Xerox J75 Solids on 300gsm Coated Stock

[Haunts]

Hello, i used to operate a KM C6000 so i'm new to the Xerox J75. Basically i'm trying to run a solid colour (PMS307) on to a 300gsm Silk but the solid is coming out very patchy. I've tried it on 300gsm Uncoated and its fine, i've tried on a 200gsm silk and its fine. I wasn't sure if anyone else has experienced this or if there was any settings people could suggest?

 

[arossetti]

Sounds like you need to adjust the 2nd bias.

Make sure the stock is in your library.
Login as admin
Go to machine status-> tools->paper tray settings->stock settings->

Select the stock in question and adjust the bias setting by percent to 70% and see what happens. If it gets better continue going down. If it gets worse try 130% and continue going higher until it is fixed.

I'm sure better info is in the system admin manual or you can ask further questions if you get stuck.

 

[Justin de Kruyf]

I've recently gotten a couple of humidifiers set up next to our digital printers and the difference has been huge on troublesome stocks like this.

Now if I'm getting patchy solids on 300gsm Silk I just sit the stack by the humidifiers on a cart, turning occasionally for even exposure, until I can see & feel the stock has regained its moisture and then my solids are awesome. As far as I can tell the moisture content is critical for the transfer to sheet. This has also been a massive help with linen and laid and some specialty pearlized.

I realise most of the users on this forum work in controlled environments but I certainly don't so this primitive method of soaking the stock is the best I can do so far.

 

[Haunts]

View attachment 3973

Sounds like you need to adjust the 2nd bias.

Make sure the stock is in your library.
Login as admin
Go to machine status-> tools->paper tray settings->stock settings->

Select the stock in question and adjust the bias setting by percent to 70% and see what happens. If it gets better continue going down. If it gets worse try 130% and continue going higher until it is fixed.

I'm sure better info is in the system admin manual or you can ask further questions if you get stuck.

The Admin Manual is poor, it doesn't really go into any detail on anything.

What is a bias? Also i can't seem to find it anywhere. I have posted a few screen shots below of my options in the paper tray settings and one of custom paper settings which has an option of image transfer. I did try this but it didn't make any difference really.

I'm not sure if your gonna be able to see the problem from the photo's below (taken with my phone), its difficult to get the light right.

You can probably see it better in this photo between the text.

 

[kdw75]

I have had the same problems on our C75 and never could get the problem fixed, except by changing to a smoother sheet. I am wondering if the "Adjust Image Transfer" setting is what they are referring to. Though in my case it didn't seem to improve anything.

 

[Justin de Kruyf]

Adjust Image Transfer is what you're looking for, and the method unfortunately is just to turn the number up and down to see if there's an improvement anywhere in the range. If you get a standard size sheet loaded you can print a set of sample patches from within that screen that may help to indicate at what setting you'll see the best results. Your mileage may vary.. I was using this before I tried introducing humidity and the humidity was a far better solution.

 

[arossetti]

Yes adjust image transfer is what I was referring to. You will have to play with it to find the percentage that works best. You might have to use this setting in conjunction with the other suggestions (different sheet/humidity).

We measure our temps and RH daily, the J75 likes to be around 45% RH and if you are using a coated sheet I don't know if smoothness will be the issue but you might find a sheet with better coating.

Also: Blue solids have always been an issue with us and digital printers. Large solids are a pain anyways but a large screen of blue solid is worse.

 

[kdw75]

Yes adjust image transfer is what I was referring to. You will have to play with it to find the percentage that works best. You might have to use this setting in conjunction with the other suggestions (different sheet/humidity).

We measure our temps and RH daily, the J75 likes to be around 45% RH and if you are using a coated sheet I don't know if smoothness will be the issue but you might find a sheet with better coating.

Also: Blue solids have always been an issue with us and digital printers. Large solids are a pain anyways but a large screen of blue solid is worse.

Blue and purple is exactly where my problems were showing up the other day. It was a slightly rough uncoated sheet. Our humidity was down around 28%.

 

[arossetti]

We have a dehumidifier but not a humidifier so we are dry in the winter also. Past few weeks we have been closer to 30-35%. It just doesn't feel right buying a humidifier in Florida.

 

[Justin de Kruyf]

We're lucky if we hit 15% in the winter here. I was surprised that these humidifiers could even affect a space as large as mine with bay doors opening every half hour.

 

[jotterpinky]

We've had the same problems on our J75...this problem has always existed it seems on their Low melt toner machines. We have the same problems on our Xerox 700's, blue's seem to be the worst. However from testing it seems as though the 700's have a lot less mottle than we are experiencing on our J75. We've tried adjusting the "image transfer" which does improve it but not to the extent that we think it's salable. If we adjust the image transfer on our 700's we can usually get it looking pretty good. Not so with the J75, we've tried "standard mode" vs "productivity mode", adjusted the image transfer percentages all over the place etc. but don't seem to be able to help it a whole lot. As far as I'm concerned the jury is still out on whether this machine was a good buy. I would almost rather have the 700i we replaced it with back.

I will try the humidity idea though as we've never done that.

Another note with regard to this issue is that if we adjust the "image transfer" setting up (e.g. 150%) we see a lot more "tail-edge flip" where we lose the image on the tail end of the sheet, turning the image transfer back to auto or changing it to gloss mottle mode usually helps this issue.

 

[Keith]

When I have patchy-ness in my blues, it's usually the cyan developer. I have a test sheet that has a thick strip of each color 100% that I print when I see my machine having issues. The cyan will be weak and blotchy and the three other colors are perfect. I make a service call and the tech comes in and sure enough, it's the cyan developer. Have you had the developer or developer housing looked at recently?

 

[Haunts]

After much testing and changing of the image transfer settings i've give up, admittedly it did get a bit better but not enough.