Printing on Poly prop.............

[pipinfort]

Any tips for printing conventional 4 colour litho on poly prop.......can it be done successfully?. we have a set of tuftex inks to use which are apparently very hard drying oxydizing inks.....any other tips appreciated..

[Albert Noel]

use the thinnest ink film possible that still gives you pleasing colour.
also, run fountain solutions as low as possible, as any excess will not absorb into the substrate. if you have assisted drying, use it to get any excess moisture to evap, though dont go too hot. and if you have a coater (with a forced air dryer) try and get as much air flow to the sheet as possible but again,not too hot. rack it in small lifts and if you need to use spray powder, do so but not too much.
also, make sure you are using a hard dry ink.
this may not be the same as what everyone else does, but this has given me the best luck.

also, allow for plenty of dry time before backing up. or post processing. it will mark/scuff easily if not fully dry.

Any tips for printing conventional 4 colour litho on poly prop.......can it be done successfully?. we have a set of tuftex inks to use which are apparently very hard drying oxydizing inks.....any other tips appreciated..

[pipinfort]

Cheers, thanx very much................

[rbailleu]

we use an ink additive called speedy dry. depending on the poly's coating you may have to rack. I have had some poly that took 4 days to dry in small stacks. you may need something more than tuff tex call your ink company.

[D Ink Man]

The tuftex, (Van Son?) are very aggressive, hard drying inks and should do a good job for you. I am not a proponet of the Speedy Dry additive as it can have an adverse effect and actually slow down your drying. The label instructions on the SD, say you can add upwards to 20%. Trust me, that is entirely too much and will inhibit your drying at that level. Leave the printing to the printer and the ink that goes in your fountain to D Ink Man. Other tips: Short racked stacks, larger size spray powder (45-55 micron silicone treated) and reduce the amount slightly if you normally run a 30-36 micron size, wind the sheets carefully and allow ideally a recommended 48 hours before any necessary back up. Grafo (water activated drier) is the only ink additive I would recommend be added if you must at a 3% level. I would only add this on your most difficult synthetics and heavier coverages. Minimize your ink and water films to the barest thicknesses is of ultra importance.

[Asures]

I would first and foremost check the "Dyne Level." Many times, printers encounter adhesion issues and they are confused with drying. Ask your ink / stock supplier to furnish you with that information. Ideally, you want the dyne to be 38 or above. That is considered litho-suitable. *However, I have some customers that gamble with 35 or 36.

Appropriate Inks: You definately want to use an ink that is of an oxidizing formula formual used specifically for plastics or non-porous substrates (Vinyl, Static Cling, Yupo, Transilwrap). If you are going to aqueous coat, make sure that the coating is formulated for synthetic / non-porpous stocks.

Appropriate Fountain Solution: Try to reduce the alcohol replacement in your fountain solution mix. Fountain solutions / Alcohol Replacement diluted mixes that contain great amounts of wetting agents can actually retard the natural oxidation process from occuring. To assist, you can use good 'ol Hydrogen Peroxide purchased from over the counter. I would add 3oz. per gallon to your fountain solution mix and that will certain assist while creating a massive explosion of oxygen within the emulsified ink film transferred to the sheet.

Appropriate Powder: As mentioned by D Ink Man, try to use an offset powder for board. The heavier the micron, the less powder you can use. At the same time, you will have less direct contact with the wet ink film and the backside of the sheet.

Small Lifts: Depending on the thickness of the stock, run small lifts. The heavier the stock, the greater a chance to offset that job baed on the ink coverage and 4/c solid areas if any.

If the job is a work and turn or work and tumble, try to run the heaters as low as possible to avoid any fit issues when printing the backside.

Hope the advice helps.

Best Regards,

[D Ink Man]

Asures,

That is an interesting one about the Hydrogen Peroxide. Never had that before, but sounds like a good tip. Is there any draw back at all with this chemical?
Thanks.

[meddington]

No experience with it here, but hydrogen peroxide is rather reactive. I'm wondering if this would have an effect on the permanence of printed material or perhaps corrosion of the water system (copper/chrome) in any way? Usually see this used as a bleaching or de-inking agent.

[Asures]

Guys,

I am referring to Hydrogen Peroxide that you would have in your medicine cabinate or pantry. It comes in the brown, plastic bottle. This stuff isn't used for bleaching.

Here's the analogy: If any of you guys have been around children (kids or family) and they suddenly fall.. After rthey get up, you notice that they have scraped their elbow. You brush all the debris off and then apply peroxide to the wound. Immediately after doing that, the scrape starts to bubble and the blood starts to clot forming a scap.

What's happened to the blood here?? It's Oxidized..

Same principle in printing. The pH is neutral of Hydrogen peroxide. Really, it's simply oxygenated water that you're adding to the fount. When the emulsification process occurs, you can be assured that all layers of ink film are going through this "Forced Oxygenation" and all layers will dry parralel. I have seen remarkable, reduced dry times as a result.

I have assisted some customers on extremely long runs, running triple hits of opaque white on gold metallized stock. My clients have had no issues with corrosion using this process. Again, they are only adding the Hydrogen Peroxide at the time of running plastics / non porous substrates.

Best Regards,

[meddington]

I am referring to Hydrogen Peroxide that you would have in your medicine cabinate or pantry. It comes in the brown, plastic bottle. This stuff isn't used for bleaching.

Sure it is. My sister used to use it on her hair. Point taken though that the concentration is likely much lower in the off the shelf variety...though that one guy was just arrested for planning to build a bomb using H2O2 from beauty supply stores.

Same principle in printing. The pH is neutral of Hydrogen peroxide. Really, it's simply oxygenated water that you're adding to the fount. When the emulsification process occurs, you can be assured that all layers of ink film are going through this "Forced Oxygenation" and all layers will dry parralel. I have seen remarkable, reduced dry times as a result.

Very interesting. We're currently looking into printing offset on Tyvek and I'll have to look into this further.