Alcohol free printing - Issues

[Lukew]

We are running alcohol free on polyester plates with a shino 52.
The issue we are having is the very lead edge of the plate on the corners of what ever size sheet we are printing, is inking up.
Usually when running with alcohol we would have a 1mm ink stripe along the lead edge of the plate while running, but now on the corners the ink will build up to the point it starts working its way into the job. To stop this the fount dials need to be turned up but this then means there is too much damp over the rest of the job.

It doesn't matter how much you skew the metering rollers, the problem is still there.

The problem is worse the faster you run the machine. once it gets to 13500 sph it becomes a real issue especially on Uncoated stocks.
We need to be able to run at full speed 15000 sph+

Normally IPA free the issue you have is too much damp on the outer edges of the sheet..

I'm thinking possibly the fount isn't designed to run at that speed, anyone have any idea's?

Regards...

 

[nhprinter]

Hi Luke,

A lot of questions need to be answered.

Is this a new switch-over for you? (from IPA to Sub)

Are you running the same rollers you ran with IPA? (Should be softer)

How old are they?

What's your conductivity? pH?

Are you using a 1 step or FS and sub?


Dave

 

[Lukew]

Is this a new switch-over for you? (from IPA to Sub) effectively a 2 year reduction down to zero

Are you running the same rollers you ran with IPA? (Should be softer) same ink rollers, softer water forms, metering rollers are harder then what they should be .

How old are they? Water forms 1.5 months, metering rollers 10 months, all ink rollers 5.5 years (don't ask why) I have a feeling that the shore A hardness of the ink forms is causing some of the issue, but why only on the ends and why with alcohol is there no such issue?

What's your conductivity? pH? with in range of this particular fount.

Are you using a 1 step or FS and sub? 1 step only.

 

[Joe Duffy]

All rollers with contact to the fount should have been changed when you switched from IPA to Sub. There is a residual hold over in the rollers from the IPA and it will continue to cause issues until they are switched. I ran sub and 1 step on a Diddie and ABDick 9850's with poly plates so I was running at all kinds of various speeds and I changed all rollers out and found the balance. I had to run more fount than was asked for to hold a clean print but my conductivity remained in the area asked for.

 

[Cornishpastythighs]

I'm not familiar with your press but am very familiar with going Alcohol free. Way back in the day they told us we were going alcohol free so we dumped the tanks filled up with new fountain solution measured the conductivity and promptly ran shifts of colour variation and scrap. All the things that alcohol had been covering up suddenly came to light.
Go back to your basics, Roller settings, Durometers,Temperatures, cleanliness. You may have to experiment a bit to find your 'sweet spot' but it will make you a much better printer.
Good Luck

 

[erictoray]

What you may have going on here is a roller setting that is too strong or possibly too hard to work with the Alcohol free solution.
Try to reduce your the stripe width on the first form that hits the plate down to 3-4 mm in width and if you can check the hardness of the roller.
Back in the day when alcohol free and subs came out, rollers needed to be in the 24-28 Shore A hardness.
BTW, what is the mixture of fountain solution to substitute?

Regards,
Cousin E

 

[Dan Roll]

If your press has the standard Shinohara three roller dampener, make sure you set the pan roller to form roller pressure to the lightest pressure setting you can achieve and still have the dampener transfer water evenly. On some Shinoharas this is difficult to set as the bracket design has the roller in a different position (and pressure) when the press is running than when it is not.

 

[bullibrad]

Luke,

We also have a 4 col Shino 52. We have been running successfully alcohol free for 10 years, firstly with our Heidelberg machines and since 2009 with our new shino 52.

We use GSB Chemicals Alpha Blue and dose at about 1%. Admit-ably, our dampening rollers are replaced every year or sooner.

We have workout a great way to set our dampening.

Regards,
Brad

 

[Lukew]

Luke,

We also have a 4 col Shino 52. We have been running successfully alcohol free for 10 years, firstly with our Heidelberg machines and since 2009 with our new shino 52.

We use GSB Chemicals Alpha Blue and dose at about 1%. Admit-ably, our dampening rollers are replaced every year or sooner.

We have workout a great way to set our dampening.

Regards,
Brad

Brad could you let on how you set the dampening rollers please?
Do you run metal or poly plates?

We have changed our water form rollers from the standard 25 - 28 shore hardness roller, down to a 22 shore A hardness. This widened the operating window a lot, and stopped the water beading between the chrome and water form roller on start up or press stops.

Please note: If the press is run under 13000 sph there isn't an issue with outside paper size lead edge corner scumming. Its as soon as you push it past that speed.

 

[Lukew]

Thanks for all the input, I have tried various % dosage of the fount. Various roller settings, the issue still stands.
I have now dosed in 2% alcohol and the issue has gone away.
Is it possible that the old hard shore A harness ink forms are splitting/breaking the alcohol free fountain solution at the lead edge of the plate as the rollers come out of the plate gap?

