chemistry?

[joe stag]

Once again with a different problem on this xl-75. We have been having issues with gear side drying and getting a proper ratio without emulsifying. All roller settings have been checked and rechecked but still can't get a clean plate without flooding part of the job. Only thing i can figure is the chemistry is off. We are useing 3oz per gallon each of a 2 step saphira system. Cond is around 3000 and ph 5.5. Any thoughts?

 

[aqazi81]

Have you checked the skew setting of the pan roller? Also the pan roller comes with crowning, make sure the pan roller is according to specs.
Try running with intermediate Z roller off from inking roller and see if you get better results.
Conductivity is high assuming you are running with IPA.
What is the water temperature?

 

[joe stag]

Water temp is set at 55 with 5 degree limit. I am running without integration. Unless i am confused isn't the skew setting what i set when i contact the chrome metering roller? Set till heavy water disappears plus a quarter turn. This happens on all units all on the gear side.

 

[aqazi81]

I'm not familiar with the XL75 dampening system but Skew setting is for Pan roller and it is used for controlling the water at plate sides. You can refer to the operating manual for better understanding.

 

[aqazi81]

One more thing to add, if you have an infrared thermometer, you can measure the water temperature in the water pan on DS and OS and see if there is any difference.

 

[joe stag]

On this press the pan roller is rubber like metering rollers on other presses and the chrome is outside the pan. Its new to me ive only seen them the other way around. There is no scew setting only adjustments for both sides. The problem is that the gear side has to be backed off so far to clean the plate that it starts accepting ink due to the volume of water when left that loose.

 

[Alois Senefelder]

Plate Dampening !


Hello joe stag and aqazi81


Chemistry is an important part of enriched F.S. BUT plays no part in the "Mechanics of Water Conveyance Systems"

The press dampening system meters an even 3-4 micron film of F.S. across the entire surface of the plate.

Run the press with the dampeners on the plate ................. IS THERE an even film of water (F.S) across

the entire plate - G.S. --- W.S. ?????


Regards, Alois

 

[Cornishpastythighs]

Check you have good flow of fountain solution in and out of your pans, if the issue is only on the gearside of every unit then I doubt chemistry is the culprit. Are you using some kind of RO treatment because 3000 conductivity seems high unless your raw water is high also.

 

[joe stag]

Raw water is 1000. I have not tried to set the system using the plate as an indicator. I will try that tonight. I do know for sure that all rollers are set to spec i have checked and rechecked to be certain nothing is coming out of setting. I am still learning this press with very limited training and i am not sure what speed range is normal for the dampening system. With the pan roller set to loss of heavy water plus a quarter turn on both sides and speed just high enough to clean the entire plate my black ink was water logged within 7000 sheets. This is why i was thinking chemistry. There is no window between the two. And spot colors are hypersensitive to any change in water speed. Give a little and it floods take any away and it is dry and spikes the density. Also we are cooling the ink train rollers to 66 degrees. I have never used a cooling system on the rollers and i am not sure what temp i should be starting with. Thank you for all your responses i feel like everything i have learned doesn't work.

 

[Cornishpastythighs]

With your raw water so high who knows whats in there. I would seriously talk your boss into some kind of water treatment for your fountain solution. Some press parameters are beyond your control but you should certainly control the ones you can

 

[joe stag]

What would cause only the areas that the paper does not extend to scum? Builds on blanket as well.

 

[aqazi81]

What would cause only the areas that the paper does not extend to scum? Builds on blanket as well.

If ink is water logged or chemistry issues, this will happen. Search this forum for Picture Framing and you will get your answer.

Inking roller temperature should be between 25-28 degrees Celsius.

Hope this helps.