Well here is the first part of the routed sign that I did

These are the materials; I use Precision Board and there recommended bonding glue. In the end of the Panel I routed a grove for the aluminum bar only as deep as the bar is thick. Notice I left a little on the end; this is so the bar will not be pushed out by the glue when it expands and it makes the end cleaner looking.

I have found that the PB Bond 240 does not expand as much as the Gorilla Glue. I have not used epoxy but my experience with epoxy is the short "open" time and that it is very brittle. Also I found that the latex paint that I use or even oil based paint does not stick well to epoxy.

The glue is spread with a "squeegee" over all the area.

Then the mesh is put in place and also covers over the bar, all the way to the end. I apply a little extra glue on the edges with the mesh in place. It fills up the holes. The mesh is used in synthetic stucco. I buy it where they sell supplies for stucco; sold often at the same place they sell drywall supplies. When blasting HDU the removal of the material that gives blasted HDU its look causes the material to become flimsy. Thus the mesh gives the structural support that it needs without mounting it to a product that it not compatible, could ultimately fail.

The mesh is a fiberglass type mesh that is used in the base coat between Foam and stucco surface in synthetic stucco. I glue only one side dry. Presoak the 2nd piece and spray the 1st to activate...I have found that by gluing both pieces that there is too much glue and it really makes a mess.

Then the panel is wet to activate the glue. I have soaked the other panel that will go on top of this one I have glued, with a water hose to insure the bonding before laminating.

Then the panel is clamped and weighted down, the glue expands so this is a very important step to insure proper bonding as well as a possible deformation. Also an important thing is that the table that you glue using should be flat as it will take on the shape of the table.

The reason that I glue a bar in the ends is so that it will not tear when we install. Here is an example of mounting on brick using angle aluminum, tap coned into the wall and a carriage bolt through the sign with the interior aluminum bar.

I have heard of many people that are using MDO or die bond either on the back or in the middle of their HDU signs. In my experience I have found that this method is superior in strength, compatibility and weight. I even use this method with one sided sign. I'll use a thinner panel say 3/4" or 1/2" and then 1.5" or 2" for the front panel, needing that depth for carving or blasting.