Epoxies, Adhesives, and Glues
Posted 04 March 2013 - 07:54 PM
In our studio I always tell students not to buy a one-part adhesive for gluing their sculptures together - this is because they are weak and don't make good structural bonds. Sometimes they can be useful when getting two objects fused temporarily, while using a long-cure epoxy. I explain that they want a 2-part epoxy since you have a resin and catalyst to form a chemical bond - which generally forms some of the strongest bonds without welding or fusing the objects with heat. I also explain that the clear epoxies tend to be weaker compared to opaque epoxies, and that the slower it cures the stronger it usually bonds.
We are a big fan of the PC product line and favor PC-7 and PC-11 for critical structural bonds. Usually, the bond is stronger than the clay and when/if you break it there will be clay or glaze stuck to the epoxy proving the clay/glaze breaks first. I just read on the PC website they have a PC Super Epoxy "syringe-type" adhesive that seems legit since it has similar testing strength to the PC7 - I've never seen it on the shelf before but I might have to find some to test. We buy PC products at ACE Hardware - never seen it at any of the big-box Orange/Blue stores.
I've seen students use a plethora of different adhesives and have seen first hand how well some do/don't do what they are purposed for. There are some 2-part "syringe" epoxies seem to hold just OK but usually not so great since they are mostly the clear variety (LocTite brand for example). Things like Gorilla Glue are a joke, not to mention are a PITA in terms of how messy it gets once the glue foams up when reacting with moisture in the air. JB Weld can sometimes work, but it really depends - and the 24hr version is superior in strength. Liquid Nails/construction adhesives don't really work well either unless you're laminating something on a horizontal plane and use a lot of it. I have seen some people have good results with E6000, but the problem with this stuff is the flexibility. 100% silicone works pretty well for sticking to glazed surfaces and is relatively inexpensive - but doesn't apply to every situation. Some students try to come in with Krazy/Super Glue or even hot-glue and I just laugh - chewed bubble gum probably holds better on ceramics.
Side note - I've found one of my preferred "temporary" bonds that can be added to ceramics is "poster putty" or wall tack/museum wax. The stuff works VERY well when placed between the adjoining parts of a piece built in sections and needs to come apart later - works great for eliminating wobbles instead of using shims when the section doesn't quite mate up like you intended. Usually, we'll just roll it in a coil or place pea-size balls where they need to be, and use it like a gasket. I've even held 2-3# ceramic objects on a vertical surface with a marble-size wad of it as a test - held for several days until I removed it (don't recommend for anything you care about falling to the ground ) Can be purchased at any office supplier and is very inexpensive - and can be reused!
Posted 04 March 2013 - 08:39 PM
Posted 04 March 2013 - 11:15 PM
That was then this now-The past 10 years its been (drum roll)
its now 99.9% JB wield the quick set -ace hardwares or most other retails carry them. The slow set is a bit runny and does come in handy when you need to get into cracks but the fast set is about 4 minutes and is my go to most of the time. You mix them on a piece of cardboard ( I use a plastic handle from say a spoon or fork). It sets dark and if you want grey cut it off with a sharp single edge razor for a grey line
but wait theres more-
This stuff has ripped the high fire glaze off of porcelain in a test-I was amazed . I now use it on just about any material.Clay glaze wood metal whatever you need to glue. This is not a flexible glue. It can take some low heat as well.
When its 100% absolutely needs to be strong water proof and never come loose JB wield is the ticket-
Bamboo steamer NOT included
Posted 05 March 2013 - 09:56 AM
It is specifically for ceramic artists. You can paint it or you can get a color kit.
i agree about east valley epoxy. i have even mixed small amounts of stain into the mix so as to adjust the color of the epoxy to the surrounding glazed area. great stuff.