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OT: Not satisfied with available adhesives, especially super glue.

rons

Diamond
Joined
Mar 5, 2009
Location
California, USA
This not as off topic as I would think. If a machine repair has an encounter with super-glue or contact cement the result is not so great.

Another OT item is plastic pieces on you name it that break off, maybe like the tabs on a cover plate. Gluing with solvent plastic cement is
the only thing that works. I've tried super-glue, white epoxy, clear epoxy, etc. All that stuff never really works. And I went to Home Depot
today and there was just Gorilla glue and super-glue. Construction adhesive in big tubes.

Another OT item is gluing metal like aluminum to plastic. Super-glue on AL to AL works. Solvent cement works on plastic to plastic.
What about AL to plastic. Maybe super-glue works but I don't trust it.

Or maybe my opinion on super-glue is based on data like having a tube around for a few years and then using it. Is the right thing to do is
just buy it in those small tubes when you need it. Then if it goes beyond a number of weeks the glue degrades and is not as effective?
 
The thing about glue/adhesives is there is a reason why there are a lot of different ones out there. In spite of the manufacturer's claims, each one is good for some uses and you need to choose the correct one for the job at hand.

The other thing is you must properly prepare the items being joined and use the proper technique when applying them.

So, super glue is great for joining two surfaces that will have VERY SMALL gap between them. It does NOT fill a gap over a very few thousandths of an inch and really is at ti's best if the gap is less than one thousandth. So it is great if you are repairing a china cup that broke because the pieces fit together with almost no gap. But if you just take two pieces of metal that have never been one and try to glue them together with super glue, it probably will not work. They make a gel style super glue, but it is not much better. This information did not come from any instructions on the super glue bottles, it is from the school of hard knocks.

As for storage, I have used super glue vials that had been opened over a year ago and had excellent results. Contrary to some advise I like to store the open vials with their caps tightly screwed on and in a vertical position with the open end UP. That keeps the air from getting in and the super glue from leaking out. I use prescription medicine bottles for this. (I an in my 70s and have a lot of empty prescription bottles that I use for many storage situations in the shop.)

As mentioned above, JBWeld is quite good. It is my go-to adhesive when I need a strong joint. But I do use other adhesives. I buy the five minute epoxy in the large size bottles and use it often. Contact adhesive has it's uses. So do wood glues. You just have to choose the correct one for the job. I have over two dozen different types of glue and adhesives in my shop and still need to buy a different one for some jobs from time to time.
 
2 of my favorites are Goop and super glue and baking soda.
There are several different flavors of Goop, but I can’t tell the difference in them. This stuff really bonds hard to repair plastics.
The super glue and baking soda works good for fine detailed work and you can build it up in layers. It’s a almost instant repair and you can make it look quite nice.
 
Also, remember that some plastics just "cannot be glued". SOme of the waxy-feeling "engineering plastics" will not accept any glue at all, it just cannot adhere. Those are probably best "plastic welded", assuming they are thermoplastic material, which most are.

You have named the glues which I find LEAST useful.

Superglue is not super for most things. One fault it has is brittleness. They used to show a drop holding a heavy weight, a car, or a heavy man, but the bond between the two small blocks of metal could be broken by tapping with a hammer.

The various epoxies are better, but often not on plastic. They usually do better on steel, but may not stick well to brass or aluminum.

For plastics, and many otehr things, the closest thing to a "universal" glue is stuff called "E6000". It seems to do a good job on a lot of things. But even it will not work on the waxy plastics. The big box stores generally have it where the super glue and epoxy is. You just need to look hard to find it.
 
Have used an IR (infrared) cure adhesive a few times on some small repairs.

Seemed to work quite well. There are various small kits the one I used was marked "Bondic". Suspect it's a super glue like product which was more gel like which allowed a build up reinforce area on plastic and aluminum.

EDIT. It's "UV" not "IR"
 
Also, remember that some plastics just "cannot be glued". SOme of the waxy-feeling "engineering plastics" will not accept any glue at all, it just cannot adhere. Those are probably best "plastic welded", assuming they are thermoplastic material, which most are.

You have named the glues which I find LEAST useful.

Superglue is not super for most things. One fault it has is brittleness. They used to show a drop holding a heavy weight, a car, or a heavy man, but the bond between the two small blocks of metal could be broken by tapping with a hammer.

The various epoxies are better, but often not on plastic. They usually do better on steel, but may not stick well to brass or aluminum.

For plastics, and many otehr things, the closest thing to a "universal" glue is stuff called "E6000". It seems to do a good job on a lot of things. But even it will not work on the waxy plastics. The big box stores generally have it where the super glue and epoxy is. You just need to look hard to find it.

The two resins you refer to are polyethylene and polypropylene.

Each of the adhesives has their good points and drawbacks. "Superglue" does not do well with wet applications. Silicones (RTV) are advertised as being adhesives, but they are really sealants. Epoxies are a good general adhesives, but like all adhesives, require proper surface preparation to be effective. Further, not all epoxies are equal, some do better than others for the same task. Manufacturers used to supply extensive application data for their products but these are seldom seen today. Cut and try seems to be the best, but as stated by the OP, least satisfactory guide.

