A long time ago, I glued up two small Arkansas stones to make a combo stone. But as they set, one of the stones shifted leaving a less than acceptably lined-up combo stone. While perfectly usable, it has always bugged me and I would like to re-glue them to make things right. I used a white-black, two-part epoxy. Any suggestions on how to loosen them would be appreciated.
Any Suggestions on How to Loosen Two-Part Epoxy?
- Thread starter Alum of Potash
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I would say either accept it as is or lap the sides in line with each other and give up width. Nothing good is likely to come from trying to prize them free.
Try using steam. Put the item in a steamer basket over boiling water and cover the pot. Leave for a few minutes until it gets heated all the way through. Remove from heat and carefully try to break the glue bond by prying apart to separate.
Heat is supposed to do the trick. Maybe set it in a 200 degree oven for a while? Or try a heat gun?
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- #5
Thanks guys. I once put a black Arkansas in an low-heated oven to release some caked oil and fissures were the result, sort of like heating glass, so I may want to follow KCB's advice to leave things as they are rather than force the issue. That said, if there is a fragile line left by the glue between the stones, perhaps a wide-frame, thin-blade hacksaw, coming in from both ends (the stones in question are 4" in length) might do the trick, the friction also creating the requisite heat locally. Think I'll give that a try.
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rbscebu
Girls call me Makaluod
Take it to a stonemason and get him to cut the stones along the glue line. He will have the gear and the skill. You then lap (wet and dry used wet) the sawn surfaces reasonably flat and re-glue. It might cost you a few dollars but better than ruining the stones.
To find a stonemason near you, search for headstones.
To find a stonemason near you, search for headstones.
Unfortunately it's not that easy tbh.
I don't know how it would affect Arks, but about ten mins in boiling water would do it. Or indeed oil. Oil might even be better because epoxy doesn't bond to oiled stuff, and some of the trouble of breaking a warm epoxy bond is that it re-sets. (And don't people boil novaculite stones in oil sometimes anyway?)
If that's too aggressive for the stones - steaming sounds a good idea. But probably need to be done several times over, gently trying to loosen the bond between each round.
The very best way to break or loosen an epoxy bond (ime) is actually with shock. But shock heat differences, as opposed to shock force - boiling something then putting immediately into iced water. But I'm guessing that's going to be very bad for a stone!
I don't know how it would affect Arks, but about ten mins in boiling water would do it. Or indeed oil. Oil might even be better because epoxy doesn't bond to oiled stuff, and some of the trouble of breaking a warm epoxy bond is that it re-sets. (And don't people boil novaculite stones in oil sometimes anyway?)
If that's too aggressive for the stones - steaming sounds a good idea. But probably need to be done several times over, gently trying to loosen the bond between each round.
The very best way to break or loosen an epoxy bond (ime) is actually with shock. But shock heat differences, as opposed to shock force - boiling something then putting immediately into iced water. But I'm guessing that's going to be very bad for a stone!
If you are able to get a thin hacksaw even a bit of the way down where the bond line is that'd make it easier and shorter to steam or boil after if you wanted.
If you're going just with trying to saw though - I wouldn't be thinking about wanting to create heat from friction. In fact I imagine you'd want to be cooling it down. Trying to saw warmed epoxy is not going to be fun, you also do have the problem that warm epoxy will re-set to a certain extent.
If you're going just with trying to saw though - I wouldn't be thinking about wanting to create heat from friction. In fact I imagine you'd want to be cooling it down. Trying to saw warmed epoxy is not going to be fun, you also do have the problem that warm epoxy will re-set to a certain extent.
Naked boiling epoxy does work happily - I do it a lot. And it works better than just heating in an oven. It’s more whether the stones would like 100 degs.
I imagine they’d be fine, but I’ve not done it before.
Also - both acetone and vinegar will dissolve / break epoxy bonds without heat. But that would depend on how porous the stones are.
I imagine they’d be fine, but I’ve not done it before.
Also - both acetone and vinegar will dissolve / break epoxy bonds without heat. But that would depend on how porous the stones are.
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- #11
Thanks guys. I've boiled a turkey stone in milk before, which, with the naturally occuring fissures, was arguably more fragile than an Arkansas stone. The trick was to keep the stone off the surface of the pot, so as not to be in direct contact with the heat source (which is much hotter than 212 degrees F). To do this, I placed the stone on four small balls of aluminum foil in the pot, which didn't conduct heat much. Maybe I'll try that with this combo stone to see what happens. It's a 1/2" thick hard (hard soft) Arkansas glued to a 1/4" thick black hard Arkansas, so if one's going to crack from the heat, it will probably be the black.
Steaming at normal atmospheric pressure reaches a maximum of 212 degrees. This is a process that is used commercially, so it's not a "questionable guess". Try lowering your nose around 30 degrees or so.
Steaming at normal atmospheric pressure reaches a maximum of 212 degrees. This is a process that is used commercially, so it's not a "questionable guess". Try lowering your nose around 30 degrees or so.
