posted
Pictured below is a sign I completed only last fall...as you can see...from the pictures I have been sent...some unusal damage has occurred...it has happened the same to both sides and neither side is caved in...both sides are cracked and exploded outward...one side has cracked and lifted out more than the other...I'm assumming that one has a southern exposure but I'm not sure...the maintenance man I have talked to...who seems extremely knowledgeable and over qualified for his job...has assured me that there is no indication of vandalism but rather the damage seems to have resulted from unusal stresses within the sign itself...I'm hoping you guys can shed some light on this problem.
this is how the sign is constructed
---------------------------------------------- this is the e-mail I got back from my inquiry with David at Industrial Polymers...see if you agree with his assessment...or maybe you have had this happen to you...or maybe you have a different idea as to why it happened in the first place..and how in the heck am I going to repair this so it doesn't happen again...I have to figure this problem out because in this coming year...2011...I have orders for 6 apartment signs using this same tree. ------------------------------------------------
Hello Rusty,
I think this problem is caused by heat cycling of the darker colored sign and trapped moisture vapor inside.
This sign must be getting very hot in direct sunlight for this to happen, the ProtoCast 80R casting became hotter
that the rest of the sign surface. The high density Urethane foam is blown with water vapor at the time of manufacture.
When the sign became hot the coatings applied to the foam surface prevented the moisture vapor from easily escaping
from the laminated structure. If I am correct the bowed areas should be bowed out like a big blister with the tree casting sitting
ontop of the blister formation. If the delaminating were caused by expansion of the wood, there would be no blistering, sheering instead.
The ProtoCast 80R has taken a heat set in this position but I don’t think it shrank on the sign causing the delaminating,
Nor do I think the plywood somehow shrank or expanded causing this. The high density urethane foams have a great deal of residual
moisture and it doesn’t usually cause problems, but this laminated structure was so tight the moisture vapor became hot and expansive.
I have seen this happen many times before in urethane roofing applications when a top coating is applied over the spray applied foam
which cannot breath and allow the foam to vent out the moisture. In roofing applications it typically strips the coated foam off the roof deck
resulting in large blisters.
You may have used an epoxy or urethane based coating over the foam which cannot breathe.
If the ProtoCast 80R had shrunk we would have likely seen the delaminating between the tree casting and the high density urethane foam
it was bonded to. If I am correct simply gluing it back down may not solve the problem, the structure will need to be vented as well.
posted
It definitely looks as if the tree has pulled into itself tearing out the sign. Good for the Magic Smooth - it looks like it did it's job. I'm not at all familiar with the casting material, but if it is like a fiberglass resin I've had experience with them bowing when exposed to sunlight. To me it looks like that is what happened. I'm not sure what your mold is made of but is it tough enough to cast Magic Sculpt? Another option might be to mount your casting on a plasma or waterjet cut steel backing and pin it to the HDU. There must have been some pretty good tension on the HDU to pull it apart like that, but I'd guess it was definitely caused by shrinking/curling of your cast.
-------------------- “Did you ever stop to think, and forget to start again?” -Winnie the Pooh & A.A. Milne
Kelly Thorson Kel-T-Grafix 801 Main St. Holdfast, SK S0G 2H0 ktg@sasktel.net Posts: 5496 | From: Penzance, Saskatchewan | Registered: May 2002
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-------------------- “Did you ever stop to think, and forget to start again?” -Winnie the Pooh & A.A. Milne
Kelly Thorson Kel-T-Grafix 801 Main St. Holdfast, SK S0G 2H0 ktg@sasktel.net Posts: 5496 | From: Penzance, Saskatchewan | Registered: May 2002
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I've seen HDU actually made.......no water involved.
HDU is a GREAT insulating material....a heated surface (from the sun) doesn't get very far into the HDU. Pluss, the cells are closed.....moisture can't migrate through it.
IMHO, the casting shrank.....look at the pattern of the crack......very much follows the shape of the tree.
Solution......casting should be mounted so that, in the future, it is allowed to shrink and expand. Mount it on pins with a small air space between the back and the substrate. If it warps, it will pull on the pins and won't rip up the HDU behind it.
