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I’m putting a sheet of 2-sided melamine particle board (which matches my desk) to a sheet of plywood (for strength) to build an electronics workbench. To do this, I’ve bought a construction adhesive which promises a bond strength of 20 lbs / sf.

To clamp the two sheets together, I will be using screws in an 8-inch matrix. The screws won’t be removed after, I will just leave them. I’ve pre-drilled the holes and placed screws in for speed. I plan to tighten the screws in from center outward, so that any excess adhesive has somewhere to exit.

But I’ve never used construction adhesive. I have absolutely no idea how much to use. The container says “coverage: approx 30ft using a 1/4” bead”, which I’m sure I’m misinterpreting.

I think waves make the most sense, but how far apart should they be?

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  • If you're screwing it together with a screw every 8" to provide clamping (screws are perfectly good clamps), why are you also glueing? Are you planning to do something on an electronics workbench that is so violent that you don't think that many screws would provide sufficient gripping force on their own? (Yeah, I get that it's too late now - your comments on Solar Mike's answer indicate you've already glued...) – FreeMan Jun 10 '20 at 12:18
  • It was a bit of a “guess it can’t hurt” thing. – Rob de Jonge Jun 10 '20 at 12:19
  • Belt, suspenders, duck tape & staples, eh? :) – FreeMan Jun 10 '20 at 12:21
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    And a paperclip, just in case! – Rob de Jonge Jun 10 '20 at 12:22
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I would run the adhesive bead 1” from the edge and then fill in with lines or waves (shape won’t matter) about 3 or 4” apart.

When putting together I would hold the edges open by 1/8” and work out from the centre as you plan.

You could get a similar result by working from one end along the length tightening from the centre out to the sides and removing spacers as you go - centre sag won’t be an issue as long as you get reasonable clamping. Putting bricks on the surface will help but make sure the support prevents bending.

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  • Thanks for the comment. Learned a lesson by not testing the adhesive first. Started laying the adhesive as per your instructions, but it barely squeezed out of the container, must have started drying and thus no flow when pressure applied. So there is now a tiny but discernible happens between the boards. I’ve loaded as much weight on it as I could find and will leave it to sit for the prescribed 48 hours. – Rob de Jonge Jun 10 '20 at 5:00
  • Well, I would have used a "contact" adhesive - one that is applied to both parts then allowed to "dry" for 5 minutes, this would allow positioning and progress as I laid out above. Also a contact adhesive can be put on with a brush or roller. – Solar Mike Jun 10 '20 at 5:07
  • I’m a n00b and this was the suggestion given elsewhere on the forum. Oh well, lessons learned! – Rob de Jonge Jun 10 '20 at 5:08
  • Don't panic, it will, in all probability, turn out fine. The most important factor is the preparation of the surface - clean, dust free and not lumpy... – Solar Mike Jun 10 '20 at 5:10
  • Yeah it was prepped well. No dust and the melamine side was cleared with alcohol for extra clean. The panels are mostly ok, except one corner they remain a tiny bit off of each other. Will see how it turns out I guess! – Rob de Jonge Jun 10 '20 at 5:14

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