Clear Vinyl for Outdoor Lightbox

[Jayefkay531]

I've read a bunch of threads about creating outdoor light boxes. Some people swear by translucent vinyl, some by dual layer (either both first surface or one first and one second), there's multiple theories. I've personally found that translucent tends to be washed out at night (or super dark during the day) and I hate having to register two layers - as a result, I've started printing on 3M 40-114 with a 260% saturation. I've found that during the day, this hits close to the needed pantone colors without looking washed out at night.

HOWEVER - what i've noticed is that there are sometimes grapefruit sized air pockets that form in the material. At first I thought it was outgassing from the polycarbonate, but we've seen it happen even after waiting a week for the polycarbonate to outgas. Has anybody ever seen anything like this before? Is there another way/material that would make this process easier?

Thanks!

 

[Dan360]

I've only ever seen this type of thing on the very first backlit sign I did, and it was because I didn't clean it well enough. We do clear Oracal 3651 on white poly/acrylic all the time. I can only think this would be caused by dirt or a small bubble that grows over time. Are you applying wet or dry?

 

[unclebun]

You don't have to do registration when you do double vinyl layers. Make your prints to be 1/4" smaller than the plastic panel all the way around. Trim them with a straightedge exactly on the edge line. Then you install the clear one (we don't do it wet because air bubbles won't show), then tape the translucent one right on top of it, lining up the edges, and stick it with hinge method. Fast and easy.

 

[Texas_Signmaker]

Pics?

 

[Jayefkay531]

I've only ever seen this type of thing on the very first backlit sign I did, and it was because I didn't clean it well enough. We do clear Oracal 3651 on white poly/acrylic all the time. I can only think this would be caused by dirt or a small bubble that grows over time. Are you applying wet or dry?

The 3M 40 is an air egress vinyl, so we never do it wet. It makes the installation super easy. I had considered that a small air pocket grew over time, but this happened on various substrates. I'd be hardpressed to believe that I'm failing to clean/miss air bubbles that often. I suppose it is possible though?

 

[Jayefkay531]

You don't have to do registration when you do double vinyl layers. Make your prints to be 1/4" smaller than the plastic panel all the way around. Trim them with a straightedge exactly on the edge line. Then you install the clear one (we don't do it wet because air bubbles won't show), then tape the translucent one right on top of it, lining up the edges, and stick it with hinge method. Fast and easy.

I had tried this in the past, but noticed that the translucent and clear have different levels of tolerance when coming off a latex printer - over a 12' run i've noticed almost a 1/4" of a difference in sizing. When aligning letters or images that have no ink next to them, this becomes visible...no?

 

[unclebun]

I had tried this in the past, but noticed that the translucent and clear have different levels of tolerance when coming off a latex printer - over a 12' run i've noticed almost a 1/4" of a difference in sizing. When aligning letters or images that have no ink next to them, this becomes visible...no?

That is something you fix in your media compensation so that prints always come out the size you intend. On our Epson, each media has its own settings so that we don't have to worry about discrepancy. However, even when we've had small differences in final size, the slight misregistration is inapparent.

 

[Jayefkay531]

That is something you fix in your media compensation so that prints always come out the size you intend. On our Epson, each media has its own settings so that we don't have to worry about discrepancy. However, even when we've had small differences in final size, the slight misregistration is inapparent.

Ah! I'll take a look for this setting and see what I can do. This will help for future instances, but I would still like to figure out why the 40C is doing what it is. I contacted my sales rep and 3M rep, both of which said they've never seen it before. The issues came from two different rolls - I suppose it's possible both were defective, but unlikely. Still has me scratching my head.

Thanks!

 

[unclebun]

I think the only possible explanation is you're not getting all the air out, and because of the air channels it all looks OK and smooth. But out in the sun, perhaps the edges are getting sealed before all the air comes out, so it eventually gets all collected in one spot.

As a test, apply some vinyl your normal way, then blast it with a hot hair dryer and watch the bubbles pop up.

 

[Jayefkay531]

I think the only possible explanation is you're not getting all the air out, and because of the air channels it all looks OK and smooth. But out in the sun, perhaps the edges are getting sealed before all the air comes out, so it eventually gets all collected in one spot.

As a test, apply some vinyl your normal way, then blast it with a hot hair dryer and watch the bubbles pop up.

That's actually an excellent idea I hadn't considered - I'll give this a shot and see what happens. Thanks!

 

[shoresigns]

One solution that no one ever talks about is white ink. We sometimes sub out our lightbox prints to a shop that has a printer with white ink, so they can do the double-layer (day/night) effect on a single sheet of clear vinyl. The printer prints a layer of colour, then white, then colour again. The colours appear normal during the day and the first layer adds density when they're backlit so the colours don't look washed out.

 

[unclebun]

One solution that no one ever talks about is white ink. We sometimes sub out our lightbox prints to a shop that has a printer with white ink, so they can do the double-layer (day/night) effect on a single sheet of clear vinyl. The printer prints a layer of colour, then white, then colour again. The colours appear normal during the day and the first layer adds density when they're backlit so the colours don't look washed out.

That's how we have flex faces done. But for commonplace 4x8 faces, it's easier and faster to just print them ourselves.