Speckled print on Konica C3070

[gazfocus]

Just wondering if anyone can offer any advice on what may be causing this and how I can fix it? This is on a Konica C3070 and only seems to be affecting colours with cyan in.

 

[Digi_Wiz]

I'd try to adjust your transfer settings and weight. +15 transfer is a good place to start if it continues that way its likely the quality of the paper of you will need to have a technician come to make sure your drums and developer are within lifespan.

 

[gazfocus]

I'd try to adjust your transfer settings and weight. +15 transfer is a good place to start if it continues that way its likely the quality of the paper of you will need to have a technician come to make sure your drums and developer are within lifespan.

Ended up having a tech out. He was here for a few hours, tried replacing a part (something he didn’t have on him so had to get from another tech) and that didn’t solve it.

He then tried printing the same document on his own stock and that printed perfect (although was a much thinner stock), put my 350gsm back in and same problem.

He went away not knowing what the issue was. He said all drums etc are well within their lifespan but he’s ordered a PM kit which will take about a week to arrive.

Funny bit is, came in this morning, tried printing the same document again and it printed 100% perfect.

We have also used the same stock from the same batch a week ago, printing the same document and it was fine a week ago.

 

[jwheeler]

Funny bit is, came in this morning, tried printing the same document again and it printed 100% perfect.

We have also used the same stock from the same batch a week ago, printing the same document and it was fine a week ago.

Is it possible that the paper has a different texture/finishing on one side than the other? Or just more pronounced? I'm wondering if you may be putting the paper in different sides up each time which is why it only works sometimes.

 

[PricelineNegotiator]

Maybe a humidity issue? It looks like the second BTR or developer is causing the issue if it is not the humidity.

 

[pippip]

Have you checked the stock under a loupe? I think I had similar years ago and it turned out to be dodgy 350gsm card. Under a loupe you could actually see the divets. Can you order another brand of same stock?

 

[phoenixrje]

Paper does have a different finish from side to side. My experience running a KM C1060 was that uncoated, textured stock was difficult to get the toner to lay down nicely and fill the texture of the paper. The newer machines have a softer transfer belt that helps with this issue.

 

[gazfocus]

Is it possible that the paper has a different texture/finishing on one side than the other? Or just more pronounced? I'm wondering if you may be putting the paper in different sides up each time which is why it only works sometimes.

Not that I can see. We often do double sided with the same stock and don’t have any issues (not to say it’s not possible though).

 

[gazfocus]

Maybe a humidity issue? It looks like the second BTR or developer is causing the issue if it is not the humidity.

According to the tech, the humidity reading on the machine was fine. I’m wondering whether the machine just didn’t warm up properly as we’ve had issues with it not warming up in the past but it usually just throws a ‘call service’ message.

 

[gazfocus]

Have you checked the stock under a loupe? I think I had similar years ago and it turned out to be dodgy 350gsm card. Under a loupe you could actually see the divets. Can you order another brand of same stock?

I’ve not no. As I say the tech brought his own stock but was about 130gsm vs my 350gsm and his worked fine. It seems to be working ok at the moment so will give KM a call on Monday to cancel the PM kit.

 

[Ynot_UK]

I’m wondering whether the machine just didn’t warm up properly as we’ve had issues with it not warming up in the past but it usually just throws a ‘call service’ message.

I’ve seen something similar once on our C4080, on heavy solid coverage immediately after powering up one morning.

 

[farcrowd]

It's a paper humidity issue. I just replied to this exact same issue on another forum. I've run into it on a variety of stocks before. It has nothing to do with the press humidity, it has everything to do with the climate where the paper is stored.

As an example, here's our most recent encounter with this issue: We occasionally print on Mohawk Ultra Gloss C1S 10pt. As we don't run it much, we've had a partial ream open for a while now. I ended up getting a job that would use this stock, so I ordered a couple more reams. I wanted to run the open stock first, but the first print showed this exact same speckling/mottling issue. We opened up a new ream and voila...beautiful prints. So what changed if we had been running the open ream just fine until now? A while back I moved the open ream from our pressroom to our bulk storage area where the climate is a bit different - it's more of a warehouse area, whereas our pressroom is more of an office area with better climate control.

99% of the time, when I pull paper from our bulk storage area and immediately run it - there are no problems...but occasionally there is a paper that shows this issue. It's either an open ream or a partial bulk carton - both of which we haven't run for a little while.

I have seen this issue on our previous Konica C1060 and our current C3080. I usually just run from a different box/ream if I see this issue, and then bring the affected papers into our pressroom to acclimate over a few days.