Question Flat Bed Peeling Issues on Coro – Looking for Settings/Profile Advice

[CizreK]

I’ve been running a Xante X-55 Flatbed (Dual Head CMYK + White) for about 3 years. I recently overhauled the system myself, replacing the pumps to fix a back-drafting ink issue. Print quality is now excellent, but I’m fighting a major ink adhesion/peeling battle on Coroplast.

• Ink Adhesion: Prints look great and pass the "dry" scratch test. However, if the signs get wet or hit temperature swings (Southeast US humidity/heat), the ink peels right off. You can spit on it and in 2 minutes peel it off with the same scratch method.
• The Specifics: Major issues on 6mm Coro (Grimco), but curiously less frequent on 4mm. Full-coverage specialty brand colors are the worst offenders.
• Current Prep: Windex/Vinegar wipe down, dry rag, then paper towel. Print head height is <1mm. UV Lamps at 80%.
• Current Software/Settings: iQueue. Uni-directional. Traditionally used Photo Quality/Elegant Screens at -8% to -10% density to prevent cracking.

Testing & Troubleshooting so far: Since there is zero documentation online for the X-55, I’ve been self testing the settings:

1. Screening: Switched from Elegant to Standard Halftone (133 LPI).
2. LPI Tweaks: Tried dropping to 30-40 LPI. It seems to bite better, but the dot separation is visible and light-bleed is an issue.
3. Angles: Research led me to 15, 0, 75, 45 for CMYK angles.
4. Mode: Testing "Production Mode - Max Speed" at 1440 quality is best or Sign quality is ok but lays a bit thick.

The Constraints: I’m in a shop where I can't easily request new spend (Dyne pens or 2155 fluid are out for now), so I have to fix this via prep or iQueue settings.

Questions for the Floor:

1. Coro Prep: Is Windex/Vinegar actually hurting the "bite" on UV ink? Should I be using 91% ISO or something else?
2. The "6mm Mystery": Why would 6mm peel more than 4mm? Is it a heat-sink issue with the UV lamps?
3. iQueue Settings: For those using Xante/iQueue, what LPI and Screen combinations are you finding give the best adhesion for full-coverage blocks?
4. Lamps: Should I be cranking the lamps up more, I know that will that cause the ink to become too brittle and peel but just wondering.

Any tips or tricks from fellow flatbed users (especially those who have survived Xante ownership) would be life-saving.

This is my first post here - sorry if its a bit heavy. Just going thru some struggles right now. I just want to know how Signs365 gets their prints so evened out.

 

[White Haus]

I've never heard of anyone using windex and/or vinegar to prep substrates before.

Have you tried prepping w/ isopropyl alcohol + distilled water? That's what we use when prepping sheets for our Oce Arizona. (Spray rag/sheet, wipe w/ wet rag, buff w/ dry rag)

I would assume you're having less issues w/ 4mm due to it being corona-treated - the 6mm likely is not.

Have you always had these issues or did the they just start after your overhaul/

 

[Boudica]

Windex and vinegar are a new one for me as well.

 

[CizreK]

I've never heard of anyone using windex and/or vinegar to prep substrates before.

Have you tried prepping w/ isopropyl alcohol + distilled water? That's what we use when prepping sheets for our Oce Arizona. (Spray rag/sheet, wipe w/ wet rag, buff w/ dry rag)

I would assume you're having less issues w/ 4mm due to it being corona-treated - the 6mm likely is not.

Have you always had these issues or did the they just start after your overhaul/

I have not but am going to suggest it. I might only ever use Alcohol on Max Metal or AL materials. Do you ever have issues with the oils and debris clumping with Alcohol?

These issues were a big problem 2 years ago but that might of been caused by the back drafting of ink back into the dampers due to bad pumps. This machine is a manual pump system and if you research those they all are terrible. It still blows my mind that the only way to get ink to move through this machine is from 1 pump that pulls from the wells thru the heads and into the waste jar. You would think they would of made separate pumps for each section. Since then this has not been an issues until this big batch and it is always the same client who 'has' to have 6mm and a custom specialty color. Other signs have normal wear and tear within standard warranty time frames. Real estate agents love to beat the hell out of these signs. God knows what they do with them but sometimes they come back looking like they were dragged through a war zone.

 

[Gino]

Dealt with flatbed since 2009 and never heard of your concoction. We always used 91% alcohol and wiped until dry. NEVER let it air dry

 

[CizreK]

Dealt with flatbed since 2009 and never heard of your concoction. We always used 91% alcohol and wiped until dry. NEVER let it air dry

It's not a mix we do its "Windex - With Vinegar" from Windex themselves.

