Looking for advice on sealing edges on overlaid plywood signs. I am currently repairing a sign I did 2 years ago, the edges are flaking and the paint is falling off. I applied exterior wood putty to the edges , primed , then painted using a good sign paint, I'm surprised it didn't last longer?
I notice some people are using caulk and epoxy, besides wood putty, I just curious what the pro's are using
Thanks Todd
Posted by Raymond Chapman (Member # 361) on :
Well, I'm not sure what the pros are using but this is what we do.
Our procedure is always changing...and hopefully improving.
Right now we round over the edge of the MDO with a 1/4" round over bit and then seal the edge with Titebond III glue (applied with a stiff stencil brush or woodworkers glue brush - we buy them by the gross and throw them away after use).
When dry we fill the voids with exterior spackling or wood filler. This is all sanded and then two coats of latex primer is applied, followed by two coats of finish (100% acrylic latex).
So far this has been working, but nothing seems to be the perfect answer.
Some have used West System epoxy but I never seem to be able to get it very smooth and it's really sticky...which is not a bad thing unless you have it all over you, like I usually do.
[ January 12, 2007, 06:04 PM: Message edited by: Raymond Chapman ]
Posted by Todd Land (Member # 1179) on :
Thanks Raymond, I checked out Titebond web site and the glue looks like a very good product. I'm going to try it definitely on the repair job I'm doing and my upcoming projects.
Thanks Again PS You guys are PROS! Posted by Michael Boone (Member # 308) on :
easy dont use plywood
AND...more important.. dont fix old plywood signs
ya have aluminum/baked enamel dibond omega board
this comes from a fellow New Yorker.......
Posted by Doug Bernhardt (Member # 1568) on :
Just sticking my nose in for sec....Raymonds method sounds right with the exeption of the spackling filler if you live in northern climates. You'd want to use bondo instead. Process would be something like...fill edge gaps with bondo seal with titebond or epoxy...paint
Posted by Bruce Williams (Member # 691) on :
I have a strange Q: Should we seal the bottom edge of wood at all? I always do. Bit I'm told that the bottoms of fence-rails are left bare at the local Bluegrass horse farms. Supposedly, this lets water drain out and not concentrate at the bottom. (?)
Posted by bruce ward (Member # 1289) on :
I got to go with michaael on this....why are you people still using plywood, WHY? MDO sucks! No need to bash me for this I would just like to know. Doen here we pay
maybe its just down here but mdo splits, peels and dont last at all anymore. When you buy it, its already warped. and then on top of that all this saning priming, bonding....I just dont get it
Posted by Stephen Deveau (Member # 1305) on :
Bruce
Well there is one thing I like to ask you!
When a tree drinks water,.. is it from the ground up or the rain down.......
Wood is no different from a spounge. If the core is not sealed it will take anything into it..... like moisture.
Prep is the only way to insure it! Like the bark on that tree it needs premanent sealing. I would use a Varathene with a mini roller at least 3 times around the edges before prime and painting.
Posted by Kelly Thorson (Member # 2958) on :
There is absolutely no "Magic" way to do this. Actually there probably is, the big guy must be asleep on the job. In any case I just dropped in to say that whatever you use, if you knock the sharp edges off all the corners with either a router or sandpaper, you'll find that the paint will seal better. When the sealers and paint dry the skin pulls tight across those areas and you will find they are the first part to fail. Once that happens the moisture is in. It is a little more work, but especially here in extreme climates well worth the time. Cut corners elsewhere. Posted by Tony Vickio (Member # 2265) on :
I'm with Boone! I don't have a piece of MDO in the shop!
Posted by Raymond Chapman (Member # 361) on :
This thread is a great example of what works in one place is not necessarily perfect for everyone.
Here in Texas we have a lot of heat in the summer but not unusually high amounts of moisture.
PVC will warp almost before you get the tools back in the truck, but we use it a lot for interior works.
Coroplast will turn brittle and crack. Certainly not a bad choice for interior or short term use. We normally use 1/2" and it works well for temporary signs.