I would suggest to people wanting more detailed data to search the internet.

Tom
 
Contact a specialty adhesives manufacturer for recommendations.

epotek.com or masterbond.com Beware, they are proud of their products and price them accordingly.
They are worth it.
 
Polyethylene and polypropylene are indeed members of that "waxy" family of plastics, but there are newer types.

Some of the specialty plastics engineered for high strength and impact resistance, etc are also in that class. Whatever their actual chemical composition, they have the same property of being "un-gluable", and generally unrepairable, unless they can be "plastic welded".

Many /most thermoplastics can be "heat-welded", and many also can be "solvent welded". Those approaches are usually best if possible, as they do not rely on a glue-bond to the surface of the plastic.

With thermo-set plastics, such as the familiar Bakelite, you are stuck with a "glue-bond" approach, since the plastic is not meltable, and generally does not respond to solvents. Epoxy may be the best product for many of them.

The problem with glues is that the bond is nearly always considerably weaker than the original plastic. That is why the "plastic welding" technique is usually best if possible, since it to a great extent replicates the original solid plastic.
 
Household Goop, Shoe Goo, and E6000 are the same thing, just packaged differently, and sometimes colored for their intended use.

All are really good for most things, especially when you need some flexibility in the joint.
 
Store super glue upright in the refrigerator. Mine is around 13 years old and still works fine when I need it, I like Zap brand. Cyanoacrylate adhesives have their uses but toughness and durability are not their strong points.

Since you say you tried white and clear epoxy like that means anything tells me you don't have a clue. What it sounds like is you want a structural adhesive, either epoxy or urethane. My go-to all-purpose adhesive is MetlWeld by Systemthree, next best but in much larger containers is 3M, but I tossed the cans long ago so I don't remember the numbers. The downside to MetlWeld is the resin will separate after a year or two and you need to mix it before use. Both are marine grade so after curing water doesn't affect them. Either work much better when weighed out to get the mix exact. I have a scale with .01 gram resolution that I use. Ever since I started using the scale to measure the epoxy out the cures have been far more consistent, no comparison to mixing by volume. I have tried some Devcon and JBweld epoxies but find Devcon to be ok and JBweld to be garbage, just my experience.

Don't forget Nylon and Acetal resins as nearly impossible to glue to. Pretty much any resin that is resistant to oils and solvents will be resistant to glueing to. If you flat have to then burn the surfaces you want to glue to with a torch. Once the resin is degraded then you can glue to it.

Don't forget permanent thread lockers for glueing metals together, they really work well with the correct joints.

As others have mentioned make sure the surfaces to be bonded are properly prepped and clean. For metals this includes removing the oxide layer right before bonding.

Here is a link to 3Ms info on their structural adhesives, lots of good info.
 
Industrial epoxies are orders of magnitude better than consumer grade. I have some Araldite 2013 that I use when stuff needs to be really stuck fast. I tried to glue turcite with regular diy store epoxy - peeled off like taking the foil lid off a carton. Used this 2013 and it stuck down solid.

Last thing I stuck with it was a new tyre onto an electric pallet truck wheel hub. Replacement wheels were out of stock so I found a large ally-centred caster, turned the middle out of and glued it to the old wheel.
 
IMO, if you're unhappy with epoxies on suitable substrates, it's not the epoxy but the preparation. I find most of the advice, even from the manufacturers, is either impractical (dichromate and chemical etching) or ineffective (wiping with solvents). Rough the surface and clean it with something like Alconox, Ajax or Comet. Rinse and don't touch it with anything. If water doesn't wet the surface, it's not clean. If you wipe with solvent after that, you'll likely find that the surface no longer passes the wetting test. Vapor degreasing worked well but we mostly can't do that anymore. For plastics, if you can possibly do a plasma etch, it helps immensely. Even a Model T spark coil could be used. To better understand bonding, look up surface energy.
 
I used some Weld-On #16 that was over 25 years old. The setup time was long enough to get everything lined up. All this for a HP line printer paper movement part.
It could have been designed stronger but it wasn't. It's a 22" x 22" foot print and 20" tall. Holds two 500 paper reams and I use it to print manuals and books.
Makes me think about all the good equipment that gets scrapped just because of a poorly designed point in a inexpensive part.
 
I will see about that. Isn't that liquid sold in 1 gallon cans in the paint aisle?


it's available in quarts.
I use a squeeze bottle with a needle to deliver small amounts of mek on the seams.
The platic is assembled first and the needle run along the edge of the seem.
it's fused in seconds..


I learned this long ago from a friend who owned a plastic injection mold business.
 
methylene chloride for polycarbonate

Tom
And it will give you a very trippy high!!! Door jambs will jump out and hit you as you walk by them. A place I worked at used to buy it in 55 gallon drums.

PS, referring to epoxies as all the same is like referring to metals as all the same.
 








 
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