 

[signheremd]

Some coroplast has been treated for better adhesion (corona treatment I believe) and some has not. Coroplast gives off an small amount of oily excretion, likely more so on 6mm than 4mm, and this may be the core of your problem. Try cleaning with denatured alcohol or 90% isopropyl. For tough situations, we use Matthews Plastic Paint Prep (Grimco sells by the gallon) or Solv S1000 Plastic Prep (RPG Square Foot Solutions sells this). In any event, be sure to wipe in the directions of the flutes and not across them and include a dry wipe at the end - we use a microfiber cloth. You might also crank up the lamps a touch to improve adhesion

 

[White Haus]

Some coroplast has been treated for better adhesion (corona treatment I believe) and some has not. Coroplast gives off an small amount of oily excretion, likely more so on 6mm than 4mm, and this may be the core of your problem. Try cleaning with denatured alcohol or 90% isopropyl. For tough situations, we use Matthews Plastic Paint Prep (Grimco sells by the gallon) or Solv S1000 Plastic Prep (RPG Square Foot Solutions sells this). In any event, be sure to wipe in the directions of the flutes and not across them and include a dry wipe at the end - we use a microfiber cloth. You might also crank up the lamps a touch to improve adhesion

That Matthews stuff is great, we use it when printing to aluminum, acrylic etc.

 

[CizreK]

I am going to change to alcohol now to clean it now with everyone's responses and research. No one has touched on any settings tho. Even with proper cleaning if the machine is set to 'elegant' and 'photo quality' it lays so much ink down. What methods can be done to evenly spread the ink out where it cures nicely with no caking but also does not let light bleed through. The 6mm Coro we can grab does not come in opaque for us so messing with the LPI and all that seems to make it glow when back lit. Even tho Signs365 has a nice lay down of ink their signs also chip off. Had some do it today when unboxing them.

 

[Gino]

It's not a mix we do its "Windex - With Vinegar" from Windex themselves.

I meant using those ingredients, regardless of who made it

 

[ProColorGraphics]

I use this stuff, works good. the 2155.

UV Adhesion Promoters For Use With UV & LED Inkjet Flatbed Printers

Our UV adhesion promoters work with UV & LED curable inks when printing on plastics, metal, glass, acrylics, PVC, and other substrates depending on which bottle you purchase.

supply55.com

 

[FireSprint.com]

First, try printing without wiping the board with anything.

Then try wiping down with 91% isopropyl alcohol using an L30 wipe from Kimberly clark.

If that doesn’t work, look up Kolorcure glass adhesion promoter.

While you’re doing that, get yourself a dyne test kit and educate yourself on how to use it. You probably won’t get good adhesion below about 36 dyne level. About 45 is ideal. If the dyne level is too low, get yourself plastic from a different supplier. Dyne level drops as sheets sit, so old sheets are harder to print on.

This has nothing to do with your sheets being 6mm vs 4mm other than 4mm is about 100x more popular than 6mm, so your 6mm is probably old.

 

[TEN]

If cleaning alone does not give enough ink adhesion you may need to use an adhesion promoter such as:

55UVAP3155L - AP3155 Adhesion Promoter - Wensco Sign Supply

55UVAP3155L

www.wensco.com

 

[bdw99]

Can also see if your printer has an "after cure" function.. Basically makes the lamps go over the print again after printing is finished. I have found it helps in certain scenarios. Don't know if it'll help at all in your situation but its one click so can't hurt.

 

[Jims209]

Are you laying down white under the print or on the whole board?

 

[CizreK]

So no one on this thread has any issues when printing from a flat bed to any coro - dunking it in water - and two minutes later being able to easily scratch it off? - Because once it dries its fine again. This seems to be the main issue with the prints we do. Once they get wet from rain, mist, dew, and are currently wet - they peel. Otherwise the ink is strong and bonded.

 

[Boudica]

So no one on this thread has any issues when printing from a flat bed to any coro - dunking it in water - and two minutes later being able to easily scratch it off? - Because once it dries its fine again. This seems to be the main issue with the prints we do. Once they get wet from rain, mist, dew, and are currently wet - they peel. Otherwise the ink is strong and bonded.

not here. Once I had some ink peel off of coro, but it was a fluke.

 

[CizreK]

Are you laying down white under the print or on the whole board?

No. I have only ever done that for a person who wanted a giant 54x48in ultra board print that was being hung indoors. The white helped get rid of any imperfections in the ultraboard. If we were to underbase coro with white I am pretty sure the ink would crack or peel even faster due to being caked up.

 

[CizreK]

It is all driving us crazy here. All the tests with changing settings, how you clean it, speeds, etc don't matter because they all fail when wet.

 

[Boudica]

It is all driving us crazy here. All the tests with changing settings, how you clean it, speeds, etc don't matter because they all fail when wet.

maybe it's not the coro.... maybe it's the ink? If it's so vulnerable to getting wet, it sounds like it's water soluble somehow. Ink, or lamps and curing properly.