The Letterville BullBoard: Need help with silicone/tape problem

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Posted by DesignsAndSigns (Member # 1951) on :

This is my first time posting here. We have a dilemma with an installation of a particular sign type.

The signs are 1/8" acrylic, with second-surface EDGE thermal print on high performance clear vinyl. The signs are then back painted with Matthews paint. An additional layer of high performance vinyl is then applied to protect the paint.

Signs were installed with double-stick tape and silicone to another piece of acryllic. Approximately 1 month after installation, the silicone has pulled the EDGE print from the acryllic, leaving bubbles and gaps.

We have done many signs in the exact same way in the past, and have experienced this problem sporadically. We never know if the problem will occur or not. Has anyone out there run into this problem, and found a solution? Thanks!

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James L. Greenlee, Graphic Artist
Designs and Signs Inc.

Posted by Pierre St.Marie (Member # 1462) on :

Your explanation evades me. Try again. What is the purpose of the paint and second layer of film?? Give me a step by step.

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St.Marie Graphics
& Makin' Tracks Sound Studio
Kalispell, Montana
stmariegraphics@centurytel.net http://www.stmariegraphics.com
800 735-8026
We're chiseling every day of the week! :^)

Posted by DesignsAndSigns (Member # 1951) on :

I'll try to be more descriptive. Our sign is second-surface, so we printed our thermal EDGE backwards onto clear vinyl, and applied it to the back of the acrylic. The Matthews paint was the background color of the sign.
The second layer of vinyl was to protect the paint from being eaten by the silicone and double sided tape.

This recipe works--most of the time. But, on occasion, we'll have a batch that sorta shrivels from the inside out. We don't want that to happen! Any ideas?

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James L. Greenlee, Graphic Artist
Designs and Signs Inc.

Posted by Robert Thomas (Member # 1356) on :

James,
Is the Matthews paint enamel or acrylic?
I'm doing some similar signs, back sprayed with Krylon, installed the same way with no problems. I didn't do the extra vinyl on back though, silicon right to the Krylon.

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Robert Thomas Creative Signs In Beautiful Naples, Fl.

Posted by Dennis Veenema (Member # 833) on :

I'm thinking it's more of a problem with the paint than the silicone. To me it's more like a curing problem with the paint. Since it's done in reverse then painted, and then you seal the back with vinyl, any gassing from the paint has no where to go.

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Dennis Veenema
The Sign Shop
Dresden, Ont.
&
GigaBytes Plus
"Where the plus is the service!"

Posted by Chuck Peterson (Member # 70) on :

Are these in the sun? It sounds like heat is expanding the plex making it want to grow larger than the underlying piece causing the adhesive to pull against the print. If this is the case, a solution could be to frame them so there isn't any adhesive on the back, they would sit in a frame with room to expand. I've done signs the way you describe on interior walls without a problem.

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Chuck Peterson Graphics
1860 Playa Riviera Dr.
Cardiff-by-the-Sea, Calif. 92007

[This message has been edited by Chuck Peterson (edited January 29, 2001).]

Posted by roger bailey (Member # 556) on :

I agree with Dveenema, You are probably trapping solvents from escapeing.
Roger

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Roger Bailey
Rapid Tac Incorporated
Waikoloa, Hawaii

Posted by Jack Davis (Member # 1408) on :

I belive it is also trapped gas. Would a shellac layer stick to the back of the letter? You may need a layer of protection from the silicone. Someone mentioned a type of super doublestick tape that you might be able to use alone without the silicone. A 3D L bracket type mount(epoxied to the edges of the letters) might be a choice ....Bronzeo

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Jack Davis
1410 Main St
Joplin, MO 64801

[This message has been edited by bronzeo (edited January 30, 2001).]

Posted by DesignsAndSigns (Member # 1951) on :

Thanks for your suggestions. The paint was our best guess too. It is "the way" in our the production department to "protect" paint with vinyl. Apparently, there have been problems in the past with tape and/or silicone eating paint.

Perhaps some of these signs were not allowed enough time to dry before it was applied, since only some of the signs are having the problem.

Thanks again.

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James L. Greenlee, Graphic Artist
Designs and Signs Inc.

Posted by Mike Pipes [in a cubicle] (Member # 1841) on :

James,

The paint could be a problem with the silicone if the paint hasnt gassed out yet, but there's also a few considerations concerning the silicone.

Like someone else mentioned, if there's alot of thermal expansion you'll have those problems but only if the silicone joint isnt made right.

Silicone is made to stretch but it wont if it's not applied right.
If you apply a bead of silicone then mash the panels together, the joint wont expand properly and it will pull the paint and/or vinyl up with it. This kind of joint acts more like a hard bond than it does an expansion joint.

In order for the silicone to expand and contract as it should, the depth of the silicone needs to be half of the joint width.
So, if you just mash the panels together with silicone in there the joint wont expand at all when it's subjected to heat, thus causing the joint to fail because the silicone WILL pull up but the bond between vinyl/paint/acrylic is weaker than a silicone joint.

Are these signs for exterior or interior? If they are interior I would say forget about using silicone cause the tape is strong enough on its own.
If they are exterior, then you need the silicone cause the tape will dry out and fall apart after time.

This falls right in line with the work Im doing right now under contract actually. I'm working at an engineering firm that designs window systems for large commercial buildings and silicone/foam tape is what holds all that glass on those tall skyscrapers across the globe!
I know it sounds pretty scary but a 1/2" bead of silicone around a 10' x 12' pane of glass is enough to hold 2600 pounds!
It's strong stuff!

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Mike Pipes
-----trapped in a box with a computer and a slice of cheese-----

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