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We just had a 2- 1/4" double face come back, not more than 2,3 years old. All carved letters finished with gold leaf and black outlines, maroon background. The sign is 3'x 8', colonial shape. Both sides have cracked in several places, not hairline, larger. Before painting we applied the West System.
Has anyone experienced this? Does anyone know what went wrong? Where do we go from here? Any help would be greatly appretiated, thank you.
-------------------- Bill Riedel Riedel Sign Co., Inc. 15 Warren Street Little Ferry, N.J. 07643 billsr@riedelsignco.com Posts: 2953 | From: Little Ferry, New Jersey, USA | Registered: Feb 1999
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do you have any photos you could post? man this is the kind of shyt that scares me! so did you skim the whole sign with west systems? is it just the west systems that cracked or is it the hdu....do you know what brand hdu..signfoam, precision board or jasper? thanks...just trying to get a visual...could it have been vandalized?
-------------------- Karyn Bush Simply Not Ordinary, LLC Bartlett, NH 603-383-9955 www.snosigns.com info@snosigns.com Posts: 3516 | From: Bartlett, NH USA | Registered: Jan 2001
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If you coated the whole sign with West Systems I'd say that's the culprit due to expansion/contraction. Otherwise, I haven't got a clue. Got more details as to brand, density, installation, etc.
-------------------- Amy Brown Life Skills 101 Private Address Posts: 3502 | From: Lake Helen, FL, USA | Registered: Feb 2001
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I have no exact answers for your specific problems, but just thought I'd share my own and I do humbley note, very limited, experience, done years before I came to Letterville.
I have only done 2 (large) HDU sign panels, both 4'x6, only 1 &1/2" thick. (also have smaller ones)
Both signs are sand-blasted about 3/8 deep on both sides.
One of these signs is suspended between two large dryvit columns, and the other is suspended between two 6x6 posts.
I have always worried that they would simply break in two somehow. Bear in mind that the hot, humid southern summers and fast temp changes to winter and back again are pretty brutal. And I've worried especially since coming here and reading how people glue sheets together for strength and thickness, and include internal supports.
I have never heard of 'West systems'. Although from reading here, I gather it is some sort of epoxy paint.
All I did on both those signs after they were sand-blasted was prime the bare HDU with 2 or 3 coats of a good grade latex primer. There are at least 2-3 finish coats of industrial oil-based enamel as well, and I used oneshot for the lettering & logos.
One sign is over 8 years old and the other is over 6 years old.
Both signs faces are still in excellent to very good shape, although the oneshot lettering has pretty much flattened & faded.
One of the columns blew over during Ivan. I did'nt build the columns, but the 4x6 sign fell away off at at odd angle as well and I was sure it cracked or broke, although it still looked solid, not bent or warped. Before I even had a chance to stop by, the Apt. complex had the damaged column repaired. Everything, including the dryvit columns were simply re-painted & the original sign re-hung.
I'm still not totally comfortable with the concept of 'dense styrofoam'. It just ain't redwood. Just the idea that an adult or a rambunctious kid could just run right through it, or at least put a serious dent it . . .
But the signs I see made with the stuff are just incredible. And I have a job coming up that would be ideal for it's use again.
I would like the sign to be thicker, so I might try gluing two sheets together. I definitely have questions about that procedure, but as far as painting, and even if I can sell some gold-leaf on it, I think I'll stick with the same general fabrication and painting guidelines that have worked just fine on the other jobs.
I dunno if this means diddley-squat to your situation.
I think I said all that to say, SOMETIMES these hi-fa'lutin' systems are not as good as just regular ol' paintin' ways.
All that said, mabey it was vandalism or an accident where the thing got hit hard. One major problem we have with sign damage to all kinds of signage here comes primarily from sloppy lawn mower driving by maintenance people.
You sure have our attention on this subject. Could you provide a little more information, specifically with any lamination, interior supports, etc.
Joe
-------------------- Joe Crumley Norman Sign Company 2200 Research Park Blvd. Norman, OK 73069 Posts: 1428 | From: 2200 Research Park Blvd. | Registered: Sep 2001
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OK folks, thanks for the attention. The sign has a plywood center and was laminated by using the West System as an adhesive, and the surface was coated with the same West System before painting. The cracks have a different pattern on each side and the HDU is lifting slightly in spots. The brand of HDU is Precision Board. The finish is One Shot Maroon. I hope this helps.
