Scott I agree with that idea for a possible approach, may I please ask, have you tried it and had success? I imagine there may be a little compensation of brightness needed (as with printing images to go in frames under glass) as the glass inevitable absorbs some luminance. I guess there is also a possibility of the inks behaving differently when going down onto white paint rather than straight onto glass. Best Regards, Neil Barstow Imaging & Colour Management Specialist http://www.colourmanagement.net On Fri, Aug 19, 2016 at 9:42 PM, Scott Martin <scott@on-sight.com> wrote:

One approach is the print on the front side of the plexi (which is really just printing white first then colors) for reflective calibration and profiling purposes and then print on the backside (colors then white). Some would go so far as to implement a minor lightening curve and others wouldn’t. Have you tried this?

Scott Martin www.on-sight.com

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On Aug 19, 2016, at 1:43 PM, Randy Norian <rg500delta@mac.com> wrote:

Good afternoon!

It’s quite likely that this has been covered before, however, I have to ask.

We are attempting to print high quality images on the back face of clear plexiglass, with a white ink layer behind the image.

The print engine in question is a Rastek H625 (by EFI) UV-cured inkjet.

While I can color manage paper prints with this device, the backside-plexiglass printing has me stymied. The images are extremely bright and overly-contrasty, to the point of being unacceptable, especially as companion pieces to other latex work we’re doing.

I thought I’d just characterize the output on the plexiglass, however my ES-2000 won’t read the swatches through the plexiglass, for whatever reason — it simply faults out. I’m using EFI color profiler suite 4.6.

Have any of you faced the same issue? Any advice on how to go about color managing this sort of printing?

I know I have to figure out how to read these swatches, but beyond that, are there any caveats for working with "back side of glass” printing?

Many thanks-

Randy Norian

Hi from England Scott, Thanks lots for letting me know about your experience, its very helpful. I did do a test with a Mutoh (flatbed adapted) printer and Topaz RIP which prints onto glass with special inks [it’s a weird fish, that RIP, lots of the manual is about how the manufacturer's "by eye" method is better than using ICC profiles]. In this case, the regular process is to print direct onto the back of the glass then paint over the ink with white. The final piece is viewed through the glass - so as a reflective object, not a trans. Plainly, it can't be read through the glass but your thin plexiglass idea is a real good one. Thanks for that. We did try a test of painting the glass white first then printing onto that white surface, with the idea to read the inks direct (not through the glass). Unfortunately, in this case, the appearance of ink on paint is quite significantly different to ink printed direct onto glass. Another thought was to have inks on the front surface (to be read direct with the spectro) and white paint on the back but that looks weird so I'm pretty sure it’s a fail. I am planning to try opaque white glass, just for the profile making - in the hope that the inks will take to that glass well and we can "see" the same as we’d see in the "normal backpainted white process". i.e. inks printed straight onto glass - with white backing. I'll let you know ';~} That "Oreo" printing idea sounds like a fabulous, I'm not surprised it succeeded in gaining clients. Thinking out the box, yep, that’s what we love isn't it. again many thanks Regards, Neil Barstow :: Apple Solutions Expert :: Colour Management Specialist www.colourmanagement.net On Wed, Dec 7, 2016 at 3:27 PM, Scott Martin <scott@on-sight.com> wrote:

I agree with that idea for a possible approach, may I please ask, have you tried it and had success?

Yes, I’ve been doing it that way for many years with perfect success.

I imagine there may be a little compensation of brightness needed (as with printing images to go in frames under glass) as the glass inevitable absorbs some luminance.

Exactly. I hate making manual curves but this is a perfect example where it makes sense. If the RIP you’re using let’s you do it, I’d recommend it.

I guess there is also a possibility of the inks behaving differently when going down onto white paint rather than straight onto glass.

No, not really - not with UV Curable.

Years ago, one of my clients claimed to invent ‘oreo’ printing where he would print UV colors on plexi, then white and then the colors again. This would make not only a double-sided reflective print but also a transmissive print with incredible DMax and saturation. He carved a nice niche and has done a whole bunch of special installations around the US with this, working closely with the designers and with me tweaking the calibration for different kinds of situations. These are the fun jobs, where people are thinking outside the box, care about making a high quality product and enthusiastically want to involve the color guy.

Scott Martin *www.on-sight.com <http://www.on-sight.com>*

Hi Scott I will find out what I can about the inks this is a Mutoh / Topaz tie up you buy the package I believe. Swansea is pretty cool you're right. I am guessing you didn't visit Wind (pronounced like you "wind" up a clock) Street of an evening though, it's a bit like Bourbon St in N'Awlins, maybe worse as in Wind Street it's the girls going crazy. thanks Regards, Neil Barstow :: Apple Solutions Expert :: Colour Management Specialist www.colourmanagement.net/ On Fri, Dec 9, 2016 at 2:55 PM, <scott@on-sight.com> wrote:

I did do a test with a Mutoh (flatbed adapted) printer and Topaz RIP which prints onto glass with special inks [it’s a weird fish, that RIP, lots of the manual is about how the manufacturer's "by eye" method is better than using ICC profiles].

Oh god, don’t get me started. I have a competitor nearby that similarly claims his calibration "by feel" is better than anyone’s measurement based calibration, lol.

In this case, the regular process is to print direct onto the back of the glass then paint over the ink with white. The final piece is viewed through the glass - so as a reflective object, not a trans.

I get it - that’s pretty common. I’ve seen people actually use this type of print as “transflective” - both as a reflective print during the day and transmissively at night.

We did try a test of painting the glass white first then printing onto that white surface, with the idea to read the inks direct (not through the glass). Unfortunately, in this case, the appearance of ink on paint is quite significantly different to ink printed direct onto glass.

That feels like a red flag right there. We’re talking about UV Curable inks right? Not Solvent or something else? Perhaps I misunderstood.

Another thought was to have inks on the front surface (to be read direct with the spectro) and white paint on the back but that looks weird so I'm pretty sure it’s a fail.

That should be exactly the same as printing with the same ink order on the back side of the glass, right?

I am planning to try opaque white glass, just for the profile making - in the hope that the inks will take to that glass well and we can "see" the same as we’d see in the "normal backpainted white process". i.e. inks printed straight onto glass - with white backing.

Right, or calibrate and profile on Sintra and use that setup on other materials. I’m starting to get the feeling that you’re not using UV Curable inks for this… From my experience, if you want to print on glass you’ve got to drop everything and go UV curable. Tell us more about these ‘special inks’.

p.s. I was just nearby you in Swansea Wales a few weeks ago - gorgeous!