dickb

Is epoxy really needed

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I make a few knives from time to time. Mostly hidden tang. 
The shelf life of most epoxies (or maybe after opening) is pretty short and I always seem to be buying another while three quarters of the last one goes in the trash.   I have researched cutlers resin and that seems like an easy solution, but I may have come up with an easier one. 

While in the process of burning in the tang of a new knife, I noticed that after pushing the hot tang into the handle I had to put the blade into a vice and use a hammer to get the handle off. I  use well aged hickory for the handles. Very tough and stable.  

So I am going to skip using any adhesive and see how it stands up. I can always go back and use some kind of adhesive. As an alternative I may just let the end of the tang protrude through the handle and cleat it.  I have a few old Chinese cleavers and they are all made with  cleated  tangs.
Some are over fifty years old and still absolutely solid. The better ones have a small washer and the back of the tang goes through it and is peened in place.

 

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Store epoxy in a dark place, no sunlight nor fluorescent lights. Buy one hour and not 5 minutes. 

If your epoxy is crystallizign it is not bad. You can put in the microway and turn good again. 

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Try a different or longer setting epoxy.  Try inletting the tang with a broach instead of burning it in.  Or, as you say, try a butt cap and peening over the tang. If your knife is mechanically fastened, great.  Even if it is, epoxy's not a bad idea.

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In answer to your initial question, no it is not necessary.  Burning the tang in is the way it has been done, probably since the start of knife making.  I know of some professional makers in the US that burn in the tang (and it's my understanding that many of the masters in Japan still do it that way).

The benefits of epoxy is extra insurance and it can help seal the slot so water can't seep in.  I've had the same problem in the past, and instead of buying large amounts of epoxies like West Systems g-flex, get some 30-60 min epoxy at your local hardware store that come in the tubes with the plungers, they last a while when stored properly and aren't as expensive, so if it does you're only out $3-4.

 

as always

peace and love

billyO

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No, epoxy isn't necessary.  Only thing I use it for is a moister seal.  With few exceptions I always use a mechanical lock to hold the handle on.  That said, I normally use Acraglass and it last me a year or so and haven't had it go bad yet.  Am currently trying Gflex out so we'll see.

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Store opened epoxy in the refrigerator and it'll last months at least. G flex recommends refrigerating ANY opened containers to preserve it for 6+ months. We stored ALL the rubbers and resins in a refrigerated room and none were RTV (Room Temperature Vulcanizing) or Setting, RTS. Still any of them will set up and eventually cure. Resins will set without the catalyst and if you have the time to wait they'll set strongest without catalyzing. 

The longer the set time (not to be confused with the cure time) the stronger the epoxy. If you want fast set check out the UV setting single component epoxies. They're not great for strength but if you need to repair the horn on the glass unicorn they're the way to go. It sets as soon as you shine the UV light on it, seconds.

There are lots of different polymerizing resins available, most common, polyester, epoxy and phenolic. It's not typical to find single component resins in retail outlets but some are being made available. Cactus Juice is a single component heat setting impregnation epoxy.

Single component resins just mean the resin and hardener are already mixed with an inhibitor. The desired setting agent can be: heat, UV, oxy, vacuum, etc. The hole patching kits on the space station use a vacuum setting resin though I don't know what kind. When the thinner that lets it penetrate easily / inhibitor evaporates out the resin polymerizes and sets, though cure time can be days. Next experiment I'll try curing it in the toaster oven to speed evaporating the inhibitor. Freeze drying won't work, wrong volatile. The local plastics supplier recommended denatured alcohol. CAC plastics actually carries West Systems resins on the shelf! G flex is available about 15 minute drive from here, just the other side of the Parks Highway from our PO box. 

I never thought working in a rubber plant 48 years ago would come in handy, there really IS no useless information. Funny thing life.

Frosty The Lucky.

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"Toaster Oven and the Volatiles" would be a good name for a band.

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As long as the epoxy is hidden and not visible I will use it. Have problems with my heel axes to attach them to the wooden knot handles (shrinking). As long as I’m not able to extract (get) birch resin.

DSC00342.JPG

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4 hours ago, ThomasPowers said:

Toaster Oven and Volatiles?

Yeah, it shouldn't terribly dangerous driving off the residue in the wood so the concentration will be very low.  If it turns out to be another example of how wrong I can be the corner I use for this kind of exercise is clear of flammables and easily damaged things and I have a sheet of plywood I can stand as a scatter shield.

