Gluing two sheets of 1/4" plywood together ?

[Bruce King]

Don’t use the fast set glue, it will start to glob up before you can get an even spread. Make sure to have plenty at the edges.

[glenn bradley]

Glenn that's a Pec Blem 4" double square in your last photo and I claim my $5.

I have used just a Titebond "glue web" to marry two sheet of plywood in the past with no issues, but it was always for shop fixtures, not for clients.

$5 to Mark for the win!

[Alan Lightstone]

Full surface glue layer, flat reference surface, clamp with cauls or evenly distributed weight. You don't mention size but, I have laminated plywood to MDF for work surfaces using a roller to quickly distribute the glue and barbell plates for distributed weight clamping. Make one sheet to your final dimensions, laminate an oversized second sheet, use the first sheet as a template to flush the added sheet.

I like Glenn's method. Plus you get your workout, so think of the time you save not going to the gym.

Personally, I think I'd use epoxy, or something like Ultra-CAT™ PPR Veneer Glue (a high-solid content, pre-catalyzed powdered resin veneer glue with an extra long open time) and put it in a vacuum bag over a good reference surface of MDF. That's how I've done it, but fortunately never with a full sheet of plywood. That will give you plenty of open time, then I keep it in the vacuum press overnight. Of course, you have to have the veneer press / vacuum / bags etc...

[johnny means]

Unless this part is going to be stressed in some way, you don't need much glue. I just run a bead around the perimeter and a couple of Xs to hold the center together. Less glue will require much less clamping force. Too much glue causes the glue to flow to areas of less pressure, leaving thick areas. This is even an issue with a vacuum press maiking 14 pounds on every square inch.

[Ole Anderson]

I would use water based contact cement on both surfaces and use some 4-6 mil poly as a slip sheet. Then roll the heck out of it with a J roller on a flat surface. If you can't vacuum bag with PVA glue.

[roger wiegand]

I did some lamination with (solvent-based) contact cement when I was first building out my first permanent shop ~30 years ago. It has now failed and delaminating and I'm having to re-make those tabletops and fixtures. (actually it failed more than decade ago and I've been slapping bandaids on it since then until I had time to re-make things). This is consistent with my observation of how long in general it takes for the Formica to fall off of old kitchen counters. So contact cement is fine for temporary things, or if you're old enough that it will outlast you. The joints in those same tables done with titebond are solid as a rock.

Is the water-based stuff a lot better than the old solvent-based adhesive? It sure stank.

[Kevin McCluney]

Do yourself a favor and buy an inexpensive brayer to spread the glue. Get one with a metal axle versus plastic as the plastic will wear out quickly when rolling a large surface.