Web Heatset Voids in Print - Please Help!

[D Ink Man]

Chasing a problem on a high speed Lithoman IV. At higher speeds the Black will start to print unevenly. Strange, it seems to happen only in small solid subject areas. Text type, 10 pt will print fine and then 48 pt Bold type will be distorted. Have run the gamut of changing inks. More water pick up, less water pick up, more lubrication, more stability, no help. Happens at higer speeds; 30,000 x 2, over 2200 feet per minute. Slowing the press down, alliviates and helps the solid black return to continuity. Have used 2 Fogra type fountain solutions at 4.5 - 5.0 and also normal acid solution at 3.8 - 4.2. Conductivity normally 2000 uhmo. Use FUJI LH-PJ plates and Day 3610 blankets. Happens on 70# Gloss and also some lesser weigt sheets. 45# Escanaba usually runs OK. Automatic blanket washers, using a Green Varn product. Halftones OK, text type, all oK. Small solids black again the problem. Sometimes magenta, but may be different problem. Only occurs about 15% of total press running time. Don't think it is an ink problem. Looking for suggestions. Help!!!!!!!!!!

 

[gordo]

It might help if we could see the problem. Would it be possible for you to scan a section of the press sheet that shows the problem as well as the same section that's normal? If you scan at high res it's like using a microscope. Even a cheap scanner will do a good job. Use a black backing to prevent show through. Here's a sample of 8 pt type scanned at 4800 dpi:

best, gordon p
my print blog here: Quality In Print

 

[D Ink Man]

Gordo, thank you. I will try to arrange to have some examples sent. Thank you for your concern and help.

 

[rich apollo]

Please do. I've been chasing a similar sounding problem.

 

[Darlek]

Web Heatset Voids in Print - Please Help!

Being a speed related problem it can only be roller settings. Rollers thro off in their centre a suprising amount at speed. Try firmer settings or new rollers. Rollers also loose there sure hardness over time and when this happens you can get worn plates & problems with solid areas at speed. If no new rollers are available try a good Varn Paste with spirit then hot water. If it is not this then it be a big problem such as cylinder bearings. Although noise should be apparent if this is the fault.

 

[D Ink Man]

Gordo, I have some signatures and examples of the problem. If you could give me contact information, I can send them to you. Thank you.

 

[D Ink Man]

Please check attachment.

 

[D Ink Man]

Keep in mind, the pattern shown in the attachment is not always the same. Sometimes just rounded, snowy like print. Thanks.

 

[D Ink Man]

Has anyone seen the attachment above for appraisal?

 

[Robilious]

Just a suggestion, try a different Blanket. May be a release problem? Wanna stay in the Day family, try Day 3700's.

 

[Robilious]

incidentally, every fountain solution product has a specific conductivity, per oz, per gallon. So, 2000 doesnt mean so much if the fount is to be mixed 3 oz/gal and the conductivity is 450 micromhos per oz and water is R.O?