I need to glue a couple hundred little aluminum tags to the plastic caps of vials of essential oils and aroma compounds. What method would work best?
The vials come from many different sources. The type of plastic obviously varies, and the sellers never specify the type. Based on industrial and laboratory vendors of empty vials, I can guess that many of them are phenolic or polypropylene. Perhaps melamine and polyethylene also turn up.
I’m thinking the right hot melt glue sticks could be good. The commonest hot melt glue chemistry is optimized for cellulose, for use with paper and cardboard, and I don’t think that’s best, but there are polyolefin and other types of glue stick that might work well. I’m trying to find these for sale.
I also think epoxy might be good.
I bought dozens of empty vials whose caps are specified to be phenolic, and also dozens that are polypropylene, so I can do some experiments.
Any reason not use silicone? I don’t think it would be susceptible to the vial’s contents but it is more easily removable than epoxy. Hot glue will adhere very well to the vials i think if you use the hotter variety (maybe not so much with phenolics) but not as well with the aluminum. Are the tags already made? Could they have a hole in them for a more secure attachment?
Isn’t it more important to mark the actual vials? What happens when you uncap more than one at a time, and you need to get the caps back on the right vials?
Die cutting will be key–cut from one side, then peel ALL couple hundred from the back side. Adhere, then peel off the remaining side. Elsewhere lies madness. Not sure if I described that adequately.
I have this stuff mentioned by Ben Krasnow of Applied Sciences (youtuber) called “Devcon Plastic Welder” that glues everything-- “hard plastic, styrene, acrylic… wood, metal” meant for “dissimilar materials.” It’s a 2-part mix like epoxy, maybe it is epoxy?
You probably know better than I, but in my experience epoxy is a poor choice for most plastics, unless you’re thinking of a special kind. When I use epoxy, it’s usually the “5-minute” fast-cure type, and while it works great for many materials, it’s terrible for most plastics.
When working with a variety of different materials and gluing unlike materials together, contact cement is often a good choice.
Hot melt is the clear winner.
Sticks to almost anything, including “low surface energy” plastics, cheap, easy to apply.
Some of the other suggestions are stronger, but that’s not really a consideration in this application.
They are brittle, for one.
Also, they don’t adhere well to many smooth plastics, especially Polyethylenes or Polypropylenes.
I don’t think this is a particularly demanding application, so almost anything will work to some extent, but hot melt is easy and probably the most reliable.
Yeah, true. I found this is a matter of dosage… one TINY drop of GG is all you need, waaaaay less than you think, and it holds really well once it cures.
Poly-Weld is not as good as claim. It requires treatment of polyethylene/propylene before gluing. The treatment is done with a propane torch. There are primers for applying cyanoacrylate glue to poly. First heard of this on the Dope years back.