent of hours in any exposure unit.
But, perhaps 5 minutes would have had similar effect. There has to be a point at which all molecules are cross-linked, and further exposure is merely recreational sun tanning.
That rug really tied the room together, did it not?

Offline ScreenPrinter123

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Re: what causes 'chatter' breakdown?
« Reply #36 on: December 22, 2015, 10:22:26 AM »
Sounds like you need to move to the Gulf Coast...problem solved!