Epoxy for Hammer Handles?

[JHCC]

I just ran across an ad from Warwood Tool offering a two-part epoxy for attaching hammer handles to their heads. Here are the specs:

Quote

A room temperature cured, medium viscosity, two-component epoxy designed to bond handles to tool heads effortlessly. High tensile and lap shear strengths and the recommended epoxy adhesive to be used with Warwood Tool Fiberglass Handles. 

Includes:

• 2 x 1oz bottles

• 1 x Mixing Stick

• 1 x 6" SIKA Tape

Typical uses: Recommended as a tooling compound for bonding striking tools such as hammers, axes and sledge hammers.
Bonds: Metal, wood and fiberglass.
Work time: 1.5 hours
Full Cure: 24 Hours
Color: Amber
Viscosity: 8,000 cps

I don't know what the SIKA tape is for, but I suspect that might have something to do with how the fiberglass handle goes into the eye of the hammer. Here's a screenshot of the handle by itself:

I know that Uri Hofi famously used Sikaflex-11 FC polyurethane adhesive sealant for attaching his hammer heads, but has anyone ever tried using anything like this epoxy?

[Frosty]

The tape might be to provide a leak proof seal between the head and handle so it doesn't leave runs, drips or errors. No telling though it might just be marketing, a macguffin.

A couple years ago we were talking about epoxy vs. other knife handle adhesives and I spent quite a while on another forum reading the archives. What I discovered after looking into different makers is, Epoxies and any other adhesives is a very competitive market and manufacturers have to keep up or lose their market. The epoxy you bought last year is out of date and discontinues this year. 

Uri's Sikaflex is ancient history and it was his New hammer handle adhesive then.

Frosty The Lucky.

[Ridgeway Forge Studio]

I have always avoided using fiberglass handles. I don’t like how they feel in the hand and the weight balance is always off.

does Warwood’s epoxy remain exclusive to their fiberglass handles/is there any good epoxy for wood handles?

[Frosty]

I've never used anything but wedges for wooden handles.

Frosty The Lucky.

[Ridgeway Forge Studio]

I have an interesting hammer I received as a gift from Fontana Forge, back when he was closing down shop. I’ll see if I have a picture. The handle has a kerf cut perpendicular to the hammer head down the shaft about 3”, it is wedged as normal with the rationale that the gap would provide enough flex to minimize handle vibrations. I will say it seems to work very well. 

[Frosty]

I look forward to the seeing a pic, I'm not familiar with handle.

Frosty The Lucky.

[BillyBones]

After i set the wedges in my handles i soak the head in linseed oil for a couple days. The late Thomas Powers taught me that trick. 

[Bull Sigh]

I used to work for a large chemical company that makes a wide range of epoxies.  I spent a few years supporting epoxy research, mostly updating testing methods and making new composites.  It was fun work because we were breaking things and getting paid for it.  The research team had a long history of making composites like fiberglass and related materials.  My part mostly focused on carbon fiber composites for military applications.  We won the contract for the F117A skin and helped formulate it with the DOD's proprietary additives.  

Relative to this thread, I fiddled around with wood/epoxy laminates testing and did some steel/wood/epoxy glue-ups.  I was shocked to see how an optimal epoxy made incredibly strong wood/epoxy laminates.  Wood/epoxy/steel glue ups were much trickier to understand, probably due to the stiffness of the steel we were working with and the compliance of the wood.  I took double bit axe heads with hickory handles to failure without epoxy, then tried to make epoxy glue-ups out-perform the without-epoxy axes.  I had to add texture to the steel inside of the handle hole to out-perform the without-epoxy axes.  

Epoxy will penetrate many soft- and hardwoods and form a very strong bond.  You can take SPF 2x4's and make a clean-up cuts to the end grain and glue the cleaned end-grain together and get an amazingly strong bond, way beyond a product like Gorilla Glue.  If you do a TRS-type failure test, it will often fail about 1/2" away from the glue joint.  That is due to the epoxy penetration into the wood, which forms a strong composite (ish) zone that is stiff enough to make a sort of stress-riser area during testing in the wood outside the impregnation zone.  

Under the best outcomes, the textured steel / epoxy / hickory glue up will out-perform a without-epoxy handle mount.  Some failure tests show failure at the steel-epoxy bond interface.  You have to have the right handle-to-steel fit that will allow an epoxy thickness that is uniform and thin.  Preliminary testing with additives in the epoxy like ultra-fine sand or talc looked promising.  My own typical axe mis-use is a larger factor than any advantage a high tech epoxy glue-up might provide.  Putting a few drops of epoxy on the wood wedge is probably the best bang-per-buck usage of epoxy in hammers or axes.  I have 8 pound and 12 pound Monster Mauls around for my sloppy wood-splitting technique.

[JHCC]

Thanks for that information, Bull Sigh. That combination of experimental data and practical experience is exactly what i was hoping for!

[Frosty]

Thank you Bull, a drop of epoxy would also lubricate the wedge so it would drive a bit deeper for a tighter fit. I used to do a little with polyester resins, mostly fiberglassing but fooled around some too. 

The universal rule was, the thinnest coat of resin that fully saturated the fabric made the strongest pieces / repairs / etc.

Frosty The Lucky.

[Bull Sigh]

Thank you for the feedback, JHCC and Frosty.

I have a little experience with polyester resins, long ago.  My dad and I built a hardwood fishing boat frame and put a polyester & fiberglass skin over it.  It held up good for ~20 years till he decided to size up and got an aluminum boat.  Great times fishing with dad...

[Frosty]

I grew up in S. California and surfing was a Thing. If you took crafts shop in high school you could buy and shape foam cores and glass a surfboard. Earlier in Jr. high crafts was an assigned class and had a section about basic fiber glassing, as did wood shop. 

The trick to keep polyester resin impregnated fiber glass cloth from delaminating from wood is to use the intended wooden object as the slapping target for cleaning your brushes. The diluted resin would soak into the wood cells and set after the toluene evaporated out.

Modern resins won't do that, they curdle and don't cure well if at all. 

I taught Dad how to repair the boat where it got hit by another one and once where Dad rammed the dock. Repaired my Corvette's left headlight where it got backed into. I didn't have a mold so I spent a lot of time and elbow grease making my fender and headlights right. 

I worked in a rubber plant making hot and cold air ducting for aircraft where I learned I don't like spending all day breathing solvent fumes. 

It wouldn't be so bad now days, there are good respirators available rated for particular solvent types and protective clothing that will keep it off your hide effectively. Wear ear plugs! They aren't perfect but are probably probably good enough.

Frosty The Lucky.

[Bull Sigh]

Wild.  You have loads of real experience.  I used to use spit-glued toilet paper for ear plugs at rock concerts.  I've run front of house quite a bit, the last 10 years of that with high quality noise suppression earphones.  I shoot handguns, rifles and shotgun alot, so for that I use plugs plus headphones.

[Frosty]

I've used toilet paper ear plugs but modern TP dissolves too quickly if you get it wet.

I wore plugs and Peltor muffs on the drill rig. Noise canceling ear protection is THE way to go, sure wish I had my Bose muffs back then.

Been a while since I went shooting. <sigh>

Frosty The Lucky.