@Lola, I was re-reading your post above about some UV cements not working on metal. Lazer Bond seems to work fine on metal, glass and plastic too!
(Some UV cement may not work well with polypropylene or polyethylene plastics apparently.)
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Also, I found another brand of UV cement on Amazon that comes with a 12 gram refill at a very reasonable price. (12 bucks). I may buy some and try it out on other types of larger projects and repairs just to see how well it works. I like the idea of having an alternative to Cyanoacrylate (Super-glue) without the vapors and other hassles such as getting it on your finger tips. Although Visbella bonds almost instantly when UV light is applied they also mention that full cure takes ten hours. I wonder if that fact applies to the other UV cements as well? It would make some sense that the molecular process that is triggered with UV light might continue to unfold as with other chemical hardening polymer adhesives such as epoxy glue.
https://www.amazon.com/gp/B0744K9TRW
More then likely the ones with UV light cure also have some of the heat cure type agent in the prescription, it's important to the manufactures that their product works, regardless, therefore providing the reason for the included light source with the proper wave length to cure the product. Not all heat agents require a high heat source to cure over time. Their are some products that are cured with heat (or both agents) only but they are basically used only by big companies that work on 100's if not 1000's of lenses, they use special heat ovens that are very expensive.
The UV cements have cure times all over the place from short to long and varies a lot by manufacture, strange, but that's the way it is! The biggest enemy of the UV curing agents is the shelf life of the products, they run from about a few months to somewhat over a year, and the time period starts from the day of making the stuff. For example if you bought some the guarantee to you would be from the day you bought it plus how long since it was mixed at the factory, that's a little something they forget to tell people!
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