Washed out colors with illuminated lightboxes

[ColorCrest]

Being aware or familiar with the previous state-of-the-art of how backlit display graphics were produced beginning decades ago may help provide some insight or aims to construct a good product that one might produce with current inkjet technology.

To this day many backlit products are often referred to as Duratrans. The term is a brand name invented and trademarked by Kodak, the photo company. Duratrans, Duraclear, and Day/Night use a common color photo exposure and developing process but with specialized settings compared to traditional color photo prints. Fujitrans and Fujiclear was another option and I don’t if Day/Night was offered by FujiFilm, Inc.

The media is a 7-mil translucent polyester film coated with a light-sensitive emulsion for the trans and clear versions and the day/night media is coated on both sides of the film. Duratrans has a milky-white translucent base and requires no other diffusion when installed in a good light box. Duraclear is practically optically clear and has no built in diffusion. Day/Night is translucent white but the white is especially bright due to added optical brighteners to optimize the “day” side appearance. Because the Day/Night film is coated both front and rear, the photo exposure occurs in one pass making production very efficient with perfect image registration front to back. Essentially a color/white/color technique with the white composed of a very unique and patented construct.

Being that these products are photographic, they are continuous tone with no dots. A Duratrans print will appear very dark until illuminated from the rear. A Duraclear print can be exposed to any optimum degree necessary for its use, front or backlit. A Day/Night print appears only slightly dark until properly illuminated for both front side and back side. The polyester film is somewhat stiff making for slip-in installation and shipping in mailing tubes easy. The film is also dimensionally stable and does not stretch.

Due to the current nature of the industry and the flux of supply chains, I can’t imagine the photo options easy to find these days. However, the current state-of-the-art uses very similar media (always polyester film) only coated for ink reception and affords the benefit of being practically waterproof where the photo prints are not. Most backlits happen to be printed using aqueous, high color gamut ink sets nowadays. A downside is Day/Night requires more printing using various layering methods making for a more expensive product than the past.

I'm not sure if the OP ever specifically asked about about a day / night product but some background still might be of interest to forum visitors.

 

[Magman]

You need to understand the physics of what happens when you look at a sign. If the sign is viewed by reflected light, i.e. sunlight, the light passes through the ink twice, since the ink is transparent. It goes through the ink on the way to the white substrate, and then again after it bounces off the substrate and comes back to your eye. You take that same printed vinyl and light it from behind and the light only travels through the ink once, leading to the print looking washed out because the color density is halved.

If you try to compensate for this by printing double strike and having greater density of ink, you may achieve an improvement when backlit because you have more ink density, but the print will be too dark and oversaturated with altered contrast when frontlit because the light, again, is passing through the ink twice.

That's why the ONLY way to achieve a sign that looks good both front and back lit is to have color/white/color on the vinyl. There are a couple of ways to achieve this. If you have a printer with white ink capability, you can do it in the printer/RIP so it prints that way. This works well with UV printers and I've bought some great direct-printed faces done this way. I haven't been able to achieve as good a result with roll fed solvent printers, most likely because the white ink isn't dense enough and the solvent inks tend to mix with the layers below.

The method that has become my standard is to layer the vinyl. We print the same regular print on clear vinyl and on translucent white vinyl, which we laminate for UV protection. If you have calibrated your printer for each material so they print dimensionally correctly, it's a simple matter to mount the clear print on your substrate, then mount the white print on top of it. This achieves as close to perfect color in both front and back light as I have seen anywhere.

Thank you going to give this a try.

 

[Gino]

I have several duratrans here in our shop. They're old, but like you said, very good quality. However, I don't recall our request or have seen any used outdoors. Can they even be used outdoors ?? Never confused using the term duratrans with a backlit sign, because backlit signs are generally for outdoor use for about the last 80 or 90 years. The duratrans only came into use in the 80s and we called them endurotrans, I think. They were still backlit, but for interior use only. Comparing the two methods is not really kosher, as it was used and made possible two completely different ways and for different applications. One is printed, while the other is like photographically produced with chemicals and exposure times, much like a regular old photograph.

 

[Bobby H]

Standard 27" X 41" movie poster "one sheets" are typically printed on both sides of the sheet. The artwork doesn't wash out when back-lit in a lighted movie poster case.