-------------------- Bill Riedel Riedel Sign Co., Inc. 15 Warren Street Little Ferry, N.J. 07643 billsr@riedelsignco.com Posts: 2953 | From: Little Ferry, New Jersey, USA | Registered: Feb 1999
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Is the surface of the HDU coated with epoxy, then painted? If so, did you wash-off the "amine blush" (film left on epoxy after it cures), before painting?
Any particular reason for coating with epoxy prior to painting?
Where is the HDU lifting from? The plywood?
Are the cracks in the epoxy, or HDU?
Peace out, Bob
-------------------- "The 3-4 minute mark of "Freewill" by Rush.
Bob Kaschak Artisan Sign And Design Peru New York Posts: 1873 | From: Upstate NY | Registered: Jul 2002
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Are you concerned that plywood expands, while HDU doesn't?
Joe
-------------------- Joe Crumley Norman Sign Company 2200 Research Park Blvd. Norman, OK 73069 Posts: 1428 | From: 2200 Research Park Blvd. | Registered: Sep 2001
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Bob, the reason for coating the HDU was to seal it's million tiny holes. The coating and the HDU both are cracked and lifting from the plywood. Mostly cracks and a few places where it is lifting. Not a pretty sight.
-------------------- Bill Riedel Riedel Sign Co., Inc. 15 Warren Street Little Ferry, N.J. 07643 billsr@riedelsignco.com Posts: 2953 | From: Little Ferry, New Jersey, USA | Registered: Feb 1999
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Bill I would highly recommend not coating an HDU sign with epoxy.
A quality primer, either water based or oil based (I prefer water based), and a quality paint, either latex, or oil based (I prefer latex), will do just fine filling in those tiny holes.
As a matter of fact, most all substrates need to "breath". If they are completely sealed with something like epoxy, they will find a way to give and take moisture, usually resulting in a failed finish.
I know most people will say "HDU doesn't take on moisture", and for the most part, that is correct, but if it is laminated to another material, there are differences in expansion/contraction rates, and moisture does get in and out of finishes, it's supposed to.
Just like building a fine piece of furniture, the finish allows the wood to breath, while protecting it.
If you are concerned with having a smooth finish, then try to always use a high density HDU, such as 18, or 22 lb. It has a tighter texture.
My preference is Signfoam 3. I haven't had an HDU compare yet with it's quality. It's worth the little extra cost.
As far as fixing what you have, it might need a complete replacement. It is going to be hard to get that epoxy off without damaging the HDU itself.
I hope this helps.
Peace out, Bob
-------------------- "The 3-4 minute mark of "Freewill" by Rush.
Bob Kaschak Artisan Sign And Design Peru New York Posts: 1873 | From: Upstate NY | Registered: Jul 2002
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i hope this will help. i glue using gorilla glue and mesh(used in stucco for base coat) between my panels. The mesh give the supportthe you are looking for and keeps the weight down. I glue a section of flat bar in the edge.i rought a groove as deep as the alluminum flat bar. the flat bar is there so not to tear the HDU when installing with bolts and angle alluminum. then use angle to attach to column or post. also to mount to the wall,
i have fallen i love with panelclips for mounting on a flat wall...and have used them with HDU. check on this page of my web site and you'll see how i used panel clips to mount a 8'x12' HDU panel to a wall.
posted
Just had a visit from Ray Guzman of Hoboken Signs and Brain Waves. He was talking to Chuck Miller of Sign Foam and he said the only way to solve the problem is to glue the panels with lines of Gorilla glue vertically, keeping away from the edge. It means that there has to be air between the panels. The other thing is that any MDO will expand and contract differently than the foam..
Thank you Chris, the pictures are great, and thank you Bob, you have been very helpful
-------------------- Bill Riedel Riedel Sign Co., Inc. 15 Warren Street Little Ferry, N.J. 07643 billsr@riedelsignco.com Posts: 2953 | From: Little Ferry, New Jersey, USA | Registered: Feb 1999
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I too am sorry to hear of the HDU failure. Hope there is some way to make it work.