Of course I'm no expert on this, but I did sleep last night at.......hmmmmm, where WAS I last night?????
Joe,
Makin Chip$ and Havin Fun!
-------------------- Joe Cieslowski Connecticut Woodcarvers Gallery P.O.Box 368 East Canaan CT 06024 jcieslowski@snet.net 860-824-0883 Posts: 2345 | From: East Canaan CT 06024 | Registered: Nov 2001
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posted
I might tend to have to agree with David,, But.. Have you been able to see the sign yourself. Cause by looking at your casting if the tree was warping you should see signs of stress cracks in your paint. Like spider webbing in fiberglass. I have seen resin shrink and crack when poured but that's usually on pours 4" thicker or more and even at that if your tree was warping it would/should crack at your weak spots. The Branches. But Stranger things have happen and I have no experience using resin in your Humid areas so that is adding another new variable.
On your next casting you may try adding some fillers, Micro balloons to lighten it up or Micro Beads or Potash to make it heavier
posted
I've never seen anything like that before in the approx. 10 years of making HDU signs. What David said seems to make sense. I think Kelly's suggestion of pin mounting the tree would be the way to go. Sorry, that doesn't help the existing sign dilemma. It's a great looking sign.
-------------------- Jean Shimp Shimp Sign & Design Co. Jacksonville Beach, Fl Posts: 1265 | From: Jacksonville Beach, Fl. USA | Registered: Nov 1998
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posted
From what I see the wood grained portion of the sign was just too thin. The magic Sculpt obviously shrank a little putting some stress on the sign.
I would have made this sign with inch and a half material leaving more thickness for the cody of the sign. I would also have used 30 lb foam which is much stronger too.
-grampa dan
-------------------- Dan Sawatzky Imagination Corporation Yarrow, British Columbia dan@imaginationcorporation.com http://www.imaginationcorporation.com
Being a grampa is one of the the most wonderful things in the world!!! Posts: 8738 | From: Yarrow, B.C. Canada | Registered: Nov 1998
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posted
Just tell them that there is no charge for the "extra 3D" and walk away. Kidding aside Rusty. I hope you find out how to fix it and sorry to hear that happened.
Happy New Year!
-------------------- Charles Borges de Oliveira Borges Lettering & Design Snohomish WA Posts: 352 | From: Snohomish WA | Registered: Mar 2003
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First off, let me say I know how sick you must feel about this sign blowing apart like that. It's gorgeous.
I've had a similar experience with sandblasted HDU. In fact, when I saw the photos it brought back a most unpleasant experience of my own.
I've been making signs with HDU for many years and have only see this happen once. In my case, it was on a sign that I constructed exactly as you built yours...two faces laminated to an MDO core... a method I considered bulletproof at the time.
It was installed at an elevation of 9200' above sea level and the south side did the same thing. I didn't have any appliques on it as you did but it failed in exactly the same way. It looked as though it had been pushed out from the reverse side in a "bubble" that then burst, leaving a cracked and raised areas in the face.
I was puzzled and called everyone I could think of, including the good people at Sign*Arts who made the HDU. No one was any help as none of their explanations made any sense. I think that's the case with David's reply. It makes no sense to me for the very reasons pointed out by Joe C. It's likely he's referring to a different type of urethane material.
Finally I was left with the only answer I could come up with and that was that the HDU warped from the intense heat gain from the sun and caused the construction adhesive I had used to affix the foam to the core to fail. I had no way to fix the existing sign so I had to replace the broken face, this time adhering the foam to the core with a solid, wall-to-wall coat of epoxy.
You know, as I reread that last paragraph I was thinking how surprised I was that Gorilla Glue failed. Then it occurred to me that right there may be where the problem is. Gorilla Glue foams, of course, as it dries. It could be that in doing so it trapped enough moisture and/or air to cause an expansion when sufficiently heated. (Except this doesn't explain the localized failure).
I wish you luck in this problem, Rusty. It's going to be a real interesting story to hear how you rectify this situation and how you deal with this nightmare in your subsequent signs.
God, it's always SOMETHING in the business.