 

[ColorCrest]

Comparing the two methods is not really kosher, as it was used and made possible two completely different ways and for different applications. One is printed, while the other is like photographically produced with chemicals and exposure times, much like a regular old photograph.

Understood Gino, and yes, a genuine Duratrans™ is the regular old photograph except using a strong film with modified coatings and exposure along with modified development times sometimes. However, it's a photographic print never the less and it used to be the go-to method for certain signs before inkjet technology.

And yes, the OP did not describe their graphic design or its application. They just wanted to learn how to avoid the color from washing out. I was hoping those interested could glean from my post and from what others have already mentioned about some basic principles; backlits require heavy color and a diffuser somewhere in the mix when it's necessary.

There are still plenty of advertising agency staff who still use the term "dura" for any backlit sign display they order. "Dura" still means certain types of displays to them and their customers especially in regards to graphics for mall directories, airport ads, trade show and retails displays, etc., including outdoor light boxes. They don't really know them from brand or materials or production machines.

 

[ColorCrest]

Standard 27" X 41" movie poster "one sheets" are typically printed on both sides of the sheet. The artwork doesn't wash out when back-lit in a lighted movie poster case.

Only if the graphic was to be a day / night application would it be necessary to print both sides.

 

[bigben]

We just did a series of tests to find the best compromise and the winning result is a sandwich print with the white at 75%.
We print on an HP 800W.

I have the 700w. I will try that next time. I've never thought of the 3 layers print for this application.

 

[BRated]

We just did a series of tests to find the best compromise and the winning result is a sandwich print with the white at 75%.
We print on an HP 800W.

What are your passes like what kind of mode are you running? I saw a video once where they dull the lower layer then white then top is Normal do you do anything like that?

 

[Texas_Signmaker]

Don't double strike your print, that will never look good. Too dark during the day and washed out at night. You have to do color white color. If you don't have the capability, sub it out. Indy imaging is a good company for that.

 

[RabidOne]

What are your passes like what kind of mode are you running? I saw a video once where they dull the lower layer then white then top is Normal do you do anything like that?

Before I got here they would oversaturate a single colour print. We tested a bunch of different options and the best option was Sandwich reducing the white to 75%.
Allows some of the first colour layer through but doesn't get washed out when the lights are on. Its a seriously slow process: something like 70 pass at 600 dpi, but thats because its printing 2 colour layers and a layer of white. Max I am printing one of those a week so the uber slow print time isn't killing us.... yet.

 

[Action Mary]

I printed three 6" samples of a multi coloured graphic on clear vinyl. 1 pass, 2 passes and 3 passes. I then put them all on a thin piece of clear Lexan. I show that to my customer to show them the differences and ask them which do they want. I have it on clear so I can put it on different pieces (sign white - max metal, coroplast, etc). If it is going on an illuminated box, I put it on some white lexan and then a flashlight behind so they see, it will look different.

 

[BRated]

Before I got here they would oversaturate a single colour print. We tested a bunch of different options and the best option was Sandwich reducing the white to 75%.
Allows some of the first colour layer through but doesn't get washed out when the lights are on. Its a seriously slow process: something like 70 pass at 600 dpi, but thats because its printing 2 colour layers and a layer of white. Max I am printing one of those a week so the uber slow print time isn't killing us.... yet.

Thank you for this, I'm recently testing contravision in reverse on the inside of a window so laters of colour then white then black sandwiched and wondered if I can speed up the process but the sandwich passes on default are like 40 passes for the quickest default set.

 

[GraphixGirl79]

Okay, if this has been asked and addressed before I apologize.

I build a lightbox with a white polycarb UV coated panel. My digitial print is printed on a translucent printable vinyl. When not illuminated it is spot on beautiful. When I light it up. the colors are all washed out.

So I'm wondering how we keep the print vibrant when illuminated? I've attempted high pass Icc profiles-- help a little but not much... Does this occur due to the diffusing properties of polycarb and or acrylic? If so would adding Avery 30 or 60% diffusing vinyl on the inside?

I've printed on both Eco solvent translucent and my UV and both look ugly washed out once illuminated. What is the best way to get excellent results here with illuminated translucent vinyl , or should I print clear?