Hey Chris the photo's you posted on the link are very good. I agree with all the your steps as well as the panel clips. There a great product.
Here are a few observations.
HDU doesn't like to be laminated to wood, plywood, plastic, or any other product that expands and contracts at a different rate. Over time, it will sheer away or warp. It also doesn't like bolts very much. Kelley at Coastal E. has a good bolt throught process with epoxy.
Aluminum tubes, glued and embeded seems to be a very affective. I've had good results with this also.
Joe
-------------------- Joe Crumley Norman Sign Company 2200 Research Park Blvd. Norman, OK 73069 Posts: 1428 | From: 2200 Research Park Blvd. | Registered: Sep 2001
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ok now i'm confused...i've had a # of reps and plenty of professional sign people tell me that epoxying raw hdu to raw mdo is just fine and they have never had a failure. i've also read it in many signcraft articles.
-------------------- Karyn Bush Simply Not Ordinary, LLC Bartlett, NH 603-383-9955 www.snosigns.com info@snosigns.com Posts: 3516 | From: Bartlett, NH USA | Registered: Jan 2001
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Me too. I've seen articles in most of the Magazines where HDU has been attached to most everything.
With the passage of time, we are finding more and more failures. Some of our signs fair pretty well, but others have warped and or sheer at the joint.
Letters laminated on MDO seem to do the best, but panels that stretch some distance have all warped. It's just the physical trait of expansion.
Do a test for your self with a narrow skinney scrap 6'or 8' long and watch it bow.
Joe
-------------------- Joe Crumley Norman Sign Company 2200 Research Park Blvd. Norman, OK 73069 Posts: 1428 | From: 2200 Research Park Blvd. | Registered: Sep 2001
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Since I'm getting ready to start a job using the HDU, and as mentioned before, I have questions and doubts as well.
Also, the idea of MDO or plywood, even treated plywood in between a totally different material that does'nt have any kind directional grain at all has never appealed to me or even made logical sense...although, to be fair, I know lots of illogical things work just fine everyday..ie; Airplanes, marriages...etc...
OK, SERIOUSLY NOW . . .
here's MORE questions:
1.The particular job I have coming up is going to need the 'thick' look, but I'm thinkin' the HDU material comes 3" thick so I may be able to avoid gluing at all. Is that a correct assumption??
2. Is Gorilla glue the only glue to use for laminating?? What about using Max-Bond or Liquid Nails???
3. Has anyone had problems over-time after attaching changable name plates? (In this case, tenant names, probably on aluminum plates, will be attached and I'm a little concerned about removing and re-attatching so frequently as to eventually 'wall-out' the screw-holes in the soft HDU.) Please share your experiences with this.
4. Can you please describe (or show http's) imbedding reinforcement rods in HDU? It makes sense how it might be done if laminating two sheets together, but what about a 3" thick peice? Is reinforcment unecessary in that case??
5. On both the signs I described earlier where we suspended panels between two posts via brackets, (very similar to what Chris showed) we drilled the hole slightly larger than the bolts allowing for expansion. But Joe's comment about HDU not 'liking' bolts has me wondering: What kind of problems have bolts caused in HDU?
5. Can anyone offer feedback, suggestions, or warnings on the following idea:
A 4x8x3" HDU sign mounted between two brick columns where the sign panel will be vertical, standing 8ft tall and about 3ft off the ground between the columns. The top 3ft (roughly) of the sign would actually be above the column tops.
6.Should I be concerned about that 3'x4'x3" un-supported area of the 4x8???
ALSO, I'm thinking of using a peice of angle-iron across the bottom of this vertical sign which would be barely visible (attached from column to column) to help support the downward-weight and then 4 large decorative brackets near the center and bottom on each side (similar to angle-iron side brackets)
7.Does any of this sound sufficient to hold this material without imbedded reinforcement??
Thanx in advance for any advice.
-------------------- Signs Sweet Home Alabama
oneshot on chat
"Look like a girl, act like a lady, think like a man, work like a dog" Posts: 5758 | From: "Sweet Home" Alabama | Registered: Mar 2003
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I've been laminating hdu over mdo for 15 years without a failure. The average thermal expansion co-efficient of mdo is very small - practically negligible.
