Today I started to glue down 2" extruded foam to the plywood on my bench tops using Titebond II yellow wood glue. I placed scraps of 2" foam on top of the foam to protect its surface and weighed it all down with sidewalk pavers.
My question is the following: What is the minimum amount of time that must elapse before I can remove the weight from on top of the foam? In a search of this site, I have seen drying times mentioned of 24-48 hrs. before removing the weight.
Thanks for your help,
Bob
I just use 2 1/5 inch drywall screws with fender washers and don’t use glue. You could do the same and just add a few screws/washers to hold it down. That would allow you to work on it while it’s drying.
Otherwise the time frame you allowed should be more than enough.
Read the lable on the bottle. Double it. Your not using it on wood.
I used 2 1/2" drywall screws with fender washers also, it made it much easier. There was one same module I added later and I glued the foam down with tite bond glue. 24 hrs later it was good to go, you’ll have no problem, just give it 24 hrs.
I usually let mine go at least 48 hours before taking the weights off. Depends partly on the humidity, the plywood can absorb pretty good if it’s dry, but the foam does not. The foam to wood joint dries faster than foam on foam - I stacked 2 layers of foam on my layout. The foam to foam joint takes even longer than 48 hours - 3-4 days is not out of the question, but once it dries, it’s stuck on there. Be patient - I can’t stand to work at just one thign constantly so I don;t complete allt eh benchwork before moving on, that way while I’m waiting for the glue ont he benchwork to dry I can go to a previous section and lay track or whatever. I STILL haven’t finished all my benchwork - my excuse is that with the middle open it’s easier to get in and paint and balalst the main line, before I add the cement complex. My secondary excuse is that I don;t have the cement plant buildings ready anyway.
–Randy
I use the water-activated Gorilla Glue instead. It lasts longer (other glue seems to come loose after a few years).
Per
I used the gorilla glue too. I think it’s suposed to set up within 5 hours as a rule. But I weighted down my foam with small ziplock bags of play sand and just let it set for a week. I was in no hurry to mess with it and wanted to be sure it cured well before I did mess with it.
Oh yes, I forgot to mention that. The Gorilla glue expands a LOT so the foam needs to be kept in place with weights and/or clamps (on boards - not directly on the foam). Overnight drying is all I have given it and that’s enough.
Per
Guys! The OP has already used Titebond II Premium wood glue, not drywall screws and not gorilla glue. Telling him to use a different method really doesn’t help, unless he’s planning a later expansion.
Drying time will really depend on how much air is able to get to your glue. Ordinarily, clamping / weighting for 2 hours is sufficient, but that’s gluing wood together. Since only one side of your layout is wood, doubling the recommended clamping time is a good idea. The key instruction, though, isn’t the clamping / weighting time, it’s the DO NOT STRESS JOINT FOR 24 HRS one. So, you can take the weight off after 4-6 hours, but wait 48 hrs before stressing it (this would include leaning on it or applying plaster cloth or something over it). However, it won’t hurt it to leave the weight on.
I’d like to thank everyone for their input on my question. I decided to use Titebond II glue because it’s relatively cheap and can be bought in quantity, eg., gallons, if you need large amounts. It is fluid enough to spread out between the plywood and foam surfaces when weight is applied. I apply it directly from the bottle in a zig-zag pattern so air can potentially get into it from the outer edges of the plywood and foam board. I allow the applied weight to spread it out between the plywood and foam surfaces. I do not spread it out before placing the foam board on the plywood.
Based on your input, I think I’ll let the glue dry at least 24 hours before I remove the weights and do nothing with the foam for at least 48 hours to preclude the possibility that the foam will be displaced. I’m not in a big hurry on this, so I think it will not hurt to go longer rather than shorter with the weights in place.
Thanks again,
Bob