The solvent is denatured alcohol, what's trapped internally should be minimal.

Frosty The Lucky.

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5 hours ago, Frosty said:

Store opened epoxy in the refrigerator and it'll last months at least.

Hi Frosty, two part epoxy should be stored between 18 C and 30 C ... whats that ... 65 and 90 F

Refrigeration helps store a whole lot of glues and resins but not two part epoxy glue unfortunately. 

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7 minutes ago, Marc1 said:

Hi Frosty, two part epoxy should be stored between 18 C and 30 C ... whats that ... 65 and 90 F

Refrigeration helps store a whole lot of glues and resins but not two part epoxy glue unfortunately. 

Refrigerate after opening is the manufacturer's recommendation where West Systems 2 part epoxies are concerned and was how General Connectors, the company I worked for, stored ALL their 2 part and heat cure resins and rubber. 3 main types of rubber impregnated fiberglass we used were: Neoprene, Silicone and Chloroprene.  I believe the cold room was kept at 40 f. AND DARK dim red lights and not many! Everything was marked in large white letters and only a couple of us were allowed to stock. 

Cactus Juice recommends refrigerate after opening but it's a single component heat cure impregnation epoxy.

However I don't bother with Devcon adhesive epoxy, I use it till it hardens in the tube and toss it, it keeps at room or shop temp whatever those happen to be sometimes for years. 

What you describe is considerably different than I'm seeing here. Resins are formulated by their manufacturers and there's a lot of room for difference. Could well be what we use isn't even available your side of the planet and vise versa. However I'll be first to admit I'm close to 50 years out of date where experience is concerned. I've just been reading various manufacturer's info pages since I decided to finish the seax Theo sent me and I have all this Myrtle wood I've had for I don't know how long that needs stabilizing. 

I could be way wrong except where the West Systems pages say about storing their products and they don't offer single component resins. On our level anyway.

Frosty The Lucky.

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I agree that epoxide and their co-reactant are numerous and formulated for different purposes. However a quick search using the string " Storage of epoxy resin" brings up recommendation from different manufacturers including west system and they all say the same thing, almost a cut and paste of the text below. It is possible that there are a lot of resin that will store better in 5 C, that is in the fridge, I have a few marine caulking materials in the fridge that are still usable after 2 years. Two parts epoxy is not one of them apparently. Lower temperatures make the resin crystallise. This can be reverted with heat or in the microway oven but I am sure it does not make it any better.  

Store Epoxy resins and hardeners at room temperature (65°F- 85°F) in sealed containers until shortly before use. As with many high-performance epoxy resins, repeated exposure to low temperatures during storage (<55°F) may cause the resin to crystallize. Be aware that containers placed near outside walls or on the floor will often be at a lower temperature than the ambient conditions.

If crystallization occurs, warm the resin to 125°F for 8 hours and stir to dissolve crystals. Hardeners may form carbamation when exposed to CO2 and moisture in the atmosphere for extended periods of time. Prevent carbamation by keeping containers sealed and pump reservoirs covered until immediately prior to processing.

 

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I like epoxy in my handles (hidden tangs). First for keeping moisture out. I found that even a tiny gap will retain enough water to create a major rust issue.

Another reason is to strengthen the wood - being pretty, it may not be strong, or the grains may not run straight and lengthwise. The epoxy and the tang greatly strengthen the handle.

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21 hours ago, Hans Richter said:

As long as the epoxy is hidden and not visible I will use it. Have problems with my heel axes to attach them to the wooden knot handles (shrinking). As long as I’m not able to extract (get) birch resin.

Quote trimmed

You just happen to have a replica of the Venus of Willendorf on your anvil? lol

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You mean you don't?!?!?!  How very odd We have folks here forging skulls, moai, elephants, fish, birds why not a *seriously* historic piece? (I remember if from a previous casting pic---but you don't need to work harden sculpture like a bronze blade or palstave)

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Right you are Marc 1. Room temperature storage is correct. Now I have to hunt down what I bought that wants refrigeration after opening.  To further dis my memory I called Ruben last night, an old school friend who worked for General Connectors too. Dad got us both jobs there. Anyway, he pointed out almost everything we used was heat cured, we used so little 2 part they bought it in gallon cans rather than 55 gl. drums like other resins. 

Thanks for sticking with it Marc, I was wrong. Well done.  :)

Frosty The Lucky.

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