-------------------- Brian Oliver Paxton Signs Fort Collins, CO paxton@peakpeak.com www.paxtonsignsofcolorado.com Posts: 237 | From: ft. collins, colorado,usa | Registered: Mar 2001
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posted
this is just a tidbit of info about differences of expansion from heat an cold.
Years ago a building was finished with huge glass panels. Those glass panels were bonded to metal frames via a metal that was directly bonded to the glass. There was no room allowed for any movement at all. The following spring the glass started flying out of the frames leaving the bonded metal / glass combination behind. They could actually measure the bow in the glass with a straight edge. It was like someone had cut the glass by outlining the bond.
It was determined that the glass worked itself against that bond and there was no allowance made for the difference of expansion with the glass and metal.
All the panels were replaced with new frames allowing for the differences of expansion. No more problems.
Whats this got to do with a sign panel?
It looks like the same problem. That entire cast piece was bonded so well to the foam it finally worked the weakest point until it gave way. It pulled out a chunk of foam.
We drill over size holes when attaching plastic sheets to a surface for the expansion problem. yes?
-------------------- Leaper of Tall buildings.. If you find my posts divisive or otherwise snarky please ignore them. If you do not know how then PM me about it and I will demonstrate. Posts: 5273 | From: Im a nowhere man | Registered: Jul 2001
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posted
Glenn...if you'll scroll back up to the diagram you'll see the sign construction and thicknesses...(1"hdu face...1/2"mdo core...1"hdu face)...gorilla glue was used with 45 "c" clamps around the perimeter and ten 60 lbs. bags of sacrete distributed evenly across the faces during gluing...each face was a separate gluing...I don't know exactly how thick the HDU was after sandblasting and I am hours away from this sign...but for sure it was thinner and the weakest link in the chain...in fact that is where the breakage has occurred...scroll up to the 2nd and 3rd pic and you can get a rough idea of the HDU thickness that was left...however I didn't think this mattered...I thought all these materials were more or less inert and there would be little movement...at least not enough to matter...Evidently I was wrong and I'm still mystified...apparently I don't understand these materials like I thought.
posted
Charles...thanks for the levity...times like this a little humor is good medicine...I'll try to get to some of the other questions that have been asked later as I appreciate everyone's imput.
Everything you did was right. The only unknown is the casting. It's hard to tell in this pic, but that casting is REALLY BIG!!!!! 3' plus wide??? and how thick?
Another clue pointing to the casting is the HDU only pulled away on one side.....the weakest side. Once it broke away, the tension was relieved and that was the end of the de-lamination.
Fix?? I would use a die grinder and remove the tree. Glue the HDU back into place (with the MDO core, you can use screws to pull it back into place).
Cast a new tree with 1" screws imbedded in the back and remount in oversize holes filled with silicone.
Good Luck (this really sucks!!!)
Joe,
Makin Chip$ and Havin Fun!
-------------------- Joe Cieslowski Connecticut Woodcarvers Gallery P.O.Box 368 East Canaan CT 06024 jcieslowski@snet.net 860-824-0883 Posts: 2345 | From: East Canaan CT 06024 | Registered: Nov 2001
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posted
Joe..the plastic cast tree measures 42"x18" and is 1.5" at it's thickest and tapering down thinner at the edges...Industrial Polymers has said they would still recommend Protocast 80R plastic for it's weathering properties and cost...it is relatively inert and if the tree had shrank more than likely we would observe breakage in some of the bottom branches which are the thinnest and most fragile long before the HDU would have cracked...seems to make sense...also Industrial Polymers said that a relatively thin piece of plastic like this left on it's own might warp in the sun...however it would not possess the strength to break the HDU and can easily be held down with proper adhesives...in fact it can also be heated and bent to different shapes...so I think these facts rule out the plastic casting itself as being the culprit...I'm thinking it's going to be an odd combination of factors...mostly dealing with heat...that all came together just right for a "the perfect storm" scenario...so now metaphorically...I have to repair after the storm and figure how to rebuild so as to survive the next one.
posted
My appologies, Rusty. I was juggling a couple things and totally overlooked it. I should have paid closer attention.
I have to agree with Dan.
Just some personal thoughts....
