Spot overgloss

[cole]

in the near future we will be printing a duo tone job. The client specifies that he wants a spot overgloss printed over all his pics. Any suggestions to the best way for doing this? We have printed jobs in the past but find that the pics come out sandpapery because of the amount of spray powder used.

 

[duct maestro]

How long have you been in this game? You ask some random questions

 

[turbotom1052]

If your gloss varnishing and your images feel like sandpaper your either using too much powder or your using the wrong grain size powder. Typically an inline varnish printed over even a heavy coverage duotone image shouldnt require more than a 25 to 30 micron powder, unless your printing on heavy board or a non absorbant type of sheet like foil or plastic.
If you are running the correct powder and it still feels like sandpaper then you need to just cut down the amount you are running. A good test for knowing if your running too much powder would be to look at your first blanket when backing up. If your first blanket is covered with spray powder after backing up anything less than 2000 sheets your probably using way too much. The safest way to find your desired powder setting range is to just gradually cut down on the powder until you find the lowest safe level. Run small lifts racking if possible watching very closely for setoff. Once youve found the point were the ink sets off then just bring it up a bit. Be aware that many older powder units will not speed compensate. As the press runs faster the printed sheet has less time under the powdering nozzles. You must increase powder output as you increase press speed. Use caution when arriving at your settings and take notes of things like press speed, powder setting, ink coverage, stock running ect. All of these recomendations are based on the assumption that your powder unit is mechanically sound and maintained. Good luck finding your powder sweet spot.

 

[cole]

Thanks for your reply Turbo, this is the way we normally do it. What I am interested to find out is if anybody out there is doing it differently. Perhaps there are other products that can be utilised. This way takes way to long plus the potential for setoff. gas ghosting, etc is great as clients normally want it as glossy as possible.

 

[turbotom1052]

Thanks for your reply Turbo, this is the way we normally do it. What I am interested to find out is if anybody out there is doing it differently. Perhaps there are other products that can be utilised. This way takes way to long plus the potential for setoff. gas ghosting, etc is great as clients normally want it as glossy as possible.

sometimes clients want unreasonable things. any client that doesnt have a respect for the limitations of the process will someday wind up biting you. I feel its the responsibility of either the sales dept. or someone in management to educate clients as to them limitations. You can only run so much varnish on a sheet before you start running into problems. The proper ink film thickness on varnish is just as important as the ink film thickness of ink. if really high gloss is required my suggestion would be to print the job on a premium sheet with lots of holdout and with high gloss. Then use a high gloss varnish but dont run more than a normal ink film. You didnt mention what size powder you were using. tell me more about the press and the powder system and perhaps i can offer some on point suggestions

 

[cole]

The clients are informed, some of them are just unreasonable. We are running this job on a MQ sheet using a satin matt stock. We use 20 or 22 micron powder both are normally fine to use. Press is a Xl. No probs with spray unit. 130000 sheets multi sigs so you can see why I want this job done as efficiently as possible. I've heard about an aqueous that works in the ducts, what are your thoughts?

 

[Weaver]

Turbo is telling you the best way.
1. Check the build of your images see if its to much build for that type of paper or your densities are to high.
2.varnish will only have so much gloss .especially on matte paper.
3. I would get like a 27 micron powder.
4. start low on your powder using your make readies like a test load. If your makereadies don't offset then like if you used 800 to 1000 make readies and they are good the next load should be 2000 to 2500 and then check it , keep increasing as you go.
This is just some helpful hints.

 

[RGPW17100]

A printer with the capability to print aqueous would get a better result. Using a strike though matte varnish on everything but the picture then inline gloss aqueous would give you the desired look and feel. Without the aqueous you could try to dry hit the sheet after it dries but I doubt that would dislodge the grit from the varnish.

 

[turbotom1052]

ive used fountain coatings before and they can have pretty good results, but there is a learning curve to them. youd want to test them in your plant for a bit to get comfortable with them before running them in production. Much care needs to be used to avoid drying on the rollers. and until you get a feel for how much to use and all the other little tricks it can be dangerous. It helps big time to have hot air knives to aid in drying. Infared drying i feel helps a little but its the hot air that works best.

 

[cole]

I have been told that using this type of coating would be tricky so we"ll be on guard. Our presses are equipped with hot air knives. Please confirm if I would able to run this coating as a spot coating. I have been told that it is not possible.

 

[turbotom1052]

I myself have only used this coating as an overall coating but i dont see why you couldnt spot coat with it as long as your registration requirements arent really high. Cutting a blanket to spot coat anything with registration requirements can be pretty tough without some kind of CAD plotter and even then you wind up with edges that arent really that well defined. They do make poly style plates that can be mounted on the plate cylinder that would register better. If i remember correctly they were called Dycril . Youd probably want to research the coating manufacturer to see if spot coating through your press rollers are an option. Good luck with it!!!

 

[cole]

Good on ya turbo. I have inquired about plates and blankets(coating unit) and shall see where we end up.

 

[turbotom1052]

try doing a search for Nicoat ink train coating. I beleive these guys are the leaders in the field and im sure have come a long way since the days of Kentucky shine which was a nightmare imho

 

[madjock]

Why don't you just rack the job in small lifts of 500, this way you can keep the spray down, there is less potential for ghosting, and you can possibly carry a bit more varnish, I have lost count of the times I have had to spend days throwing racks in order to keep jobs with unfeasibly large amounts of ink and varnish from setting off!!
Also if the job is like sandpaper, you could always polish it afterwards??

 

[turbotom1052]

I have been told that using this type of coating would be tricky so we"ll be on guard. Our presses are equipped with hot air knives. Please confirm if I would able to run this coating as a spot coating. I have been told that it is not possible.

are you sure your press is equiped with hot air knives??? a drying system that incorporates hot air knives usually comes with a press equiped with a tower coater. If your press has a tower coater that would negate the need for an ink fountain applied coating.