Bad MDO Boards

[Rookie]

Started using MDO for signs this summer. Went through a unit of 60 1/2-inch thick 4x8 sheets without incident. Also ordered six 3/4-inch MDO boards, from the same lumber company, for a pair of customers who wanted thicker signs. The two MDO 3/4-inch boards used for one of those customers apparently were defective. The customer emailed photos of the signs, and the top edges, despite proper caulking, had split after only five weeks (one terribly, the other starting to go). The lumber company contacted the manufacturer six days ago, and the lumber company manager sounds confident we'll be compensated and reimbursed the price of the signs (I sent them the customer invoice). He said he's never had a problem with MDO boards and was surprised by this.

This is the first time we've dealt with a seemingly defective substrate (we're only in our second year as a full-time sign business). How often does this happen, and how do lumber suppliers typically respond? Lastly, we have one 3/4-inch MDO left. Should we assume all of those 3/4-inch boards may be bad and ask for a credit and return it?

Thanks in advance for sharing your collective experience.

 

[J Hill Designs]

none of my sign suppliers carry 3/4" MDO anymore...

maybe this is why?

 

[WhiskeyDreamer]

my concern is that you used the term caulk....did you fill, prime and paint the edges of the MDO? If you just "caulked" edge capping on, this is not a defective material....

 

[Rookie]

If there's a void -- we have very few of them -- we fill it with caulk (we don't use edge caps, as most of our signs have curves we cut). We completely caulk the edges, then we paint them. So far, this has worked well.
Let me know if there's something more we should be doing.

 

[Mike Paul]

Send the last one back for a replacement or refund. Why take a chance of it being bad.

 

[WhiskeyDreamer]

You're still using the term caulk...do you mean, like caulk caulk? or something else?

i was taught to use a wood filler around all the edges, let it dry....sand it, use a tack rag to remove debris....prime the edges....if necessary a very light sand followed by the tack rag again....then coat the face of the sign with enamel and hit the edges....let dry....flip over and coat the back...hit the edges again....let dry...flip over and hit the front with its second coat.....

 

[JR's]

i was taught to use a wood filler around all the edges, let it dry....sand it, use a tack rag to remove debris....prime the edges....if necessary a very light sand followed by the tack rag again....then coat the face of the sign with enamel and hit the edges....let dry....flip over and coat the back...hit the edges again....let dry...flip over and hit the front with its second coat.....

that how we were taught to.



JR

 

[petrosgraphics]

we have used mdo for years... make sure it is 7 ply not 5 ply...

meaning there are 7 layers of plywood not 5.... you will find less voids, fewer holes...

fenris had it right... it all about sanding, filling, and painting...... not caulking.......

lumber yards will try to save a little money by selling only 5 ply.... ask them if they

order you 7 ply you will really see a dif.

 

[Gino]

As far as I know, caulk is never used to fill in the voids of any wood products.

The 3/4" and 1/2" duraply [MDO] we use generally has few voids if any. The lesser grade duraply has more voids. The 3/4" we use has almost no voids at all on any level.

Before you prime the wood, you should be using wood filler in the cracks. Put a little filler in the voids and slowly build them up until they're level with rest of the plies. Sand this down and then sand the faces lightly. Tack it and prime it. Once dry put a thin top coat on and paint the edges. After this coat dries, sand lightly with 220 or so and tack it again. Paint all the edges and your face with another light coat. It's up to you, but we use three top coats.

Anyway, let it dry for a day or so, then apply your vinyl graphics, silk screening or hand painted lettering and graphics.

If that delaminates, then you know you did your part thoroughly correct and the wood is indeed defective.

I must say this..... In almost 40 years of painting duraply [MDO] signs, I never had one delaminate yet. I've had polymetals and vinyl clad boards delaminate, but never one I or my employees painted. All of our employees know this procedure and adhere to it 100%. Again, sometimes we only use a prime and two top coats, but that's rare.

 

[Rookie]

Thank you all so much. As a newbie, much appreciated. Two things I'd like clarified regarding sealing: Is it recommended to use wood fillers only on the voids in the edges or on the entire edges (before priming and painting the edges)? And is wood filler, not caulk, definitely the way to go? I ask because on another thread, I'd asked which is preferable, and of the few responses, it seemed either or was fine. From what you guys say, and you guys really seem to know the craft, it sounds like wood filler is clearly the better way to seal edges, before priming and painting them.

 

[dj_elite]

I was a carpenter for 16 years and have been in the sign business for 2 years. I would never apply caulking onto wood then paint, even if it claims to be paintable caulk. Only going to cause problems...

 

[WhiskeyDreamer]

wood filler only...never caulk....

i'm sorry i didn't see the other thread, or i would have warned you against using caulk....

 

[Gino]

To fill voids and cracks in wood or plywood, you need to use a wood filler or putty. Whether it be solvent based or water based is not always the question, just do it correctly and allow deep holes to completely cure before adding more. Build up the deep voids and when everything is sealed... sand it.

Caulk is basically a substance used for sealing a crack between two surfaces... like a window pane to a frame or wooden planks in a ship of olden days. Not the end grains of planks or plywood.

 

[geb]

I will be in your area tomorrow and would be happy to stop and show what has worked for me, pm if interested.

George

 

[Firefox]

2 sheets out of 62, no too bad for doing them all wrong! :Big Laugh