I've never been a big fan of using any organic material (mdo) as the sign's core for the sake of adding rigidity to a HDU sign. My personal preference in your design would have been to have used two sheets of 1.5" HDU with some 3/4" - 1" square aluminum tubing sandwiched in between. I just run a router on the backs of the panels to create the necessary groove to accept the tubing. I just let the tubing float (no glue). Then mate the back of the two panels together with epoxy or gorilla-glue.
I've done this with several HDU signs and never had a failure.
I realize this doesn't help you now, but hopefully it will help someone in the future.
The sign you did is absolutely fantastic. Its sad to see something like this happen to something so beautiful. I hope everything works out for you.
[ December 29, 2010, 07:08 PM: Message edited by: Glenn Taylor ]
posted
I was just going to say the same thing as Joe, but worded differently, till I read what he wrote; that's after I copied the first two lines of Brian Oliver's post...
Lovely sign! Horrible thought about the failure! I feel for you. Right now fixing it is the issue, as well as stopping it from happening again.
It has let go where the HDU is glued to the MDO, caused by the resin reacting to the sun's heat.
Some solutions are to have better a better bond glue/screws/whetever sticking the treed part of the HDU to the MDO. More or stronger HDU in that area may well be a solution, but technically the glue has let go in that area, so better adhesion is needed somehow, in my opinion.
The first question is are you going to bring it all home & keep it & make them a new one, or are you going to try & fix it largely as it is?
Secondly, if fixing it, will you bring it home, or try & do it onsite? If bringing it home, I'd consider using broad-headed screws to hold the tree back down to the MDO, as well as epoxy resin glue for the repair, then disguise the broken join line. Actually, if it's broken like that on both sides, can you drill right through from one side to the other & put some washered broad-headed bolts through to pull it back down into flatness. Countersink or recess the bolts a bit & fill the recess in the tree up with automotive putty.(We call that stuff 'bog' here-it's like quick-setting 2 part glue plus talcum powder & a reddish hardener).
Did the faces face east/west, or north/south?
The final issue is preventing it from happening to future signs- as said by others- by having a more bend-resistant backing to the tree, & a more substantial substrate around it, & stickier glue or maybe countersunk bolts as well, for insurance.
PLease keep us informed!
Edited to add you've typed as I was typing, and I see you feel that shrinkage of the tree wasn't really a cause. I find the trapped moisture idea a bit 'fishy', personally & still tend to go with the bulk of the mass in the tree being affected by heat & cold as the largest factor.
It's all a big concern anyhow.
Could you use future trees routed in HDU, the same as the rest of the sign?
Or attach them on a sort-of shield-shaped frame/panel in the centre, so that if there's to be a junction where movement may happen, it's given a place to happen which you don't try to disguise. (Using the "If you can't hide it, then make a feature of it" theory?)
[ December 29, 2010, 07:23 PM: Message edited by: Ian Stewart-Koster ]
-------------------- "Stewey" on chat
"...there are no limits when you aim for perfection..." Jonathan Livingston Seagull Posts: 7014 | From: Highgrove via Toowoomba, Queensland, Australia | Registered: Dec 2002
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posted
I'm still not convinced.......the tree didn't shrink as a whole.....it warped. The face of it shrank a bit and pulled the rest of the casting and the HDU with it.....foward, like a board when it cups.
Personally, I'd take a new casting and hit the face with a heat gun......see what happens. Nothing like a test to eliminate guesswork.
Sorry to be a PITA.
Joe,
Makin Chip$ and Havin Fun!
-------------------- Joe Cieslowski Connecticut Woodcarvers Gallery P.O.Box 368 East Canaan CT 06024 jcieslowski@snet.net 860-824-0883 Posts: 2345 | From: East Canaan CT 06024 | Registered: Nov 2001
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posted
I wouldn't necessarily say that the casting shrank. My gut is that you had three different things expanding and contracting at different rates - the HDU, the casting and the MDO. I imagine that the panel absorbed a tremendous amount of heat and something had to give.
posted
Glenn...since this sign was built I no longer use the MDO center...I have replaced it with the aluminum signboard that has the rubber center...you guys are going to laugh at me but I don't know what it's called...howz that for a sign man...the sign blank you put together sounds great and I see myself evolving to that end in the future...the added cost is a factor I have to consider...however I can be convinced.
posted
Ian...I'm going to try and repair on site if I can...I'll know when I get there...it is several hours from home...your suggestions are greatly appreciated and I'm sure I will incorporate them into my repair...really good suggestions.
posted
From the image you posted it looks as if the MDO delaminated. Isn't that the face of it stuck to the HDU? Have you not done a number of signs before using the same substrates minus the casting?
