Help with HP 700 latex

[Alpha Star]

I’m hoping someone with this printer can help me interpret this.

I’m about to purchase the printer, but I noticed something alarming about three test prints I received.

All passed the initial scratch test we do (we don’t want to laminate).

On a random whim, I decided to test them again after exposing them to a humid environment, and two of the three instantly lost their scratch resistance! Oracal 651 and a polypropylene. These were the materials I supplied, and ink just rubs off when slightly humid. The third one was a chrome stock called Aslan that they provided, and it passed the humidity test with no trouble.

I would not be able to use this printer if this is the normal output. Is it just a question of slowing it down or raising the heat? Does anyone know about the humidity problem? I waited a month for the last sample, so I really just want advice from an experienced user.

 

[ikarasu]

When you did the print...did you have the overcoat turned on? Most medias turn it off presuming you will be laminating (At least all the medias we use have it turned off). we found it pretty scratchable unless we turn the overcoat on

 

[Alpha Star]

Oh, okay. I saw a Lexjet video that said it was on by default. I can’t be sure because it was done by someone who did not speak to us directly, but so think it was on because it’s quite scratch resistant until you breathe on it directly. That little bit of humidity makes it garbage.

 

[ikarasu]

Its really scratch proof, humidity or not - We do tons of stuff unlaminted and it stays up for years.

651 is a non printable vinyl - That could be what your issue is... I've never personally tried to print on it, but it isn't Latex / solvent compatible, just thermal.

I'd supply them with some Latex media and test.

It may be on by default, but it depends on the profile. I dont remember changing all ours to off - but using 180 profile for example, its turned off - I imagine its default off because 99% of the time when you're printing on expensive material, you laminate it. I'm not 100% sure though as I'm not too involved in the profiles anymore - I just know we never have any scratch issues... so it's either a media, or profile issue

 

[Alpha Star]

Thank you! Yes, I could easily switch to a printable vinyl, but the polypropylene is what it is and I can’t switch it. Is the heat level and print speed likely to be a large factor?

 

[ikarasu]

You could try turning up the optimizer, optimizer is what bonds the print to the material. If the material sits for a day or so, it also becomes more scratch resistant... I have a light cloth material I print on, its pretty scratchable fresh off the printer - but once it sits for 2 days you cant scratch it at all.

What brand / model # is the polypropylene? and what do you use it for? It's used for quite a few things, so hard to say if theres a Latex version or not.

 

[balstestrat]

You could try turning up the optimizer, optimizer is what bonds the print to the material.

No it doesn't. The main function is to keep ink in place until dried and cured. It shouldn't matter if you set it to 0.

 

[ikarasu]

No it doesn't. The main function is to keep ink in place until dried and cured. It shouldn't matter if you set it to 0.

I stand corrected... I could have sworn our rep told us it was like a primer and it allows the ink to bond to the material better, so stuff that flakes off / scratches easy you should increase optomizer and it'll help it bond better.


https://lkc.hp.com/forum/printers/re-latex-300-series-improving-scratch-resistance - How come all the HP reps seem to tell you to increase optomizer to increase scratch resistance then? This is just one example, theres probably dozens out there... I'm guessing level 1 support who dont understand what theyre saying?

Not doubting you, I watched the official HP video and it mirrors what youre saying - it's just funny the HP Forums are filled with reps telling people to increase optomizer to help bond to material better.

 

[balstestrat]

I don't know, some misunderstanding or whatever. But I don't remember anyone from HP recommending me to increase OP for adhesion.
However I can't say if it has some small effect or not. Anyway the more you put it the more you need to cure it as OP sits at the bottom.

 

[Alpha Star]

Wait… my prints are great until exposed to humidity. Is it possible for optimizer to shield the ink from humidity?

 

[Christian @ 2CT Media]

Wait… my prints are great until exposed to humidity. Is it possible for optimizer to shield the ink from humidity?

You need to make sure overcoat is on and the levels adjusted. Polypropylene has a very smooth surface unless it's textured which leads to ink adhesion issues. You are running tests with no control of the machine, you will never get a solid answer, but you have to verify that they were using overcoat.

 

[Splash0321]

I’ve not printed on 651 with my 700w but I have used 751 and 951 with great success. I have also printed on 3m scotchcal 50 series quite a bit with no issues. I’m based in Florida, plenty of humidity here and I’ve had no complaints of fading or scratches with unlaminated prints.

It sounds like a curing problem and/or no overcoat being used.