-------------------- Steve Purcell Purcell Woodcarving & Signmaking Cape Cod, MA
************************** Intelligent Design Is No Accident Posts: 900 | From: Cape Cod, MA | Registered: Oct 1999
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sheila...i would not suggest using hdu if you are going to be attaching and changing out name plates...once a screw goes in and out...it will have nothing but sugar to grip to.
joe...i can only hope and pray the few i have out will survive..lol. none are bigger than 7ft in length.
also when people say plywood...do they mean plywood or mdo....i use mdo. i know someone that only uses 3/8 plywood in between hdu...and west systems them together. i admit i'd be scared about that...but they say its fine. i guess time will tell.
i do have my next sign coming up thats one sided but will be installed between granite posts and the backside will get all the sun....i was thinking of skimming a coat of epoxy on the mdo then painting it. the hdu will be 1.5" thick...and i always use 18lb. now i wonder if thats a good idea. i will only prime & paint the front of the hdu...and i may go latex with this one...trying the porter acryllics if i can find them. then again who knows...i have to paint two partridge with detail so maybe i'll end up sticking to one shot....i'm sooooooooooooooo confuuuuuuuuused!
-------------------- Karyn Bush Simply Not Ordinary, LLC Bartlett, NH 603-383-9955 www.snosigns.com info@snosigns.com Posts: 3516 | From: Bartlett, NH USA | Registered: Jan 2001
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Karyn, I was thinkin' the same thing about the changable plates.
My next idea would be for the whole thing to be made of dryvit and have the internal studs aligned so as to the be able to screw the plates into those.
The logo could then be sandblasted HDU attached to the arched face on the top-part of the sign, making it even more dimensional . . .
Decisions, decisions . . . .
-------------------- Signs Sweet Home Alabama
oneshot on chat
"Look like a girl, act like a lady, think like a man, work like a dog" Posts: 5758 | From: "Sweet Home" Alabama | Registered: Mar 2003
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shelia, the sign that i show earler is 3" thick(2 4x8 panel x1.5"thick). i would would install it the way i showed with the flat bar aluminum in the middle and the aluminum angle bracket. with the stucco mesh glued between the panel you would be suprised how strong this makes it and i found it very hard to break.i have not had the need to attach a backing to HDU but if i did i would use .060 or .080 aluminum. using a high bond laytex primer then 100% acylic finsh.
i would not use the liquid nails as most of them are interior adhesive and some are not compatable to the HDU but... PL brand polyurethane adhesive is awesome and stayes flexable(home depot or lowes). but if you do not put the mesh between you are not getting any strength...the Gorilla glue expands and fills all the voids but be carefull to have enough weight when you glue. to make edges smooth.... tool elastromeric caulking were the two panels come together.
as far as the monting of the changable sign you might want to inbed the flat bar aluminum in the place that you will be installing the sign thus using the same hole and use sheet metal screw and hole pattern for each new install.
i'm an oil based man from way back but with this urathane HDU use the 100% acylic laytex is the best and only way to go. plus use what the manufacture suggest for the primer.
chris
-------------------- "We have been making house calls since 1992"
Chris Lovelady Vital Signs
NOW WITH 2 LOCATIONS! Tallahassee, Florida Thomasville, Ga.
There are so many ways people are working with this product I understand the confusion.
Here is the way I have come down on it:
I use 15lb for my faces but use 18lb for the applied, carved pieces. For the faces I use 1 1/2" stock and with spacers on the interior of the sign from the same scarps. For legnthy panels I use aluminum square tube glued into place with epoxy. The back is also from 1/2" or 1" HDU. All glued up with PB's or Gorilla's glue. So the whole thing is HDU panel, usually 4 to 6" deep. Aluminum tubes are used on panels longer than 4' long.
For Sheila's question on removable panels. We have done pretty well by glueing redwood or cedar panels on the interior of the sign where the screws will go. Karyn is correct about the HDU not being a very good material to screw to.
We've also used wood blocks, Epoxy'd on the interior ends of signs where bolts are required for pole mounting.
I will send you a photo of a sign or two.
We use latex paint, inside and out.
