Hot glue is convenient and very cheap, but adhesion is not the best and it has a bit of give to it. Rigid epoxy resin is rock solid most of the time, but it can be a lot more expensive per volume.
Is there a middle ground for general use in the UK?
I've seen several good US brands that are priced well over there, but not so much over here in the UK.
Thanks.
EDIT: Clarified the type of epoxy as "rigid"
Flexible (elastic) epoxy is way more expensive than rigid epoxy. Silicone adhesive is about half way between.
Flexible (elastic) epoxy is way more expensive than rigid epoxy. Silicone adhesive is about half way between.
AFAIK Silicone is more flexible and not as strong as hot glue from what I've seen of it and not really in-between the two I mentioned?
Silicone can be a lot of things. I've got some horrifyingly expensive silicone glue sitting around, which is simply un-removable. Yes, you can tear small chunks of it away, but it never seems to lose adhesion to metal or glass surfaces at least.
Also, you should clarify how thick the glued joint is expected to be - will the parts be flat and touching each other, or are you bridging a gap?
There are different adhesives for different purposes. There is not one "do-it-all" adhesive, despite advertising puffery.
What do you want the adhesive to do? Do you want high peel strength? Elasticity? Compressive strength? Fast setting? "Two" part? Self curing (e.g., cures upon exposure to moisture or UV)? Thermal resistance? Thermosetting? Easily removed? Temporary? Pressure sensitive (e.g., duct tape)? And so forth.
Silicone can be a lot of things. I've got some horrifyingly expensive silicone glue sitting around, which is simply un-removable. Yes, you can tear small chunks of it away, but it never seems to lose adhesion to metal or glass surfaces at least.
This is what I had. Think it was 3M. £40 a tube.
There are different adhesives for different purposes. There is not one "do-it-all" adhesive, despite advertising puffery.
What do you want the adhesive to do? Do you want high peel strength? Elasticity? Compressive strength? Fast setting? "Two" part? Self curing (e.g., cures upon exposure to moisture or UV)? Thermal resistance? Thermosetting? Easily removed? Temporary? Pressure sensitive (e.g., duct tape)? And so forth.
Sure, but there are glues that are considered general purpose for most things and thats what I'm asking about.
You're overthinking what I need. The only parameters that I'm bothered about I mentioned in my OP.
Something stronger bonding and more rigid than hot glue, but not necessarily as stiff epoxy resin. A price that is also nearer hot glue per volume than epoxy. Metal & Plastic bonding, not bothered about wood. It wont be used for filling, just bonding.
Maybe to bond a free floating RS232 port to the inside of a project box, or an LED. Maybe to bond a strong magnet to a wheel.
Normally I'd think of stiff epoxy for the job, but it seems quite expensive.
From a very quick Google, E6000 pops up (I've not had a good look at it yet).. But that's a US brand that is more expensive over here.
Maybe to bond a free floating RS232 port to the inside of a project box, or an LED. Maybe to bond a strong magnet to a wheel.
Normally I'd think of stiff epoxy for the job, but it seems quite expensive.
From a very quick Google, E6000 pops up (I've not had a good look at it yet).. But that's a US brand that is more expensive over here.
I use E6000(aka Goop in the USA) quite a bit. There are different formulations of it. Its cure is initiated by solvent evaporation and generally takes 24 h or more. The cured adhesive is MORE flexible than hot melt, but since it cures to a fairly thin layer, that flexibility may not affect you. The thing that I like about E6000 is that its peel strength is very high, even compared to most consumer silicones and hot melts. Surface preparation is minimal compared to epoxies. I have used E6000 to attach pushrods in model airplanes that are subject to vibration and oil. Epoxy can be used, but I prefer E6000 as it flexes just enough, and I have never had it delaminate from what it was attaching. I also use a semi-flexible, filled epoxy, which offers bulk (fills uneven surfaces) when I need that characteristic.