If it was caused by moisture trapped inside I would think it would only have pulled away far enough to allow the moisture to escape, once it cracked the pressure would be off. But I am just speaking from my own logic not any knowledge or experience, other than one in which I cold cast an 8" x 18" resin panel that was only about 3/8" thick and mounted it on 6 mil glass. It bowed and broke the glass.
"If I am correct the bowed areas should be bowed out like a big blister with the tree casting sitting on top of the blister formation. If the delaminating were caused by expansion of the wood, there would be no blistering, sheering instead." To me that looks more like a shearing than a blister.
Even if you don't think the casting bowing is the culprit, as an extra caution I think the idea of pin mounting the casting in oversized holes with silicone is a good one. Another idea would be to hollow cast the tree - that would use less material anyhow and it wouldn't have near the expansion contraction strength. You could fill the void with something like spray foam.
I too, am sorry to see this happen to that beautiful sign. It also makes me nervous about some of the stuff I have out there. I hope you can get it fixed without too much hassle.
-------------------- “Did you ever stop to think, and forget to start again?” -Winnie the Pooh & A.A. Milne
Kelly Thorson Kel-T-Grafix 801 Main St. Holdfast, SK S0G 2H0 ktg@sasktel.net Posts: 5496 | From: Penzance, Saskatchewan | Registered: May 2002
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posted
I don't think that it's MDO that pulled away with the foam/and tree casting.... looking at the diagram, it would seem to be the "Magic Smooth"... which I am unfamiliar with... but I think the MDO is what you see left behind, with some striated Magic Smooth partially stuck to it.
Rusty - that just kills me to see your beautiful work in that condition. I'm sure it makes you sick, but hopefully you can figure out the problem and take the good advice here for the next go-round.
I think I remember you posting this sign before - it's a beauty. Hope you're able to repair it with minimal effort.
-------------------- Todd Gill Outside The Lines Potterville, MI Posts: 7792 | From: Potterville, MI | Registered: Dec 2001
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posted
Oh... and I'd be very curious as to how you would seal your sign from the elements, yet 'vent' it... other than pinning the casting away from the foam as suggested?
-------------------- Todd Gill Outside The Lines Potterville, MI Posts: 7792 | From: Potterville, MI | Registered: Dec 2001
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posted
I've read and reread this post several times, trying ot think of what might have caused this. My gut reaction was the casting shrunk or curled. But just for thought, considering a moisture trapped issue, was the MDO primed? It looks like it was not. And if not what if any moisture might have been trapped in the MDO? Is it possible that the MDO had moisture trapped in it?
That is of course going down the trapped moisture road. I recently bought my own moisture meter. And as a rule I buy reprimed MDO to reduce any moisture that might be picked up on a truck or in a warehouse before it gets to me.
Just a different twist.
[ December 30, 2010, 05:10 AM: Message edited by: Bob Rochon ]
-------------------- Bob Rochon Creative Signworks Millbury, MA 508-865-7330
"Life is Like an Echo, what you put out, comes back to you." Posts: 5149 | From: Millbury, Mass. U.S. | Registered: Nov 1998
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posted
Kelly...I have yet to see the damage in person and I have wondered the same thing as you...is that the top layer of MDO I see still laminated to the back of the broken HDU?...I'll give them a call tomorrow and ask for clarification on the pic...in comparing the 2 above photos that were sent to me I'm thinking on the closeup they must have manually lifted the broken section out far enough to photo behind the break...that's another question I will ask tomorrow...at this point everything is still speculative...I suppose there could have been an initial blistering or swelling before it popped open to relieve the pressure leaving the broken edge protruding...the casting is partially hollow on the back though not as much as it could be...and finally I have yet to hear a better suggestion for future mounting than the raised "pin mounting" with metal back from your very first post...thanks
posted
Bob...there was definitely moisture involved in my glueup...and maybe we're onto something...the MDO and HDU were gorilla glued together...on one surface glue was spread...on the other water was misted before clamping and applying pressure as the instructions state...the MDO was not primed as I thought it unnecessary and maybe the unprimed surface would even hold the glue better.