I know there are lots of different techniques for using this material. This is only ours and seems to hold up well. HDU really requires non traditional methods when it comes to attaching it to other materials. After some real failures like Bill's we've had to rethink our techniques.
Good luck,
Joe
-------------------- Joe Crumley Norman Sign Company 2200 Research Park Blvd. Norman, OK 73069 Posts: 1428 | From: 2200 Research Park Blvd. | Registered: Sep 2001
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Using screw-in threade inserts is how I do changable panels. I use the brass ones because they don't rust. I put a dab of "never sieze" on brass machine screws to keep them from binding up.
You have to take a bit of care to make sure you don't strip out your hole with the inserts. I suggest you get a couple of extras to play with to get the feel of how they work.
-------------------- Bruce Bowers
DrCAS Custom Lettering and Design Saint Cloud, Minnesota
"Things work out best for the people who make the best of the way things work out." - Art Linkletter Posts: 6451 | From: Saint Cloud, Minnesota | Registered: Jun 1999
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Most everything that has been said is right. The first thing being that HDU DOES EXPAND AND CONTRACT. Not alot, but enough that you need to be creative about production and installation methods. An once of prevention... Sheila, no matter who the manufacture of HDU, I would recomend using 2 1.5" pieces and laminating them together. 3 inch material is not readily available and is relatively expensive too. By laminating 2 pieces, you can route a couple of grooves in the back of both signs and lay in either pipe, threaded rod or angle iron extending them past the ends of the sign to use with the mounting device. As for mounting name or tenants panels straigt to HDU, you can drill larger holes in the background sign and glue in nuts or screw sets. Then screw the name panels from the front, making them changeable. As for gluing into, onto or together, the best bonds are from urethane based glues, ie: Gorilla Glue, Pro-Bond, PL-Construction Adhesive, Lord Adhesive - 7400 Series, etc. You can laminate raw HDU to raw HDU with one of these products, preferably one that is a 100% urethane based product. Also, because HDU manufactures recommend painting all surfaces equally, the paint you use on the surface must stick to the glue you use when gluing anything to an HDU sign. It is also recommended NOT to use any constrictive type paints as well. Bottom line, the more experimenting that is done in the market place, the possibility of occasional failures. It is smart to use tried and true methods or to test theories on smller panels yourself. And most importantantly, contact manufactures before taking chances with something your not sure of. The profits availible with HDU signs are worth expanding your boundaries and moving outside your confort zone. My 2+ cents worth, John Meeks, (Sign Guy and HDU guy)
-------------------- John P Meeks The Sign Shoppe, Inc. Everwood 200 Brozzini Ct. Greenville, SC 29615 864-275-5140 Posts: 44 | From: Greenville, SC | Registered: Oct 2004
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I never really understood why plywood was ever used as a backer or stiffner for HDU considering plywood's potential negatives.
For myself, if I had to laminate two pieces for increased rigidity, I have always just routed a slot for inlaying aluminum angle or steel rods and epoxied it all together.
posted
I have seen several signs that were 3" thick, that were just HDU, with no backer, that were vandilized, and they broke easily.
I would not install an HDU sign with no backer in a college town where some kid on his way back to the dorms at 2am, decides to give it a swift kick. That sign would snap easily.
If the sign had an MDO backing, it would hold-up just fine. Sure, the HDU would probably dent, but the sign itself would survive fine.
I have single and double sided signs with different colors on front and back, of all different sizes, with no signs of bowing or delamination.
Could the problems that others are experiencing from poor quality MDO?
Could the problems stem from a different amount of coats of paint on the front compared to the back?
Too thick of MDO compared to HDU?
Maybe too much of the surface of the glue up is coated with adhesive?
Just some food for thought.
This is a great post with a lot of good info being shared.
Solo mi dos centavos.
Peace out, Bob
[ August 13, 2005, 10:56 PM: Message edited by: Bob Kaschak ]
-------------------- "The 3-4 minute mark of "Freewill" by Rush.
Bob Kaschak Artisan Sign And Design Peru New York Posts: 1873 | From: Upstate NY | Registered: Jul 2002
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Serioulsy, thanx for all the valuable and wise information.
But what else would one expect from you bueno ombre`s?
