Second surface graphics, adhesive issue on clear acrylic

[ragsxtags]

Hello, I recently took a project producing and installing some acrylic apartment door numbers. The issue I'm having is, a few days after completing the project the prints are showing what looks like an air bubbles or oil drops in various areas of the graphics (see pic). Seems to be happening to all the acrylics regardless of heat/light exposure.

I order a lot of my signage products from signs365, for whatever reason they do not direct print and cut acrylics less than 6x6" for these doors they had to be smaller. So, to do the job I ordered some clear acrylic rounds, ordered signs365 dualview for the graphics and installed them to each round (adhesive print side facing the acrylic).

Where I think I went wrong was with the mounting adhesive, for these I chose 3M 468MP to cover the full backside of the graphic, as opposed to a few squares of VHB (I thought the 468 looked better being flush to the door with thinner adhesive, and more coverage = more mounting strength)

Anyways, now I'm thinking there is too much adhesive on the backside of the print and it's pulling away from the acrylic side, creating the bubbling effect. Has this happened to anyone else, and am I thinking correct or is something else causing this? What are the solutions? (ideally without removal)

Thanks in advance!

 

[CanuckSigns]

Yes I've had this happen before, it's exactly what you think it is, the vinyl adhesive is pulling back from the acrylic due to shrinkage/expansion. Unfortunately I've found a full redo is needed, a direct print is the only way I've had 100% success.

 

[JBurton]

Where I think I went wrong was with the mounting adhesive, for these I chose 3M 468MP to cover the full backside of the graphic, as opposed to a few squares of VHB (I thought the 468 looked better being flush to the door with thinner adhesive, and more coverage = more mounting strength)

Well son of a gun, I was sure you just put a couple of piece of tape down and was going to recommend full coverage, which is exactly what you did... and man do I feel for you. I was pretty angry when just a couple out of 148 sign panels misaligned on my router, mostly cause the guy who did the art just jumbled the numbers all out of order.
Is the signs365 material air egress?
How long between applying the print, applying the 468, and installation?

 

[untitled]

I have had the exact same issue happen with 2nd surface acrylic photos that I've made and put what I am using to hang them directly to the prints. What ended up working was double sided taping a piece of thin pvc or sintra to the back and then adhering my mounts to that. Since I started doing that I haven't had an issue. The double sided tape is the larger rolls, not just small piece of tape. The tape fully covers the pvc sheet which then gets adhered to the back of the print. Then put your double sided tape on that for mounting to the wall/door etc. And yes it didn't make sense that it would end up working that way for me either, but for some reason it has.

 

[JBurton]

And yes it didn't make sense that it would end up working that way for me either, but for some reason it has.

I suspect that any 'give' that the print has to the acrylic is negated when it's spread across a semi rigid substrate.
Additionally, the door looks painted, so you'll have highs and lows, 468mp is thicker than 467mp, but they are both very thin layers, so any uneveness in the surface is going to cause less than uniform adhesion, which I imagine this picture shows the center was more adhered than the top, so it's tipping and pulling the material away.
OP may be able to save this project with a thin bead of lexel around the perimeter, but cleanup 100 times is no small feat.

 

[ragsxtags]

Thanks, there's actually only about 20 or so in total, still not ideal but could be a lot worse lol.

I installed the prints and then the 468 the following day, then waited a few days before installing on site.
Not sure about air egress specifically but the dualview is a thick semi rigid vinyl, so it was pretty easy to work with.

I'm thinking I can do a full redo, and instead place 3-4 .5" squares of VHB to mount each. Less surface area adhesive holding the backside of the print would stop the pulling from the front and the thicker VHB will let the acrylic float off the doors, staying even. Or will this give the same problem? Testing one now in the shop and seems to be working.

 

[JBurton]

Testing one now in the shop and seems to be working.

Unless your shop is hot as outside right now, this might not be a great test. I like untitled's solution, any sagging of the 3rd surface wouldn't show through to the second surface as long as it's rigid enough. Thicker tape would definitely help as well.

 

[untitled]

Thanks, there's actually only about 20 or so in total, still not ideal but could be a lot worse lol.

I installed the prints and then the 468 the following day, then waited a few days before installing on site.
Not sure about air egress specifically but the dualview is a thick semi rigid vinyl, so it was pretty easy to work with.

I'm thinking I can do a full redo, and instead place 3-4 .5" squares of VHB to mount each. Less surface area adhesive holding the backside of the print would stop the pulling from the front and the thicker VHB will let the acrylic float off the doors, staying even. Or will this give the same problem? Testing one now in the shop and seems to be working.

From my experience it'll work in the short term. Over time it'll do the same thing. The ones I did were for my own home and I did notice that it looked great, but then after a while I started noticing the bubbling again would creep back in. I was using pieces of wood to get the pictures floating off the wall. I tried gluing and VHB directly without any backer, I tried larger pieces of wood to try and spread out the pulling more. I ended up redoing these 3-4 times, I first tried adding 3mm ACM to the back and that separated, then the PVC and it finally worked and has been up for about 2 years now I think without any issues.

I know adding the PVC to all of them is going to be a lot more work, especially with having to cut it all, but it might be worth doing that once instead of having to redo them now and then end up having to do it again later. At the same time, those are a lot smaller than the ones I did, so it might just work out. I'm definitely no expert on these things, just some personal experience on my own stuff.

 

[bowtievega]

A couple of things:
1) If you are producing exterior signage with vinyl you need to make sure it is a high performance cast vinyl. The dual view vinyl Signs 365 sells is double sided window graphics with a low tack removable adhesive so hopefully you are not using that and you are just mixed up with the names.
2) We have absolutely had issues with expansion and contraction of ink and or vinyl on 2nd surface acrylic. Silicone is a great product for exterior installs because of its ability to grow and shrink while still keeping is bond but that is actually what causes problems in this instance as it will eventually start pulling the ink or vinyl off the back of the acrylic, especially outdoors and in the sun. For that reason, we typically reserve back printed signs for interior projects where we can install with just a tape product and no adhesive. We have found that VHB tape on the back of the prints doesn't cause issues for the most part. On certain jobs we will print copy and graphics on 2nd surface acrylic but back paint the background color to help reduce that issue as well. We also get the benefit of the color matching exactly with the other signs we would produce on that job so that is definitely a plus.

I think anything with vinyl on the back, mounted to an exterior door is just asking for problems. We would push for a 1st surface product like aluminum composite where the mounting is a non issue. Tape and silicone those things on doors all day long. We do a lot of that product with 1st surface print and clearcoat for exterior signs. If we need to do 2nd surface acrylic we try when possible to include a 2nd layer that you could tape the face to and eliminate the install problem. Always trying to up sell the client and make install easier for us when ever possible!