Well, may I ask if you have steamed Arkansas stones or novaculite to separate epoxy? His question was not the temp of steam which I don’t dispute the temp. I do say the recommendation is questionable for two reasons. First when he mentioned black/white two part epoxy it sounds like maybe JBWeld which I don’t think you can breakdown with steam. Not 100% on that. Second, it is common to heat treat and boil novaculite (Arkansas stones) and flint etc for “flint napping” in making arrowheads etc. It does alter, make brittle, create fissures etc. I think it is a called spalling or something like that. Companies sell heat treated novaculite for arrowheads like Dan’s for example. So when I say questionable, I do question if anyone suggesting heat has actually done it and without issue. Have you? If you or others have then that is great first hand experience. If not then maybe you are recommending something that will ruin his stones. That wouldn’t be good
I have boiled black/white two part epoxy to break it, though I don't think it was JBWeld.
HT of stones, including novaculite, does happen at much higher temperatures though. You can see here there's effectively no change until at least 300 degs c: Arkansas Novaculite: A Virtual Comparative Collection - http://archeology.uark.edu/novaculite/index.html?pageName=Heat%20Treatment%20of%20Novaculite
But equally I have not boiled stones before, though it seems OP (as well as others) have
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- #15
For what it's worth, the epoxy in question here is JBWeld. [Edit] Strong, stinky, stuff. [/Edit]
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JB Weld, most epoxies actually, will start to soften in boiling water. Lots of two part stuff is listed as needing 4-600F to remove it but it softens long before that stage. At the same time, some epoxy doesn't budge at 212 deg F. I am sure there is a page or 3 about softening JBW on the intertubes somewhere.
Only real danger with boiling/steaming the Arks there is if there is a fissure surrounded by internal stresses that might shift from heating. Could cause a run or split. Stones are funny like that. Could happen, prob not but it might. Heat altering of Novaculite is done at higher temps, for longer. Still, gotta take care, hope for the best but prepare for the worst.
I would probably just plunk them in a bath of acetone and forget about them for a while. If the seam is thick enough that might do it. Other than that - putting a clothes iron on top with a bit of cloth to keep the stone off the steel can work too. low slow heat. I've done this to separate glued stones but I don't think it was epoxy. IIRC, Scott did this to pull BBW off a glued Combo, or something. Was a long time ago.
FWIW - I'd prob just lap it flush all around and move on, path of least resistance unless the overhang is significant.
Only real danger with boiling/steaming the Arks there is if there is a fissure surrounded by internal stresses that might shift from heating. Could cause a run or split. Stones are funny like that. Could happen, prob not but it might. Heat altering of Novaculite is done at higher temps, for longer. Still, gotta take care, hope for the best but prepare for the worst.
I would probably just plunk them in a bath of acetone and forget about them for a while. If the seam is thick enough that might do it. Other than that - putting a clothes iron on top with a bit of cloth to keep the stone off the steel can work too. low slow heat. I've done this to separate glued stones but I don't think it was epoxy. IIRC, Scott did this to pull BBW off a glued Combo, or something. Was a long time ago.
FWIW - I'd prob just lap it flush all around and move on, path of least resistance unless the overhang is significant.
One problem I see with heat is that different materials expand at different rates. So you could have one stone trying to expand against the other with the epoxy perhaps still fully intact or, worse, expanding at its own rate. Definitely a recipe for cracks or breakage.
If you do heat it do so very very slowly. Much better to move too slowly than too quickly.
I'd lap it if it's lappable. Or I'd use a tile saw. A wet saw with a diamond blade. That'll gently cut (really it grinds with a diamond edge) marble, granite, and glass-like ceramic. (I used mine on a JNat I bought broken. Made a few nice little stones and plenty of tomonagura!) Either cut your stones square (lap) or slice it down the middle to separate the stones if that's what you want.
Lesson learned. Either way, good luck!
If you do heat it do so very very slowly. Much better to move too slowly than too quickly.
I'd lap it if it's lappable. Or I'd use a tile saw. A wet saw with a diamond blade. That'll gently cut (really it grinds with a diamond edge) marble, granite, and glass-like ceramic. (I used mine on a JNat I bought broken. Made a few nice little stones and plenty of tomonagura!) Either cut your stones square (lap) or slice it down the middle to separate the stones if that's what you want.
Lesson learned. Either way, good luck!
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- #18
The stones are only 4" x 1-5/8", so lapping or trimming things down on a tile cutter doesn't have much appeal as they would only get smaller. Took a look again, and they are perfectly functional as glued, so it's mostly about aesthetics. And were I to separate them and re-glue them, it turns out that one stone is cut a little bit larger than the other, so a perfect alignment will not occur apart from lapping or trimming anyway. Guess I'll just leave things as they are, even though seeking to separate them through boiling would have been part of the learning process.
I have boiled arks without any issues. I have also tested them according to AASHTO T-85 which is the approved method for specific gravity and absorption for road construction. It involves an over night soak in water and then drying in an oven at 230 F. All with out issue, but like Gamma said if there is a fault in the stone it could go sideways.
I use heat to soften epoxy in old axe heads like the perma bonded Plumbs. I usually use a heat gun, but I think boiling water would be a better choice with stones.
I use heat to soften epoxy in old axe heads like the perma bonded Plumbs. I usually use a heat gun, but I think boiling water would be a better choice with stones.
Steaming at normal atmospheric pressure reaches a maximum of 212 degrees. This is a process that is used commercially, so it's not a "questionable guess". Try lowering your nose around 30 degrees or so.
That is not necessarily true. You need to qualify that statement for it to be so: the steam above a boiling pot of water will generally be at a maximum of 212° F at STP. Steam can get much much hotter than that if it's produced/heated in other manners.
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