When looking at backlit films that looks awesome illuminated....???

I find that i get the results i want when i do a 2 overprint method. before i send it to RIP i adjust the colors to between 85% and 80% or the originals so that the colors don't come out TOO dark when you're running a 2 overpass. We generally use a clear print media for illuminated sign box/face options, it is more vibrant and looks better in my opinion than a translucent white media. The colors will be a "little" darker than if you're running one pass during the day view, but it's usually not too different that the customer would notice. And if they are a more reserved customer, and "choosey"... lets not say the P word here, you can always offer to run them a sample print before production. I'm sure you could go even lighter ( 40 - 50%?) and have more than a 2 overprint, but you would have to adjust your ink limiting so you don't get pooling/running inks on the media. hope this was helpful.

 

[Magman]

I find that i get the results i want when i do a 2 overprint method. before i send it to RIP i adjust the colors to between 85% and 80% or the originals so that the colors don't come out TOO dark when you're running a 2 overpass. We generally use a clear print media for illuminated sign box/face options, it is more vibrant and looks better in my opinion than a translucent white media. The colors will be a "little" darker than if you're running one pass during the day view, but it's usually not too different that the customer would notice. And if they are a more reserved customer, and "choosey"... lets not say the P word here, you can always offer to run them a sample print before production. I'm sure you could go even lighter ( 40 - 50%?) and have more than a 2 overprint, but you would have to adjust your ink limiting so you don't get pooling/running inks on the media. hope this was helpful.

Thank you we just did something else here that may be a workable solution. We put 60% diffuser on the acrylic face. We then put our print over that. This seems to help a lot, and if we play with ink saturations we should have a good working solution to improve this dramatically.

 

[Magman]

What are your passes like what kind of mode are you running? I saw a video once where they dull the lower layer then white then top is Normal do you do anything like that?

Our best result now is diffuser vinyl on the face of the acrylic, and then to overlay our print to that. Gets a pretty good results-- may be able to work with inks to make it even better.

 

[cornholio]

What are your passes like what kind of mode are you running? I saw a video once where they dull the lower layer then white then top is Normal do you do anything like that?

With those printers you can do CMYK-W-CMYK for backlit day and night use or even CMYK-W-K-W-CMYK for window application (the middle k layer is a light barrier that even allows different images front and rear)

 

[Magman]

Well we discovered with our UV printer we can run the panel through 2 or more times and get much better results. Also for vinyl, you can put down 60% diffuser product on the face of the acrylic and then apply your vinyl and it greatly improves the true colors shining through with less wash out of a look. Still not as good as using translucent mfg preprinted solid vinyl-- but you do get a better result with diffuser. I suppose with uv flatbed printing you can darken the inks on 2-3 passes. We tried 2 and it looked more acceptable. You can't run multiple passes confidently on your roll to roll printer-- so there I think you need to lay down more ink saturation via add extra CMY % per your rip.

 

[Krissy Louderback]

Okay, if this has been asked and addressed before I apologize.

I build a lightbox with a white polycarb UV coated panel. My digitial print is printed on a translucent printable vinyl. When not illuminated it is spot on beautiful. When I light it up. the colors are all washed out.

So I'm wondering how we keep the print vibrant when illuminated? I've attempted high pass Icc profiles-- help a little but not much... Does this occur due to the diffusing properties of polycarb and or acrylic? If so would adding Avery 30 or 60% diffusing vinyl on the inside?

I've printed on both Eco solvent translucent and my UV and both look ugly washed out once illuminated. What is the best way to get excellent results here with illuminated translucent vinyl , or should I print clear?

When looking at backlit films that looks awesome illuminated....???

 

[delriosigns]

Do you have a white channel in your UV printer?

We do 3 layered CMYK/W/CMYK and backlits look great when the lights are either on or off.

A little late to the convo, but I was wondering what translucent material you print on as well as what type of polycarbonate you use for 3 layered printing. I agree that 3 layered printing is best option for maintaining a consistent look during the day and night. I have however noticed that the signs are not as bright at night. I thought about using clear poly, but am afraid of visible LED hotspots. Is 3 layered printing on white polycarbonate the best overall option?