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I often read about or see signs that use HDU foam letters or panels and glue them to MDO or other surfaces. How do these signs hold up over time? I know that foam has little or no thermal expansion, while wood has quite a bit. Doesn't this cause "shearing" of some sort? At the very least, won't the paint crack around the bond site edges? What type of "glue" is recommended? What is the longest time that any of you have had a sign of this type out in the weather for? All feedback greatly appreciated. Cindy
------------------ Cindy Bennett Verde Valley Signcrafters Camp Verde, Arizona 520-567-3585
Just found out that I have something called Attention Deficiency Syn..Hey! Nice shirt!
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Hi Cindy. About 7 years ago, I fastened some letters cut fron SignFoam to a painted wooden structure using clear silicone calking. To the best of my knowledge, these are still in place and have held up quite nicely. This is in a Canadian climate that has ranged between -27 Celsius and + 32 Celsius.The silicone has enough flexibility and is waterproof. Apparently 3M now has some very aggressive 2-sided tapes that they claim will actually bond metal panels to metal supports. I'd call them to check out the technical data and perhaps they may send you a sample or two to test out.Hope this helps.
------------------ Ken Henry Henry & Henry Signs London, Ontario Canada (519) 439-1881 e-mail kjmlhenry@home.com
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3m does make a tape called vhb tape. it works excellently. silicome adhesive is very good for gluing letters to a background. we have done that, too.
cindy, paint all the pieces before you assemble them. paint the back of the letters, too. pounce your pattern on the background. put glue on back of letters. lay in place and let dry overnight.
same procedure if you are gluing them to a wall except, tape letters in place after gluing. remove tape when dry. you can also use aluminium studs on the back of letters if you want.
hope this helps you.
have a great one!
------------------ Bruce Bowers DrCAS Signtech
"how great are His signs..." Daniel 4:3
i am a proud supporter of this website!
Posts: 6451 | From: Saint Cloud, Minnesota | Registered: Jun 1999
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We have always had good luck with silicone adhesives bonding foam to wood and walls.
The only failure was bonding aluminum to medex on a brick wall with a full California southern exposure. There was just too much thermal expansion differential. We used 3M VHB, very high bond, for the repair and the letter stayed together
------------------ Victor Georgiou Bob Loves Signs Danville, CA email blssigns@verio.com
[This message has been edited by VICTORGEORGIOU (edited January 08, 2000).]
Posts: 1746 | From: Danville, CA , USA | Registered: Dec 1998
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I've done a few jobs like this using West System epoxy. MDO tends to be quite stable because of the cross-grained plywood core. On a single-faced sign I also set a couple stanless-steel screws through the substrate from the back into the backs of the letters, but this is more to pin the letters in place until the glue sets. One other thing - using this method, I fasten my letters BEFORE priming and painting the background. I want to count on the glue, not paint adhesion, to hold the letters on.
------------------ "A wise man concerns himself with the truth, not with what people believe." - Aristotle
When the going gets weird, the weird turn pro. - Raoul Duke (Hunter S. Thompson)
Cam Finest Kind Signs 256 S. Broad St. Pawcatuck, Ct. 06379 "Award winning Signs since 1988"
Posts: 3051 | From: Pawcatuck,Connecticut USA | Registered: Nov 1998
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Amen what Cam said about applying your epoxee to BARE foam. We had two sign faces nearly come down from the MDO substrate they were epoxee'd to. All but a couple of the West system "blobs" of epoxee on the backs of the 4'x6'x 3/4" faces had snapped off separating the top coats of enamel from the primer. Were we surprised! Some 25yr silicone solved the problem but now we always leave the MDO and HDU raw where they are to be fastened. While we thoroughly prime and paint the outer few inches of both materials, that center area is left natural for bonding. Whether it helps or not, we also scratch up the foam in the glue areas and add a few snipped off brads for good measure. Then the outer peremeter is sealed with a liberal bead of silicone all around to keep out any moisture. So far so good.
Another product we have been using a lot of lately for attaching appliques is polyurethane adhesive in a caulk tube. Man is that stuff strong! Foam to foam, foam to wood or wood to wood, it's like a universal fix. Still better to use on raw surface, though havn't had any failures even with painted pieces.
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