Acceptable dot gains for sheetfed UV

[G_Town]

What are people getting for dot gains when running UV and hybrid inks?

What are the most common reasons for excessive dot gain when running UV/hybrid.

Why does UV have more dot gain then conventional inks?

Finally what are the solutions when excessive dot gain is happening?

Not a pressman just trying to see what are the causes and resolutions.

Thanks

 

[rich apollo]

Re: Acceptable dot gains for sheetfed UV

I don't think that Hybrid/UV inks inherently have higher dot gains.

Do the Hybrid/UV inks you're working with have the same tack as your conventional inks?

Are you running the same screening? Same paper?

rich

 

[G_Town]

Re: Acceptable dot gains for sheetfed UV

Well that's kind of what I thought as at a previous employer we ran UV all the time and I don't recall any issues with printing too full.

That I don't know, I do know we would adjust tack at my previous job, I'll need to find that out.

Yes and yes.

We get MONSTER dot gains compared to conventional inks and I'm trying to pinpoint why that is.

 

[rich apollo]

Re: Acceptable dot gains for sheetfed UV

Yeah, it may be as simple as running a higher tack ink set. Downside of that is that you increase the chances for picking.

You have to change the blankets to run Hybrid/UV, so you might look at the differences in the surface and compressibility of your blankets.

rich

 

[janezl]

Re: Acceptable dot gains for sheetfed UV

UV ink dot gain is very dependent of ink itself. I had experience, where Arets graphics/Belgium ink was showing very high TVI, while UV ink from Sun Chemical was less than 5% away from ISO values.
Printing blanket might have impact as well...

Regards, Janez

 

[Gerhard]

Re: Acceptable dot gains for sheetfed UV

Dot Gain cannot be avoided but handled. It is related to many things from ink to paper. Also you need using the right blankets. Also the running speed is important. Maybe your printer was scared and run it too slow. The easiest way is to make a special profile for your UV ink but remember, the moment you change the ink, the blanket or the paper you might need doing it again.
Regards,
Gerhard

 

[dub]

Re: Acceptable dot gains for sheetfed UV

One major thing to look at is your rollers too. Most commonly when you run UV inks, your rollers will swell up causing the higher than expected dot gain when ink is transfered to the blankets. Basically a chemical reaction between the UV ink and the compound of the rubber in the rollers. If the press is being used to run both UV and conventional inks, you should look at Chameleon rollers, I believe that botcher sells them. They have a special compound of rubber that resists swelling when UV inks are used. Also you will want to check the diameter of the rollers you are using.. may want to go a bit smaller as well to accomodate for the swelling.

Good luck,
Dub

 

[oldmanprinter]

Re: Acceptable dot gains for sheetfed UV

h5. {color:#339966}If you are using flint inks you will notice dot gains, the worse in yellow, can be approx 30 over at the 50% dot, also diamond rollers are really a good. duel compound is excellent if running between convential and hybrid, inx or sun are far better inks with less dot gain, a good durometer of 25 for all ink forms will also help you. {color}