Glue underlayment to concrete: how long does it take to cure?

Question

This question is related to another question I posted earlier.

I glued FloorMuffler underlayment to concrete using Roberts Engineered Wood Flooring Adhesive. The instructions say "open time up to 20 minutes" and "install hardwood while the glue is still fresh, do not allow it to skin-over". I do realize that underlayment material is non-porous and installation method may differ from hardwood flooring, but since there were no specific instructions, I proceeded according to the instructions on the can of glue. I probably gave it 10 minutes of open time before I rolled underlayment on top of freshly applied glue. There was a lot of trapped air that caused bubbles. I pierced them and pressed the air out. Next morning I was ready to install the floor, but I noticed the glue under the underlayment is still fresh. It cured around the edges, but it is completely fresh otherwise. What did I do wrong? What are my options now?

Update: The underlayment was installed on Wednesday. Sunday night I checked, and there are still some pockets of uncured glue. I am worried that the glue might never set at all. Still looking for a solution.

Answer 1

On its website it says 8-10 hours. However it is not for the application you used it for. It is for gluing wood to things. Not for gluing foam/felt/whatever to concrete. Your underlayment has basically formed a bubble underneath. The wood glue needs a lot of air to dry - hence wood glue there will usually be a lot of air available. Now that the outside have dried quicker of course, now the inside is in the trapped little bubble with no chance at getting good air. It will eventually dry but this depends on the material and how dense/thick the concrete is. Also you may want to just remove and use the right glue - which will probably last longer - but that is up to you. This could take 2-5 days to dry and since the glue was made for wood it may not bond right.