All that being said, I would still consider a hot melt for what you describe doing, but I would get one with a longer working time and less viscous than you seem to imply having. There are also pressure sensitive adhesives (PSA's) that should work well in that application. PSA's can be quite permanent (e.g., automotive trim), but other versions can be easily removed if needed. 3M has medical, automotive, and industrial versions that are hard to beat, but one of its consumer versions for mounting pictures on walls might be something to consider. It is one of the removable versions. The advantage of these latter suggestions is fast setting and less risk of getting the adhesive where you don't want it. E6000 is fairly liquid when first applied.
As above it might be time to consider different hot glue options, they're not that much cheaper than epoxy (I'm seeing epoxy prices of $/unit volume about twice as expensive as hot glue) but much easier to work with. UV curing is good for production but it sounds like you want something for varied uses.
I've been much more impressed with the usefulness of hot glue since I got some 3M 3748Q sticks and a matching high temperature gun. The stuff is basically polypropylene and bonds to a lot of plastics (particularly polyolefins) which are hard to glue. The only downside is that it's also hot enough to make some plastics soften and bend if you apply a lot of glue.
I keep a little box of adhesives :
- 5 minute Araldite
- 24 hr Araldite
- JB Weld
- Devcon Plastic Bonder
- Cheap Cyanoacrylate
That covers mostly anything I want to glue. Araldite is a decent all round general purpose Epoxy adhesive. The Devcon works for most plastics except HDPE & PET. JB Weld is the epoxy version of duct tape.
Araldite and JB Weld are available locally. The Devcon I get from Amazon US. I don't know what's available in the UK of course.
I have some other epoxy elastomers and platinum cured silicone, but they are absolotely application specific.
As above it might be time to consider different hot glue options, they're not that much cheaper than epoxy (I'm seeing epoxy prices of $/unit volume about twice as expensive as hot glue) but much easier to work with. UV curing is good for production but it sounds like you want something for varied uses.
Thanks I'll look into those. I had just assumed there was one type of hot glue / stick. What sort of keywords should I be looking for with these harder setting hot glues?
Maybe to bond a free floating RS232 port to the inside of a project box
You might consider trying some different epoxy putties. While this is not necessarily less expensive than epoxy casting resin, you may be able to achieve better results with less volume of epoxy when doing things like this. Some epoxies are a bit flexible, too. You might experiment with your own fillers/additives if you want something more flexible.
The sticks you can buy in the auto shop are pretty miserable to work with. Sticky mess and short working time. You might want to try some different "sculpting epoxies." Some can be had quite cheap in large quantity. FWIW, the stickiness of the uncured product (or lack thereof) between different brands has never seemed to make a huge difference in the cured adhesion strength, to me. There are some putties that are pretty easy to work with but they still bond great. When heated up they get quite sticky (and fluid, of course)... So maybe the stickiness is there, just "slower" or something. Like different formulations of molasses with slightly different melting temp.
Pratley Wonderfix is a flexible polyurethane 2 part adhesive. cures flexible, and sticks well to most things, aside from things that are typically hard to glue, like PTFE, some nylons, certain PET plastics and the like. Does well on PCB, metals, glass and especially rubber.
Otherwise for a general purpose single part polyurethane sealer try Sika Pro 2 HP, which is available worldwide. Drawbacks are cleaning once cured ( grind it off), it takes a while to cure in thick layers ( oxygen curing) and it will stick to everything around if you get it on by accident. Most common use is to make joins in concrete, and to put piping into ponds and tanks. will cure underwater, but is toxic to fish while curing from the isocyanate given off. Available in black, white and IIRC grey and brown. I use it for plumbing, and have used it to put window glazing in as well. Seal a toilet bowl to a pipe with this and the only way to remove is to put a new bowl in along with the pipe.
Hot glue can be very sticky. But it's often spoilt by cooling on contact with the surface, creating a hard shiny layer that doesn't grab well.
If gluing onto hard surfaces, warm them first, or apply the glue and then hot-air it until it runs properly into the crevices.