Epoxy question

[mnwildpunk]

I read that a lot of guys use epoxy for glue. I went to the hardware store and was overwhelmed by the choices. Two part epoxy, epoxy resin epoxy adhesive, quick set and on and on and on. which type do you use?

[Ace-Garageguy]

All of them have their places, depending on what you need to do. All true epoxies worth using will be two-part, and will require mixing. And in general, the stronger ones will take longer to cure, and will require more accurate mixing. I've been heavily immersed in epoxy composites technology since 1984, and I'll tell you true.

The 5-minute stuff has low strength, really, but it's good for temporary holding, fixturing, window glass (it works but I prefer PVA for that) and other jobs that you need done quickly. It will usually scrape off without leaving much residue, as it has no solvents to penetrate the plastic.

JB Weld is a widely known epoxy paste that has remarkable strength, holding power and temperature resistance for a low-end hardware-store product. Most of the other epoxy products on hang-tags do what they say they'll do, so just read the directions and imagine the possibilities. Most epoxies have a shelf life of a year or so, so try to avoid the dusty packages on the "sale" table.

Flying RC model airplane builders have hobby-shop choices of quick-set 5 minute, 15 minute and 30 minute, in general. Again, the longer the stuff takes to set and cure, the stronger it will be. So, 30 minute is MUCH stronger than 5 minute.

And though a lot of "experts" will tell you you can be sloppy mixing, that's just bull. For maximum performance of ANY epoxy product, try to mix it as accurately as possible. Adding more hardener to epoxy will make it weak, and sometimes it won't cure at all.

If you want to get into higher strength for reasonable cost, the West 105 epoxy resin system works well and is widely available. Unlike most of the 1:1 junk epoxies, it's the real deal, and the mix ratio is 5:1. You need to be pretty accurate with the stuff. You can make an easy-sanding, super sticking, very strong white bondo-like paste with it.

Aviation structural composite epoxies (also used in carbon race-car parts, etc) are extremely sensitive to mix-ratios (you have to use a gram-scale), temperature, handling, and elevated temperature post-cures. They can also cost several hundred $$ per gallon, but what you can do with them is really amazing.

In general, I use ordinary liquid glues for most work, and only use epoxies for mold-making and parts reproduction, or where exceptional strength is required...like reinforcing the insides of joints on pillars for chopped-tops, or major body surgery.

Edited June 4, 2013 by Ace-Garageguy

[mnwildpunk]

Once again bill you amaze me! is there anything you don't know?

[mnwildpunk]

Mainly I'm looking for something that holds windows in better then white glue or testors canopy glue

[Ace-Garageguy]

Once again bill you amaze me! is there anything you don't know?

That's kind, but there's WAY more I DON'T know than what I do.

[mnwildpunk]

Fooled me

[High octane]

I use Devcon 5-minute epoxy which comes in two parts and it is great as it dries clear and bonds strong. I also like it as I can glue wires, guitar string, and different material to plastic. I've been using it for years and sure it's a bit pricey and there's a lot of waste, but when I take my models to a club meeting, contest, or model show, I don't have to bring a repair kit.

[VW Dave]

Mainly I'm looking for something that holds windows in better then white glue or testors canopy glue

Micro Krystal Kleer by MicroScale is my favorite for that job, as epoxy thins out while curing and can bleed around window parts.

For epoxy, I use the Permatex or Devcon 5-minute stuff in the handy-dandy syringe applicator(mostly because I hate measuring/guesstimating with the 2-bottle versions). Semi-opaque plastic medicine dispensing cups make for great mixing vessels, and they are reusable....after the leftover epoxy sets up, simply flex the cup a couple different ways and the solid mass of surplus epoxy pretty much pops right out.