Here is my current theory as to why this happened...this is only a theory as much of this has to be assumed on my part...I welcome revision from anyone here in Letterville...feel free to add or subtract...here goes .....................the chemist at Industrial Polymers states that the plastic tree casting is very stable and would not have sufficient strength to produce the damage as seen in the photo...the tree casting is 42" long and 18" tall...a pretty good chunk of dense plastic...it could have collected heat at a far greater rate than the surrounding HDU sign surface which obviously handled the same weather conditions with no adverse effect...we have 2 different materials...a dense plastic casting glued to HDU...I'm guessing the light and rather open grained HDU doesn't heat up greatly...and I'm guessing that the dense plastic does...if this is correct then the added heat could have tranferred to the internal part of the sign only directly behind the plastic casting...this area could have had temps considerably greater than those throughout the rest of the sign...great enough that the trapped moisture which was added to activate the gorilla glue expanded, blistered and popped at the weakest point...that being the thin sandblasted background around the tree...maybe the moisture content in the other parts of the sign remain in some balance and pose no threat because they dont heat up as much...just guessing here.
If these heat and moisture assumptions are correct....then I'm wondering if epoxy...which would have no additional water added...had been used instead of gorilla glue this might not have happened...or if the tree had been made of HDU (less heat absorbed) it might not of happened...or if the plastic tree were pin mounted off of the sign surface as Kelly suggested (less heat absorbed) this might not have happened...maybe even the heat up difference between an east/west facing sign and that of a north/south one would have made the difference...and I'm thinking this was a north/south facing sign...this might have been the "prefect storm" so to speak...several factors coming together contributing to this failure...had only one of those factors been different this might not have happened...what ya think...does this scenario sound plausible.
posted
That's a heartbreaker for sure. We never sandblast here. We laminate the HDU to 4mm Dibond, and we get a far more believeable woodgrain effect doing it by hand with our woodgraining tools. We even carve small knots into the surface. We can also do it in 1/4 the time or less than it takes to sandblast it and with little mess, if any.
Doing it that way we can control the structural integrity of the substrate, if its 2" thick, it stays 2" thick overall with just the surface woodgrained 1/16th to 1/8th" deep.
We never laminate large objects to the surface with adhesives. We put the woodgrained substrate on the CNC, program and rout the exact shape of the object, or dimensional letters just deep enough to go below the woodgraining. We use our "push through" function on the CNC for a perfect fit. It also looks very cool to see the heavy woodgraining run right up the the edges of the copy or dimensional carved artwork
We run screws through from the back into the object or dimensional letters. Fitting the objects down into the routed area, we pull them down flush with the screws.
Aside from the minimal number of screws, each item is a unit unto itself, allowing for a small nominal amount of expansion and contraction.
If you don't have a CNC it can be done easily by hand with a pattern and a standard dedicated router. We have 4 diferent sized hand routers set up with surface slides and handles. They're not used a lot since the CNC, but Dad still does once in a while. He hates automation, unless its a machine gun.
Sorry for your troubles with that one Rusty. Very nice piece.
posted
This is an inane unexciting project we put together for a real estate developer. The woodgrained piece was done exactly as I described. The woodgraining is heavier in this one because the developer chose it for the woodgrain visibilty at distance.
All of the dimensional copy and logo is slightly recessed and screwed from the back.
These are samples of the woodgraining we do.
Maybe this approach or some part of it will help you, Rusty.
posted
As a demonstration of how simple things can have a great impact on products where expansion and contraction are concerned:
In 2005, I purchased a new Chevy Silverado Quad Cab 4X4. After a short time, I noticed the body-side moldings on each door had developed a rectangular shaped 'bump' which showed as a raised area on the moldings.
Being a 'visual' guy like everyone here... it bugged me. I thought, "My moldings have developed Leprosy."