.040 aluminum is a good choice except it must have some kind of backing to keep the waves from forming. We normally use .080 aluminum but the price is closer to finished MDO.
Even with all of its problems, MDO is still a good material for our area...when finished properly. There are various grades of MDO, just like any other material. The best that we have found is Simpson Two Step...which is now Olympic, I believe.
For both exterior and interior projects we use a lot of 30# Precision Board HDU and now are experimenting with Duna Corafoam.
Dibond is another choice but dents easily. The jury is still out on long term, but we use it in some cases.
Omega board has seen some use in our shop, but we've experienced some delamination, so it has gone by the wayside.
So, Bruce...you said you just wanted to know...and now you know.
Posted by George Perkins (Member # 156) on :
quote:Originally posted by Bruce Williams:
I have a strange Q: Should we seal the bottom edge of wood at all? I always do. Bit I'm told that the bottoms of fence-rails are left bare at the local Bluegrass horse farms. Supposedly, this lets water drain out and not concentrate at the bottom. (?)
Bruce, the reasoning there is to have an unsealed edge to allow the moisture to escape. The bottom of the fence rail doesn't show. The line of thinking is moisture is gonna get into a sign/fence and eventually it's gonna try to get out. If all the edges and faces are sealed, it may just push off the face. I read something twenty or thirty years ago regarding peeling paint on signs. It recommended NOT painting the back side of the sign, giving the moisture an easy escape route. I used this method whenever possible for years and never had a peeling problem. When leaving the back unpainted wasn't feasible I used the Bondo method. I didn't have a bit like Raymond talked about but I would round the edges with a sanding block. I used to be a body man and a sanding board makes quick work of sharp edges on a 4x8.
Posted by Tim Whitcher (Member # 685) on :
Why use MDO? 3/4" MDO is a lot more rigid than .040 aluminum when mounted between posts. Aluminum is going to require some kind of backer, unless you're mounting on a near perfect flat surface. MDO cuts easily, and dents and scuffs can be repaired easily. A dented sheet of aluminum and you're screwed. MDO can be bought preprimed, so requires little prep. Since 80% of our sign backgrounds are anything but white, we would be top coating aluminum anyway. The best alternative to MDO is Dibond, and we are using more of it. If you're getting warped MDO, time for a new supplier.
Posted by Graham Parsons (Member # 1129) on :
Anyone else use edge capping for MDO? We still prime and paint the edges but use a plastic capping on a lot of MDO panels.
Posted by Stephen Deveau (Member # 1305) on :
Raymond.. you speak truth about the area and conditions we are installing graphics and signs.
Notice of materials To many times we are dealt with the product at hand. (Best Price for return!)
I don't think of the item as a one off! But more to the point of resale if needed.
[ January 13, 2007, 09:19 PM: Message edited by: Stephen Deveau ]
Posted by Dale Feicke (Member # 767) on :
Obviously, a lot of the new materials on the market offer different advantages over MDO. But, considering the prices of some of them, I'm sticking with the old stand-by.
I buy it pre-primed, like someone else said. Takes little to finish coat. If it gets damaged, bondo takes care of it. Damage an aluminum panel and you're screwed. PVC warps badly here in the south, and in some cases, yellows with age.
I guess it's what you get used to. I've used wood glue, fiberglass resin, acrylic primers, and lots of other stuff to seal the edges. Now, I do it this way....Acrylic primer...do the edges first...roll the back.....let it dry...flip.....do the edges....roll the front...let it dry....color coat....do the edges....coat the front...let dry....do the edges....coat front again.....done. That makes four coats of paint on the edges. Should be enuf. Voids are filled first with Elmer's carpenter wood filler or bondo.
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In any case I just dropped in to say that whatever you use, if you knock the sharp edges off all the corners with either a router or sandpaper, you'll find that the paint will seal better. When the sealers and paint dry the skin pulls tight across those areas and you will find they are the first part to fail. Once that happens the moisture is in. It is a little more work, but especially here in extreme climates well worth the time. Cut corners elsewhere. 