I could use a little help. Coining and epoxy?

Salem Straub

Salem Straub

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Oct 20, 2008
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On a hidden tang knife, what do you guys do to either prevent epoxy from entering your coining (spacer behind guard) or clean it out after fitup?

Blackened epoxy that stays in the lows isn't an option here...

Do I remember a WIP somewhere in the past in which coining or filework was smeared with vaseline at the edges to prevent epoxy sticking to it?
 
Salem Straub said:
On a hidden tang knife, what do you guys do to either prevent epoxy from entering your coining (spacer behind guard) or clean it out after fitup?

Blackened epoxy that stays in the lows isn't an option here...

Do I remember a WIP somewhere in the past in which coining or filework was smeared with vaseline at the edges to prevent epoxy sticking to it?
Click to expand...

Brownell's acraglass also comes with a release agent,

http://www.brownells.com/gunsmith-t...leases/arcraglas-release-agent-prod41622.aspx


MSDS sheets usually give you a clue what's in it, but all I see is the volitile solvent carrier not the actual stuff
http://www.brownells.com/userdocs/M...ELEASE AGENT (60900), 3 OZ. - 080_default.pdf


or

How about a paste wax ?
 
Salem, The way I put most knives together I can work on it while the acraglass is drying. So I use the acraglass sparingly, then hit the coining with a light, very light spritz of oil. As the acraglass oozes out I use a sharp pick to get it out before it dries. If some does dry it pops out pretty easy. I have also used a toothbrush to work it out before it fully sets up. Just make sure your surrounding materials do not absorb the oil and discolor.
 
This can be messy but if you clean as you do it, it works pretty well.

Have a rag at the ready to wipe up the epoxy...

I take a air nozzle and blow the hell out of all the nooks and crannies and wipe up the epoxy that gets sprayed out. You can really aim the air blast at each crevice and get it clean.

As you blow...clean and then blow some more.
 
Thanks guys. Adam, that sounds like possibly my solution... although Sam's mention of paste wax is what I probably will go with. I remember reading about it as a release agent for tang bedding that worked well... less messy than other options perhaps.
 
Salem, I have only made folders from knife catalog kits but I used t build nice rifles and inlet the stocks and glass bed the actions in place. Almost every gunsmith I have met uses paste wax to keep the Accra glass from holding. I think that anything slippery will do. If the stocks did not want to come off easily we would put the whole thing in the freezer for a couple hours and they would pop loose. I have used Johnson'e paste and Minwax paste wax for a release agent. I hope this helps. Larry Lehman
 
I use Bowling Alley wax as a release agent when needed. A couple coats and epoxy will not adhere. Cleans off with normal solvents or just a buff.
 
Hey Salem. Release agents may help but, from my experience, they just create predictable “first to fail” joints that sometimes require a surprising amount of force to break after cure. I’d think preventative action is a better way to go here.

I know two MS who both nearly flood similar joints with WD-40 on Q-tips, etc. For sure this works great at removing excess epoxy but personally spooks me in regard to solvent wicking up between the components and killing the bond where it really matters (I have tested this personally). So I save the WD-40 and wood\brass scrapers as a last ditch solution prior to full cure.

If your materials are nickel silver/416SS for the coined spacer situation you describe I would personally just forget the release agents and organic solvents and use white vinegar instead. You can clip down a nylon toothbrush to half height to stiffen it up like a decent mini parts brush. Wrap your nogo areas in plastic wrap etc. to mask. Then just squirt some vinegar on a clean shop rag (no paper towels here), scrub your clean dry brush into that spot to slightly wet the bristles, then go to town on your assembly without fear.

I usually clamp and let the epoxy set up for an hour or two at RT then carefully dry scrape any bulk squeeze out. Then - alternating several rounds among the vinegar-wetted towel, the joint itself and a clean dry section of towel usually leaves an immaculate seam with no visible epoxy. This works great on scales too as long as mechanical fitup is precise. The added benefits are that there is only enough wetting to dissolve/remove the exposed epoxy without vinegar wicking between your components, there are few inadvertent scrapes or scratches from nylon bristles, and this doesn’t depend on great lighting/vision to do a high-quality job relatively quickly.

Not the only way for sure and will of course slightly etch your carbon steels if not protected.

FWIW I have had very good results with this method when using either Acraglass regular or WS G/Flex650 somewhere between 1 and 2 hr post mix.

I’ll be interested to see what you come up with here; you have been building some thoughtful beautiful stuff!
 
Thanks a lot for the detailed and informative post, Andy. I will absolutely file that away for future use! On this knife, the materials combination is stainless, copper coined spacer, mild steel of handle frame. So I don't think that I will opt for vinegar on cleanup this time...
I'll probably rely on acetone mostly. As you say there is some danger of compromising the glue joint, but there are alignment pins throughout and a tight fit anyway so hopefully the end product will be fine.

I think that I will use the nylon brush, should require far less flooding of the joint!
 
Sounds like a good plan Salem. Caveat…I think the key here is not less flooding, but NO flooding at all. That should be independent of the particular solvent you are using IMHO.

There is something about scrubbing with an old-school plain nylon brush (if you can find them anymore) that will cut the excess epoxy away but NOT flood the joint or surrounding surfaces if done as I described above. Several low-pressure scrubs and frequent cleaning of your brush on the wetted shop towel will leave no epoxy or visible residue (or scratches) in my experience. More light strokes with a clean brush and less solvent seem to work best for me.

Also FWIW, I would still use the vinegar on the Cu spacer, SS and mild steel frame as I would rather mask it, and/or polish off a little minor surface etch tomorrow, than sweat over the joint/seal integrity for years to come. Used sparingly, you (and boatload of other great makers) are probably OK, but acetone wicks into uncured joints more readily than anything aqueous (e.g. vinegar). It’s quick and useful to test this yourself - with your habits and materials.


BTW Sure wish you could come ride the alligator with us at Graves' shop in Shreveport this weekend - that other big hammer is not getting any younger...
 
Thanks again Andy. I sure do wish I could pop down to LA for the hammer-in... sounds like a blast. Then I could go bug Dan about how to set up that 50lb. hammer he just got!
Georgia is the closest I ever got to Louisiana, and I liked it there. Seemed comfortable.
 
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