Thanx Chris for the awesome step-by-step on the mounting clips! Man! That was a huge sign to accomplish hanging via ladders! I'm a little freaked-out over seeing a ladder aginst the sign face!
But I'm very impressed with how everything lined up perfectly! I saw this sign in the SOTM and now considering the size and how this pretty difficult install went so smoothly, I'm wondering if we should have an 'installation' catagory!!!!
So, now I'm off to draw-up the design and figger and price the job both ways: Dryvit and Hdu. Wonder how close . . .are far apart, the time involved and final numbers will be!
-------------------- Signs Sweet Home Alabama
oneshot on chat
"Look like a girl, act like a lady, think like a man, work like a dog" Posts: 5758 | From: "Sweet Home" Alabama | Registered: Mar 2003
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IVe been using mdo as a backer since I started doing sandblasted signs several years ago. No problems with warping or adhesion. Ive used west systems epoxy,(the best for the job) and gorilla glue. I like em both, but would prefer west systems most of the time. I scuff up the surface of the mdo before gluing, and put little small indentions in the hdu for the glue to run into. Im pretty sure I would never put up a sign made out of hdu without some sort of backer, due mainly to vandalism and wind, etc. One of my friends who is an excellent signmaker, put up a beautiful sign last year without a backer, we had a really bad windy storm and it pulled it right out of the bracketts. Due to the area it was being installed, there was no problem with vandals or anything else. I might have done the same thing, but wouldnt now. Broke that sign right in two.
-------------------- Maker of fine signs and other creative stuff. Located at 109 N. Cumberland ave. Harlan, Ky. 40831 606-837-0242 Posts: 4172 | From: Ages-Brookside, Ky. Up the Holler... | Registered: Jul 1999
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Sheila, Why not just apply the panels to the face with Double-Backed foam tape? It will hold well, and can be removed with a wire, when (if) necessary.
-------------------- Gene Golden Gettysburg Signs Gettysburg PA 17325 717-334-0200 genegolden@gettysburgsigns.com
"Art is knowing when to stop." Posts: 1578 | From: Gettysburg, PA | Registered: Jun 2003
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Bob, I too question the quality of the MDO. I've had difficulty getting it from my normal supplier recently. I guess the demand for other plywoods has them running short on MDO at the manufacturer level. Ya gotta wonder if they may be shipping out green lumber on MDO.
Most MDO failures are from moisture damaging the laminates in MDO. Almost every time, layers will seperate becaues the edges weren't sealed right. If the lumber is green, the moisture is still in the wood and it gets sealed in with nowhere to outgas.
In Bill's case, I can't help but wonder if the wood was green. Sealed in the epoxy and painted dark, it would act like a pressure cooker on the MDO and accelerate the expansion/contraction rate a bit more.
Just a theory... Rapid
-------------------- Ray Rheaume Rapidfire Design 543 Brushwood Road North Haverhill, NH 03774 rapidfiredesign@hotmail.com 603-787-6803
I like my paint shaken, not stirred. Posts: 5648 | From: North Haverhill, New Hampshire | Registered: Apr 2003
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Bob, I have to just incorage you to glue 2 peices of HDU together with the mesh and then try and break it. you will be suprized.
Shelia, thanks for the kudos. the ladder on the face was no problem with the rubber booties. no need for any touch up from the ladder. the install was like hanging a picture...really. i had an artical in signcraft this issue on the install. this is an awsome installation hardware and have used it many times.
chris
-------------------- "We have been making house calls since 1992"
Chris Lovelady Vital Signs
NOW WITH 2 LOCATIONS! Tallahassee, Florida Thomasville, Ga.
posted
Chris is very right about fiberglass mess. Ted Gore from West Systems brought a piece to the Dixie meet that was about 8"x24" and only 1/2" thick. He had it mounted about 3 inches off the ground and I could not break it even by jumping up and down on it.
Good Luck!
-------------------- John P Meeks The Sign Shoppe, Inc. Everwood 200 Brozzini Ct. Greenville, SC 29615 864-275-5140 Posts: 44 | From: Greenville, SC | Registered: Oct 2004
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I agree that the mesh works for stability, still sometimes, most of the time for me, I want some dimension to the sign. When I first started using HDU I would use treated wood to give my sign some depth, then back it up with 3/4" MDO. It wasn't long before I came to realize there were seperation problems.
