Adhesive for non-porous surfaces

car body filler/liquid metal

Rough up both surfaces.

I think more details of the particular application would help people offer more specific advice.

A stainless steel benchtop has partially separated from its wooden frame, as a result of being buffed (and heating up, I presume). I want to stick it down again. I suppose I need to determine what adhesive was used initially. I'm guessing it was epoxy, but I don't know how to make sure of this. Someone (the buffer-duffer) has already tried to stick it back together with contact adhesive, but apparently didn't clamp it properly and achieved only a small area of contact, which failed to hold. As a result there is already contact adhesive on the surfaces, which predisposes me to using that option (but with proper clamping), because I'm not sure what else will stick to it and it is such a bugger to clean off (limited access into the gap). Removing the frame completely first is an option but a very unappealing one, because of the way the stainless steel sheet wraps around on two edges, creating, with the glue, a strong bond.

Thanks Gib. I was already going to suggest contact adhesive, but your additional details make it even more likely to be the best solution.

However, I wonder if anyone with experience of foaming polyurethane adhesive could comment on its suitability? I have only started using it comparatively recently, but it does appear to fit the task of sticking stainless steel to timber. The foaming aspect means that it will fill small gaps ensuring a better bond.

As I am sure you realise, the main difficulty with contact adhesive would be maintaining close contact over quite a large area while the contact adhesive sets.

The foaming polyurethane adhesive I use is here:

Note that it will now be sticking to the original adhesive with a coating of dried contact adhesive, not to timber.

Yes, for this I will need quite a few clamps, and a rig with a solid plank of timber, e.g. 4x2.

I'm not sure that this will work when both surfaces are non-porous, since it is moisture-curing.

I don't think clamping will do much for contact adhesive. The idea is to let both surfaces dry before they make contact.

There's more than enough moisture in the atmosphere, I think. The application information suggests moistening only porous surfaces.

If I was doing the job, that's what I would use. But I'm no expert - I have only been using this adhesive for a short time.

Others on here know far more about it than I do.

There's moisture in the atmosphere, of course, but it has to get to the glue. If one substrate is porous that provides a pathway, but if both are non-porous the moisture has to diffuse through the thin layer of glue. I experimented with a product called Liquid Nails, commonly used for metals and wood. After a couple of days when I removed the clamp it opened up and the glue was still wet.

Yes, the surfaces must be brought into contact. That's what the clamps are for, to ensure that a good contact area is created. The guys who tried to fix it before clearly didn't use clamps, or not carefully, and I'm stuck with the results of that. This bench is about 3m long, and the metal needs to be forced into contact with the frame over that distance. At the moment there is a gap ranging from 3 cm to zero along the join.

The foaming PU adhesive should work fine in this application. I suggest you spray a very light mist of water into the joint before applying the adhesive then clamp the joint firmly for at least 24 hours..

I'm surprised that no one has mentioned expanding polystyrene foam in a can. It stuck a canoe builder to his canoe :-)

Dave

er, should that be polyurethane? PS is weak as a foam and can be dissolved by most organic solvents.

The expanding foam is polyurethane, ITYF.

And several of us have suggested foaming polyurethane adhesive, as you would have realised had you read the thread before posting.

And the cobbler stuck to his last - I wonder what he used?

The expanding foam could be a bit tricky to apply in my situation. I'm currently testing the philosopher's suggestion (or something like it) - what we call builder's bog, a polyester resin + hardener. So far it seems to be working on a small test patch.

Someone has already suggested polyurethane adhesive. Considering the two materials you are bonding this is more likely to work in that it retains a little flexibility when cured.

Why not give a manufacturer a ring and ask if they recommend it for bonding sheet stainless steel to a set resin or something like formica? I used a lot of adhesives and sealants when I was working and often rang the tech support people for advice where the situation was outside the normal. I always found them very helpful. Loctite people especially. They were the ones who told me how to bond PTFE to metal. Almost impossible with normal adhesives.

You can't leave it there! How do you do that?

(No - I don't have a need - just how to bond detached PTFE 'feet' back onto plastic mouse shells.)

Primers on both surfaces allowed to dry and then a loctite adhesive applied. Sorry I can't recall the numbers of the adhesives and primers after 14 years. The primer left a green tint so it probably had a copper content. That's about all I can remember.

Roughen the surface and try cyanoacrylate gel and hardener

Did a search for the stuff but best I could come up with is this where they mention a primer for PTFE bonding