So, knowing they were adhered with double-sided 3M foam tape from the factory.... I pulled one off.
Guess what? Corresponding to the exterior 'lump' was a small part # rectangular paper sticker on the back-side of the molding.
I instantly knew that this small sticker was providing just enough insulation to alter the expansion/contraction properties of the polymer molding in that particular location.
I pulled the rest of the moldings off and witnessed the same thing: Every lump in the molding corresponded to the part # sticker on the reverse side of the molding.
I pointed this out to the Dealer and told them to call GM and tell them this.... and the Dealer told me that replaced the molding on their trucks regularly and couldn't figure out why the lumps were forming. Now they knew.
Being under warranty, they gave me the new moldings and I told them I would install them... so I just took the moldings, removed the sticker from each and installed them on the truck.
No more lumps developed....
-------------------- Todd Gill Outside The Lines Potterville, MI Posts: 7792 | From: Potterville, MI | Registered: Dec 2001
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posted
Latigo...that's some pretty incredible work on your site...the size of some of the carved signs is incredible and what outstanding engravings...your work is something to be extremely proud of.
posted
Gee, Todd, you could have asked fpor a whole new truck instead-it 'could' have been the truck that was causing the bumps in the moulding...
-------------------- "Stewey" on chat
"...there are no limits when you aim for perfection..." Jonathan Livingston Seagull Posts: 7014 | From: Highgrove via Toowoomba, Queensland, Australia | Registered: Dec 2002
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I've read this post numerous times and I'm sure I've still missed some things. If so, I apologize.
You have various substrates here that are expanding and contracting at different rates. I'm glad that you're not using MDO anymore, since it moves a lot and holds a lot of moisture. HDU does not hold any moisture and as Joe mentioned, is closed cell and doesn't absorb anything. It also doesn't expand/contract as much as other substrates.
First question I have (and this is what I might have missed) -How was the MDO and HDU adhered? Did you apply as a full face bond? Did you allow for any movement?
I'd like to see other pictures and try to help you fix this. As others have mentioned - it's a beautiful sign and sorry that you're going through this.
I'll be back in the office on Monday - I'm not sure I have your phone number so can you please call me?
Thanks and Happy Holidays to everyone! ~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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posted
If those tree castings are over 3ft wide, using them for scale reference the rest of the sign must be pretty big!
Seems more like a wind/deflection issue than a thermal expansion issue. a sign that big definitely will move in the wind. The added thickness of the castings will cause local stress as the rest of the sign tries to bend if the castings do not bend with it.
Pin mounting the casting or using a zig-zag of very flexible adhesive would allow for movement.
-------------------- "If I share all my wisdom I won't have any left for myself."
Mike Pipes stickerpimp.com Lake Havasu, AZ mike@stickerpimp.com Posts: 8746 | From: Lake Havasu, AZ USA | Registered: Jun 2000
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posted
Mike...thanks for trying to help...but if you could see the sign in person I think you would rule out wind as a factor...it is good size though...but not that big...and very rigid...it measures 7'x 5.5' and 2.5" thick...which includes a 1/2" MDO core which gives considerable rigidity.
for how log did you let the tree sit and dry after casting? Did you heat dry it? Is it possible to have not enogh hardener in that material. That would make drying time a lot longer. It maby would be good, to pot it in the oven and then sand it from the back to make it flat again to glue..........just an Idea.
When you glued the MDO to the HDU, did you spread the glue on the "entire" surface, or were there any areas without glue?...example..(did you glue the perimiter of the sign, but not glue towards the center?)
I'm curious if there are any areas of glue and no glue that could be an issue?
My guess would be expansion/contraction between the MDO/HDU.
Does the sign seem to "bow" to one side more then the other, or is it flat?
Best of luck in resolving this.
Peace, 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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yep. the MDO is warping and taking the HDU along for the ride (as Sign Foam states on their website). The glue is doing it's job but the foam has no choice but to crack from the stress. We've had this problem alot recently and are about to switch to Alumalite.
-------------------- Bruce Evans Crown Graphics Chino, CA graphics@westcoach.net Posts: 910 | From: Chino, CA | Registered: Nov 1998
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