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Tigerseal bond failed
Slimy38 - 14/10/24 at 09:47 AM

I have a bracket that is a bit awkward in shape and location, it's meant to host the VW globe coolant bottle on the bulkhead. The easiest thought was to just use Tiger seal to bond it in place, but after pressing it in place and coming back to it a few hours later, it had fallen down.

Now I have a suspicion that it was simply me not holding it in place strong enough while it sets, but it's obviously made me question the adhesive itself. In particular, the residue on both surfaces just peeled off like rubber, I expected the clean up to be far more challenging. This was a flat surface of aluminium, around 3 square inches, bonded to the aluminium bulkhead.

What could have gone wrong, what do I need to do better for my next job? Apart from holding it in place while the glue goes off?

JAG - 14/10/24 at 10:20 AM

Holding while it sets is always a good idea....

..but how did you prepare the surfaces prior to bonding?

This is the most important step and will have a huge impact on the final bond

nick205 - 14/10/24 at 10:33 AM

I'm not familiar with the mounting bracket shape/design.

But, given the expansion tank will be carrying coolant and therefor a bit of weight, can you not fit it to the bulkhead with a couple of nuts and bolts?

Slimy38 - 14/10/24 at 11:24 AM

quote:
Originally posted by nick205
I'm not familiar with the mounting bracket shape/design.

But, given the expansion tank will be carrying coolant and therefor a bit of weight, can you not fit it to the bulkhead with a couple of nuts and bolts?


I've gone for nuts and bolts now, it was a toss up between bonding and bolting.

Slimy38 - 14/10/24 at 11:27 AM

quote:
Originally posted by JAG
Holding while it sets is always a good idea....

..but how did you prepare the surfaces prior to bonding?

This is the most important step and will have a huge impact on the final bond


Yeah I think that is the key (pun intended). It was brand new aluminium, IE 30 seconds before I glued up I had peeled off the protective sheet. But thinking about it that's just to protect the surface, does it guarantee a grease free surface. I checked the data sheet and it says 'abrasion not required' but it does talk about degreasing.

Sam_68 - 14/10/24 at 02:48 PM

quote:
Originally posted by Slimy38... it's obviously made me question the adhesive itself. In particular, the residue on both surfaces just peeled off like rubber

Obviously, preparation is key (pun also intended), as is temporary support when curing, but also bear in mind that adhesives are always very good in shear but lousy in peel performance... it's just how they work.

It's why Lotus used anti-peel rivets on the Elise chassis bonding, to prevent peel initiating.

Slimy38 - 14/10/24 at 03:37 PM

quote:
Originally posted by Sam_68
quote:
Originally posted by Slimy38... it's obviously made me question the adhesive itself. In particular, the residue on both surfaces just peeled off like rubber

Obviously, preparation is key (pun also intended), as is temporary support when curing, but also bear in mind that adhesives are always very good in shear but lousy in peel performance... it's just how they work.

It's why Lotus used anti-peel rivets on the Elise chassis bonding, to prevent peel initiating.


Aha, good to know. So that's why it came off pretty cleanly, as soon as I rolled an edge up there was no coming back. If the bracket had stayed in place it wouldn't have been able to peel.

jacko - 14/10/24 at 04:49 PM

Haha tiger sealer / pu glue I must have used hundreds if not thousands of tubes .
Before I retired one of the jobs I did was preparing double decker buses for repaint and we stripped all the aluminium panels off
We made new panels and they were glued on with tiger sealer .
Preparing the panels was to sand the back and wash it with panel pipe as we did with the framing
As we fitted each panel we would tape it on for 24 hours
I hope this helps some one
Graham

Slimy38 - 14/10/24 at 05:34 PM

quote:
Originally posted by jacko
Haha tiger sealer / pu glue I must have used hundreds if not thousands of tubes .
Before I retired one of the jobs I did was preparing double decker buses for repaint and we stripped all the aluminium panels off
We made new panels and they were glued on with tiger sealer .
Preparing the panels was to sand the back and wash it with panel pipe as we did with the framing
As we fitted each panel we would tape it on for 24 hours
I hope this helps some one
Graham


Sounds like it's fit for purpose then, just a bit of user error on my part!

russbost - 15/10/24 at 08:33 AM

Tiger seal/Sikaflex/Siroflex etc. all the same basic thing, surface must be absolutely grease/oil/solvent free, but you'll get far better adhesion if it's also keyed with a coarse abrasive - you only have to think about it, abrasion gives probably double the surface are to stick to & also means you are not just sticking in one plane but multiple - I used to use it to glue wheel arches on on the Furore & they stayed attached at some very high speeds! Only time I had one come off was when rust had got under the sur=face from a poorly painted arm.

The other essential is to ensure it's held firmly in place for 24 hours, just holding in place for 5 minuses is useless, in an engine bay, I'd find something I could jam between the engine or other part & the bracket in question, abrade it both sides, clean it, bond it & I guarantee it will still be there 5 years later!n

bi22le - 15/10/24 at 05:44 PM

I would be 3D printing a bracket in ABS.

Sticking stuff like water bottles on doesn't feel very OEM and quite permanent!

Slimy38 - 15/10/24 at 06:01 PM

quote:
Originally posted by bi22le
I would be 3D printing a bracket in ABS.

Sticking stuff like water bottles on doesn't feel very OEM and quite permanent!


It's only the bracket that was stuck, the bottle itself is then screwed to it. I'm using the existing mounting holes as they seem fit for purpose.

And yes, why didn't it occur to me to 3d print one... after a recommendation to use PETG rather than PLA I seem to be finding any excuse to 3d print stuff!

[Edited on 15/10/24 by Slimy38]