micro vertical lines and dots with gloss paper(I forget to upload original pics in the previous two posts, this is the correct one)

General
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1

Hi walker are you there? Come in and help me please!

I transformed a scp808 recently and everything went well until I try to print on the HAH-photo rag baryta 315. There are some micro vertical lines that I could never eliminate. I post two pictures(pic.1/2) so you can check the details of it.

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I tried everything I could, including head cleaning. heavy cleaning, gap setting or so. Sometime I just left the printer there until next day and hoped the lines will gone automatically by time. But those micro barnacles never went away.

There were several times when I seemed to have alleviate those lines( I couldn’t remember how, maybe by gap adjustment), then followed some micro white dots(pic.3) which could be eliminate by “ stop printing and wait for 12 hours”.

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By the way, the micro lines are mostly obvious in the mid-tone area while micro white dots are mostly obvious in the shadow area.

Both micro barnacles couldn’t be washed away by ink.

and here are some more details of our machine and software setting:

we are using a scp808(China version)and it is a brand new one that has never be installed with epson inks.

we didn’t test the machine with epson inks, we just load it with 9 flush cartridges and made several heavy washing. The test result is just great, so then we load our P808 with the ink set. Our ink set is shown in pic.4. It is a k7 set with selenium.

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Then we installed the quadHDK6-P800 printer and the HDK6 curves from your official website. These settings can be viewed in pic.5.

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Firstly we print on HAH-photo-rag308, it was just fine, no dots and micro lines at all, maybe because it is a matte paper so ink drops can to some extent diffuse away to cover some flaw. I am not sure.

Because there is no default curves for p800 with HAH photo rag baryta, I choosed the “k6-HDPK-sel-hah photorag pearl”. The other printing settings are in pic.6.

Do you have any ideas to resolve the micro barnacles?

if so please do help me or I will be kicked by my boss.

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2

Try printing this with rear feed not front feed. I think your platen gap is too high!

-Walker

3

Thank you Walker, but the scp808 doesn’t support a rear feed, maybe I can try the auto feeder?(the front feed allows paper thicknesses between 0.29-0.70mm, and the auto feeder allows 0.08-0.3mm, the thickness of hah-photoragBaryta is 0.43mm)
And by the way I just found that the micro white dots are the result of the paper coating. It seemed that our recent batch of Hahnemühle photorag baryta has something wrong with its coating. I changed to another batch of baryta and there are no white dots any longer. But the lines are still there.