Super-glued finger

The newer formulations, applied and used properly, seem to be better.

Plain cyanoacrylates (e.g. the lower-viscosity ones) seem to be rather brittle. They don't deal well with materials that flex at all, and are best reserved for entirely-rigid materials. The low-viscosity types have very little gap-filling ability - work OK on clean breaks but not well if the joint is rough and has any air-space.

There are newer varieties - composites of cyanoacrylate and other materials, sometimes including what seems to be something like nanoparticles of rubber of some sort. These are often marketed as "toughened" cyanoacrylate. I've had better luck with these, when used as a more general-purpose adhesive. I presume that the added materials prevent small fractures from propagating through the solidified adhesive. The occasional ceramic cup or dish I've repaired with the toughened cyanoacrylate have held up OK.

Low-viscosity cyanoacrylate also makes a nice quick (and hard) finish for small lathe-turned wood object such as pens. You can use it as a structural fill, too... put a few drops into a hole, sprinkle in some baking soda (sodium bicarbonate), stand back while it fumes, and wait a minute. The result is a rock-hard white solid. To fill large holes, do this in repeated small layers for best results (warning, it exotherms a lot for the first few seconds - hot enough to burn you).

Another good one that a friend turned me onto, a year or two ago, is West Marine's G/flex 655-K. It's a thickened epoxy, sold for the purpose of repairing plastic boat hulls. It'll bond a lot of the more difficult plastics (flashing a torch flame over them for an instant is recommended - this oxidizes the low-surface-energy plastic and creates bonding sites for the epoxy to react with) and it works a charm on metal and wood as well.

My friend learned about it when he asked a supplier for a glue to use when installing stone counter-tops. He tried it out, epoxying a length of pipe and a flange to a piece of polished granite... just scuffed up the surface a bit with some carbide paper and glued the flange down. After it cured, he banged sideways on the pipe with a sledgehammer. The epoxy didn't fail, the steel didn't fail... when he managed to bang it free, the granite failed, and a bunch of crystals tore out of the slab and remained firmly cemented to the flange.

The kit isn't dirt-cheap but isn't ridiculously priced, and you get a lot of epoxy (8.4 oz). It's become my general-purpose go-to epoxy.

You'll also learn why it makes good sense to buy a small bottle of cyanoacrylate de-bonding liquid, and keep it in your shop next to the cyanoacrylate adhesive. Cheap insurance against torn skin, and having to admit an embarrassing oops to one's significant other :-)

Reply to
Dave Platt
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So you don't roughen the surfaces with glass/sandpaper?

Re elsewhere in this thread:- I'd picked up a bottle of superglue de-bonding , for such a finger-bonding emergency. Went to use it and the bottle was totally empty, the liquid had completely diffused? through the glass/cap , not a trace left, hence the procedure in the original post.

Reply to
N_Cook

I do not, no. I want as clean a surface for bonding as possible. Soft neopr ene O-Rings have enough surface texture, even when cut, to hold the glue. I n my mind, the key to the process is the second dip + baking soda. Chip off the excess, then file smooth with a good jeweler's file. Nice thing about these files is that they remove hard stuff, but more-or-less don't affect s oft materials, unlike sandpaper.

Peter Wieck Melrose Park, PA

Reply to
pfjw

The problem is most of the packs are heat-sealed together, so if you get it hot enough for the water to be driven out, the packs come apart and the dessicant material spills out. Usually, it is actually some kind of clay than silica gel.

Jon

Reply to
Jon Elson

So I found out the hard way. :-(

I tried to do this in an ordinary electric oven. I was careful to set the operating temperature to the heat that the pack label indicated was correct for renewing the packs.

Unfortunately, what seems to have happened is that the temperature of the tray on which I placed the packs, ended up significantly higher than the air temperature in the oven (not surprising since a lot of the heat is radiated from the heating coils). The plastic packets melted wherever they touched the tray, on the lower of the two trays in the oven.

I suspect that these sorts of packs would be better refreshed in a forced-air convection oven, where the black-body temperature of the surfaces doesn't rise above the air temperature by more than a bit.

Reply to
Dave Platt

Ammonia is the natural solvent of cyanoacrylic glues such as superglue. Very cheap and totally safe for the skin, but use it outside and don't inhale it!

Reply to
asdf

Or alternatively take the silica gel out of the assorted paper, plastic and other packets, and dry it loose en-masse.

Then repack it into a re-usable/re-sealable cloth bag to contain it, and yet allow passage of moisture into the crystals.

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Mike Brown: mjb[-at-]signal11.org.uk  |    http://www.signal11.org.uk
Reply to
Mike

Thats what I do. A large ex-pickle jar with bulk activated cilica gel crystals, slightly buff colour , not pure white. Then cut off the inside pocket cloth of worn trousers before dumping , tied off with crystals in, when required

Reply to
N_Cook

FWIW - the epoxy variety is G/flex 655. The "-K" is the repair kit. "-8" is just the 8 oz of epoxy ($26 at Amazon). Also available in the 5 gallon size for $860.

Reply to
Bob Engelhardt

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