Devcon shelf life

[Sugar]

I just bedded a rifle with some 10110 that we have had for at least 6 maybe 7 years. The hardener had turned a yellowish color but it mixed and set up well.

 

[Preacher]

I just bedded a rifle with some 10110 that we have had for at least 6 maybe 7 years. The hardener had turned a yellowish color but it mixed and set up well.

That was before the government made them change the recipe...
The new stuff is GTG...

 

[Mozella]

Blair I don't use Devcon so I can't directly answer your question.

I use fiberglass resin, along with West marine polyester fiber (number 403 or 404) , and Fiberglass hardener (MEK) Methyl Ethel Ketone.
I mix this as per instruction according to the temperature. Beware fast curing creates lots of heat, blistered surfaces and gas bubbles. Depending on temperature and quantity of hardener used cure can be 1 hour or 24 hours.
Or

West Marine Epoxy Resin, West Marine Polyester Fiber (number 403 or 404), and West Marine Epoxy Hardener (205 (fast) or 206 (slow). I buy the West Marine epoxy resin (105) by the quart or gallon. West Marine sells pump kits for both the resin and hardener, they dispense the correct premeasured amounts of components. Never had a bottle dry up before it was used up.

Either of these products can be supplemented with color pigments to make them match your existing work piece.

Nat Lambeth

Nat: I hope you won't be offended if I chime in here and add a couple of my thoughts to your post. To avoid confusion, it's important to point out that "West Marine" is a large company with stores in most major cities catering to boat owners. They sell all sorts of stuff to boat owners including products marketed under the "West System" name. "West System" is the company started by the Gougeon Brothers and is famous for their various epoxy formulations and related products. There is no connection between the two other than the store sells the epoxy products with a similar sounding name. Confusing? Yes.

The term "fiberglass resin" usually means a polyester resin catalyzed by adding MEK. The proportions aren't critical ; the more MEK the faster the cure. This is the stuff inexpensive "fiberglass" boats are made of, along with some sort of reinforcing material, usually glass fiber. It is not related to the epoxy family other than both products get hard after you mix two parts together. It is inexpensive, but it shrinks much more than typical epoxy formulations and therefore polyester resin is not the ideal rifle bedding material. Yes, it will work, but I wouldn't recommend it. Plus polyester has lower mechanical properties than most epoxies and the low viscosity (much like maple syrup) means you must mix in some sort of viscosity modifier to use it as bedding material.

Devcon 10110 is a popular bedding compound because it is available in reasonably small quantities and the "A" compound has the ideal viscosity for bedding. The price is about $45 to $60 for a one pound kit at the moment and that's enough to do at least two guns. Truth be told, most DIY builders only need enough for one. It's handy, it's all you need, and it's a genuine epoxy with all the advantages of strength and very low shrinkage. Highly recommended.

The Devcon price is just high enough so that some folks will prefer to use JB Weld, which is also available in smaller quantities too. Unfortunately, the viscosity of JB Weld is lower than ideal. Most people will simply use it as is and, as a consequence, some people will discover voids in their bedding the next day. But the wise builder will beg a half a cup of viscosity modifier from a local boat builder. Colloidal silica is the most common modifier and a teaspoon full will thicken up a batch of JB Weld quite nicely. It won't adversely effect the mechanical properties and is a MUCH better approach than letting the JB Weld partially cure before using it. Some pre-prepared fillers, such as the West System 400 series, include various percentages of colloidal silica (as a thickener) and include other fillers selected to suit various situations. I've used JB Weld as a bedding compound, as have many many others, but it's less than ideal, especially without increasing the viscosity with some sort of filler.

Some fillers are designed to bulk up a typical epoxy resin to make it lighter and/or easier to sand when used as a fairing compound. This is not what you want as a bedding compound. Other fillers consist of chopped fibers which reinforce the basic resin to make it stronger, and these kinds of fillers would be good for bedding. If you decide to use a low viscosity, off-the-shelf epoxy resin, like West System 105 resin along with their 205 or 206 hardener, then adding a high density filler like the West System 203 or 204 to achieve the correct viscosity would be a great choice, perhaps with a touch of 206 (colloidal silica) to fine tune the mixture. For example, you might want a thicker mixture for bedding pillars and a less viscous mixture for use under the action. West epoxy has very good mechanical properties and extremely low shrinkage.

The only downside of using West System products is that you need to invest a little bit more money to get started. A quart kit, including resin, hardener, and a pair of dispensing pumps (they eliminate the need to measure) can be had for around $55 bucks. Add 10 to 20 bucks for two or three different high density fillers and you're ready to bed many rifles. Or, if nothing else, you'll have a ready supply of epoxy for doing all sorts of high strength repairs because the unfilled epoxy mixture is such a good adhesive. Once you have the pumps in place and the two cans sitting on your workshop shelf, it's a snap to whip up an ounce of mixed epoxy to fix a broken chair. I've had open cans of West System epoxy with their pumps in place sitting on a shelf for years and I've never had any deterioration in performance. It's great stuff and the most versatile of the various bedding compounds, most of which are a "one trick pony".