For many of our group warping, doesn't seem to be a problem. Use what ever works for you. I now make all our panel sign, front, back and interior from HDU. We use scraps to build depth on the sides, top and bottoms, and for the back we try to get the 3/8" stock used as a protective shipping cover. This is usually 18lb. and is free when available.
I only wish the manufacturers of HDU, would have given us more information about the expansion co-effecients and recommendation as how to glue up panels years ago.
Perhaps Everwood has a technical bulletin with suggestions about what substrate materials work the best.
Joe
-------------------- Joe Crumley Norman Sign Company 2200 Research Park Blvd. Norman, OK 73069 Posts: 1428 | From: 2200 Research Park Blvd. | Registered: Sep 2001
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quote: I only wish the manufacturers of HDU, would have given us more information about the expansion co-effecients and recommendation as how to glue up panels years ago.
The SignFoam people have, for years, been producing a fairly extensive technical manual.
Personally, I think that most hdu failures are attributable to "pilot error".
-------------------- Steve Purcell Purcell Woodcarving & Signmaking Cape Cod, MA
************************** Intelligent Design Is No Accident Posts: 900 | From: Cape Cod, MA | Registered: Oct 1999
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Hi everyone! I apologize for seeing this post so late but I'm on vacation. (thanks Barb for sending the link) You've all asked a lot of great questions and I've read a lot of great answers and techniques. I'll try to answer as much as I can.. (from memory of reading..lol)
When another product is bonded to the back of HDU (any Mfg) the difference of expansion/contraction of the two unlike products should be taken into consideration. It's a good idea to use a rigid urethane adhesive, (PB Bond, PB Fast Set) or an epoxy but Do Not do a full face bond. You'll want to apply the glue around the perimeter (1/4" bead) about 1/2" from the edge. Then run a vertical bead every 8" or so up and down the back of the sign. The reason for this, and why it's so important, is if one of these products need to expand or contract quickly, it will break the glue line and not the HDU.
Everything expands and contracts at different rates and HDU is much less than others. We've always had the CTE of Precision Board on our data sheets and if you'd like us to figure it out for your individual sign, then please call.
You'll want to bond raw material to raw material because your bond is only as strong as what you bond it to.
When sandwiching another product in between HDU, we recommend using a product that doesn't absorb water because this will add a lot of expansion and movement.
If you'd like more mounting and strengthening ideas, please look at our web site, or better yet, call us! That's what we're here for. If I haven't answered the questions you'd like, please let me know. Thanks, Kellie
-------------------- Kellie Miller Customer Service Mgr. Coastal Enterprises Company Mfg. of Precision Board (800) 845-0745 www.precisionboard.com hdu@precisionboard.com Posts: 118 | From: Orange, CA | Registered: Feb 2002
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Thank you so much for assisting us on this question.
So what happens if you glue a full 4'X8' sheet of 3/4" MDO to the back of full sheet of HDU. Will it warp or sperate?
Joe
-------------------- Joe Crumley Norman Sign Company 2200 Research Park Blvd. Norman, OK 73069 Posts: 1428 | From: 2200 Research Park Blvd. | Registered: Sep 2001
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Well, you can bond a full sheet of MDO (though MDO absorbs a lot of water) to the back of Precision Board, but be sure to apply the adhesive (rigid adhesive, not something flexible) to the back of the sign the same way that I mentioned above. If you have too much glue (full face bond) then you won't allow for the expansion/contraction differences and it will crack the HDU. Please seal all the edges of the MDO. If you use a flexible adhesive, you have a better chance of separation, which could allow the HDU to warp. (because of the paint tension from the paint) If you have more questions about paint tension or how HDU works, we have a training video for the FSC-88WB primer on our web site. It goes over a lot of those type of things.. I hope that answered what you needed. Missed you in Mazeppa! -Kellie
-------------------- Kellie Miller Customer Service Mgr. Coastal Enterprises Company Mfg. of Precision Board (800) 845-0745 www.precisionboard.com hdu@precisionboard.com Posts: 118 | From: Orange, CA | Registered: Feb 2002
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