Sign info on material and "sandwiching"

The first "sandwich " sign I made was a learning experience and cost me a bit ! But like they say "a good education is never free".

I made a double sided HDU sign using 2 1.5" sheets of precision board . Between these I put a MDO spine in and joined it all together with 6 beads of Gorilla glue.
I placed plywood accross sawhorses and put the sign on top. Then another sheet of .5" plywood. On top of this I put 8 1 gallon cans of paint to keep it together.
When I got back the next day everything looked great !
I put a vinyl frame kit together and readied the sign for delivery.

The glue in the center had never set up completely. When I came back from luch the Gorilla glue had THEN expanded and ooozed out between the sign and the vinyl frame. IT MADE ONE HECKUVA MESS !
Looked like the sign had an afro !
I saved the sign but had to replace the vinyl sign frame. I actually ended up making a frame from 4x4s.
Now ,when I use Gorilla glue I make a pass with the bot about .250" deep . I do this every 6 inches. Then put the gorilla glue in the slots. It allows it to get some air and set up better. If you do have over expansion , you can just lop it off with a pocket knife.
Others may have more ideas, but this has worked well for me in this application.

Ok boys, it would be helpful if some of you would run few easy glue-up tests and post them. I don't believe manufacturers tests. If you gather up scrap HUD, Extira, Plywood, and 2"x4" wood and glue em up. Aften a full day, or over night put one side of each test and give it a tug. You'll find out which works best with which materials.

The best use of Gorilla Glue is with HDU to HDU. I've found it to be a poor adhesive for anything else. Please give this a try and see for yourself. When it's setup, you have a very pourus HDU.

I've found epoxy to be the toughest. Any Brand. Although I prefer Plastic Resin Glue over eposy for gluing up wood boards. It rivals epoxy for stregnth however it's a poor choice when gluing up large flat panels 4'X8's since the interiors can't get enough oxygen to set up and dry.

I look forward to hearing about your personal tests.

Hi all,

Thanks for the info. If anyone can chime in, I'd like to know if anyone has had success making a double sided sign out of:

1. Extira, and sandwiching the two pieces with a sheet of MDO in the middle for strength....or was it even needed?

2. Signfoam, and sandwiching the two pieces with a sheet of MDO in the middle for strength....or was it even needed?

3. Signfoam, and sandwiching the two pieces with a sheet of Extira in the middle for strength....or was it even needed?

The sign is 50" x 24". I will be V-carving the sign as this is what the customer wants. On a side project, I want to try Joe's suggestion of using MDO and pocketing out the letters and inserting cutouts. Seems like a good idea.

Thanks everyone!

Here is what I think in regards to this subject.

Glue ups are same princeple as gluing 2 planks up face to face.(heart to heart, bark to bark)

What I look for is balancing of final product, if additional strenght is required yes add MDO or other at this point I look at it like plywood core is balanced and has odd number of layers balancing each side out.

As per adhesive I would use what works on used combination of materials and per application.

if your going to use gorilla glue on man made stuff you need to add some moisture to it. wipe the two surface's with a damp cloth. the glue needs moisture more then air.

I like to sandwich.

Lately I've been using plain old DOW insulation for the depth, thickness,and MDO or DiBond for the surfaces. The glue is epoxy. Any brand is good.

Textures are very important. On this piece I'll use a hopper gun for a stucco texture. There are lots of attractive textures which are easy to apply and don't require special painting techniques.

There's good money in this kind of work when using regular, non exotic, materials. I could have made these letters from MDO, or Extira but I had some extra PVC scrap.

I'm using less and less HDU or high cost materials.

Hi All,

I know this thread is pretty old - but the scenario has come up again with a new sign. But first....the results of the old sign:

I decided to use Extira for both sides of the sign. I routed channels on the backs of the signs....on up high on one sign and one down low on the other sign. The channels were to accomodate metal brackets that I had a buddy of mine fabricate. One bracket was screwed to one side of the sign, the other bracket was screwed to the back of the other sign. Then the two pieces were glued together. It was a pain and I had one case where a screw "almost" came through the front face.

In the end it came out ok, but I wasn't a big fan of using Extira, and I wansn't really pleased with the mounting method. So......

I have a new sign job I'm working on. Similar scenario but I've decided to use two 1-1/2 inch thick pieces of Signfoam for the double sided sign. This sign is also going to be installed between 2 4x4s in the ground. sign dimensions are about 3.5 ft by 3 ft.

Should I put something between the two pieces of signfoam? What have others done in cases like this? The customer does not want anything above or below the sign, so it's just the 2 4x4s, the sign, and any mounting harware. Your thoughts are apreciated. Thanks.

I think your buddy can help you with a steel internal structure that can double as mounting posts.
Precisionboard has a great blog area where there are plenty of pics. Lots of projects in construction stages using metal as support and mounting structures.