Powder system

[Kaoticor]

A question to my fellow sheetfed operators out there:

Does your powder system have a noticeable effect on your sheets?

Our powder unit does not appear to have much impact on the process, and never has. Currently, whether we run it 100% or 10%, there seems to be little to no difference. We are loking to improve the dry time between our ink to substrate, and this unit came up. My question to you, is do you see significantly improved dry times or set-off protection with your powder unit. If you were to run your powder unit 100% on an UWF sheet with heavy ink coverage, no AQ, and using IR, would you be confident there would be no setting off of the sheets? Thanks for any information you can provide,

-K

 

[Cornishpastythighs]

Have your powder unit serviced to ensure it is not clogged up with crap, make sure you are using the correct micron size and have your IR dryers checked also. Spray powder never made any difference to our dry time but with a properly functioning IR system and spray system that is putting out correct amount of powder you can achieve no offset with heavy coverage. Make sure your inks are of enough strength so as to not carry a thick ink film to achieve density.

 

[Lukew]

Our spray powder unit is super sensitive, even though there is a dial from 0 - 5 or something like that and a total movement of 100mm. You can only run it between 1 - 1.5 "light coverage - heavy coverage board" The difference for jobs on 130gsm gloss/matt stocks to be run through the machine again have the dial set on 1. If its under or over that by a 2mm movement of the dial, it will either set off or over powder the sheet.. Drives you crazy.
Guess its just another poorly designed shinohara part.

Regarding setting & final drying of the ink, according to the ink manufacture if it is mineral oil free ink set, the IR drier has little effect & can actually cause blocking.
Secondly, as its been said many many times before, check the total glycol content of the fountain solution. This has a big impact on the inks ability to set/final dry.