We will be trialing another fount next month, if that does the same thing we will have to run a small % of alcohol until rollers are changed.

 

[bullibrad]

Luke,

I am sorry I did not get a chance yesterday to talk to the head printer. I know we trialled a few alcofree products but found the GSB Alpha Blue to be the best. We run the chiller as high as we can which I think is about 19 degrees cel. I read somewhere that was better for alcofree solutions. We are running metal plates and have no experience with paper or poly (just check the plate packing is not worn ever so slightly where you are getting the problem). We are currently running USA Pacesetter rollers which seem fine. We were not aware of anyone that has/had exchange based shafts for the shinos.
To set the metering roller and skew, we use a set of plates each with a 40mm wide band each in cmyk and colourbars, have the ink keys all open evenly and make adjustments only to the water pressures until its even across the sheet on the spectro.

Regards,
Brad

 

[Alois Senefelder]

Wrong

Wrong

Hello Bullibrad,

Correction: Irrespective of using IPA or Alcohol -Free Concentrates in Fountain Solutions, the Chillers should be set to run the outflow temperature of F.S. 10/12 degrees Celsius.

2) The last answer you gave is - Bamboozle


Regards, Alois

 

[Lukew]

Alois: according to all the modern up to date literature, The current alcohol free fountain solutions work best at a higher degree of celsius, 15 deg is generally the recommended starting point. If it is too cold then there can be shocking of the fountain solution when it meets the rollers/plate.

The only reason you run at 10 - 12 deg celsius with IPA is to help keep it suspended in the fountain solution and reduce it's evaporation rate.

Bullibrad, that is an odd way you go about setting the metering roller, as generally during operation especially on longer you will be opening up the metering roller on the gear side a little due to heat to stop scumming up.

From memory with alcohol the metering roller should be set to flood then tighten until no flooding then go 1.5 turns extra. But with alcohol free you should set it to flood then tighten until no flood then tighten .5 turn extra.

The water form to chrome on the shino is meant to be 3mm and water form to plate 4mm. This makes no sense as the plate is going to end up over riding the water form gear and drive the water form at a different speed. I have set the soft water form to chrome at 3.5mm and set the water form to plate at 2.5mm - 3mm

 

[bullibrad]

Luke,

Shino manufactured around 2009 or at least ours has an issues with the metering roller being out of parallel to the steel. To do a rough quick set without setting using the plate method I mentioned, we end up .5 turn on operator side and 1.5 turns on drive side. Which as you can imagine means we replace the metering roller every 6 months, and need to reset / check regularly.

 

[tchelsa]

Hi,

Dan you are right. I have already faced the same.

...C

 

[RGPW17100]

We had a similar problem years ago when I ran a 52 4 color shino. We tried using pink fountain with al sub but scumming would not go away. We used total fountain however this fountain seemed strong and tended to wear out the plates after about 5000 impressions. We also had issues using a local roller vendor who was using the wrong durameter. Bottcher came in and measured the rollers and got me new ones and the plate ran a lot drier. My problem with the old roller is I could not drop the water low enough to get my ink densities. Good luck. FYI this was almost 10 years ago so the fountain might have changed

 

[Tech-Service Press]

This might not have anything to do with the dampening solution. Your problem description suggests that the ink is drying on the ends of the rollers on long runs using non-metal plate.
Ink needs better stability (less drier and more anti-oxident) especially with high speed on long runs.

 

[Sustainable]

This might not have anything to do with the dampening solution. Your problem description suggests that the ink is drying on the ends of the rollers on long runs using non-metal plate.
Ink needs better stability (less drier and more anti-oxident) especially with high speed on long runs.

The ink is semipolymerizing it is bouncing between a state of stablity and semi drying. Tech-Service is absolutly correct.

 

[Lukew]

The ink is semipolymerizing it is bouncing between a state of stablity and semi drying. Tech-Service is absolutly correct.

I was wondering if this could be the issue!!!
Although I thought since this particular fount had a 70% glycol content in concentrate, it wouldn't be likely. Also a whole range of inks do it. We had been using Vanson VS3 which is a slower drying ink anyway.
We have just changed founts, so it will be interesting to see if the issue goes away.
If it happens with this fount, I have an ink that has near zero dryer in it so I will put it in to see if the problem goes away.

I also thought perhaps the metering rollers have some swelling on the ends.

Thanks everyone for your input, greatly appreciated.

 

[Lukew]

The ink is semipolymerizing it is bouncing between a state of stablity and semi drying. Tech-Service is absolutly correct.

I think you have found our problem, thankyou for that. All I need to do is now find out what can be added to the the hundreds of kilo's of ink we have used without issue when running high alocohol. I pressume an ink supplier should be able to supply an antioxident to add to the ink.

ON a side note, the new fount did the same, so we are up to 4% IPA now while we wait for new dampening rollers to arrive,
We are noticing massive picture framing when using fast dry inks on longer runs, I assume this is caused from the semipolymerizing of the ink?