Pen Finishing on a Shoe String

The Roving Reporter pointed me in the direction of this video by Timberbits.com which is one of the woodturning pen suppliers in Australia.

The CA finish is something I have demonstrated on this site before (have a check under Shed.TV), but this is a bit of a different version of the technique which is interesting in itself.  The white glaze he was getting during the video I often associated with a failed finish, but even that is something I will now reassess after watching this segment.

One thing we (I assume) agree on, is CA accelerator is best done by aerosol.  I’ve tried the pump spray applicator and have a strong loathing for it (for finishing) – where it comes to just setting off the CA glue I’ve used to repair a crack in a turning, or after gluing something up, it is perfectly acceptable, but I like a nice even coat of CA, followed by a nice even covering of accelerator, rinse and repeat 20 times when doing a CA finish.

However, the aerosol can be tricky to track down (especially if you run out on a weekend, and don’t want to waste time driving to the woodwork supplier wherever that happens to be, or wait for the postman if you order online), so here is an interesting alternative. Glen 20!

It costs 1/2 as much for twice the quantity compared with a commercial accelerator.  A very curious proposition.

So time for some research. MSDS (material safety data sheets) are an excellent source of information!

Superglue / CA is ethyl cyanoacrylate which polymerises in the presence of water (and thus why it is particularly good at gluing skin!! Many claim the best accelerator is to use the fingers, although with a few difficult side effects!)

The standard accelerator is around 95% acetone (which is a ketone for those diving for their old organic chemistry books), with 2.5% toluidine (methylaniline), which is a benzene based compound.  Fortunately not all accelerators use it, as it is carcinogenic. Others use toluene which is not only a very similar compound (and is also benzene-based) but is not as toxic (still, I wouldn’t be drinking it!)  And 2.5% quinone (cyclohexadienedione) which is also benzene-based.

However it is the 95% component that interests me.  Acetone – anyone with wives, girlfriends, daughters is quite likely to have some of this in their bathroom cupboard, being the primary ingredient in nail polish remover.  What is really curious, is acetone is also effective as a CA glue remover – so why is it so effective as an accelerator??  (And from my misguided youth, I can also reveal that chloroform is a very effective CA glue remover!!) Acetone is also used as paint thinner, so as far as organic chemicals go, it is very readily available.

So what about Glen 20? Well for one, there is no benzene-based compounds.  But nor is there any acetone or other ketone (although there is a “hydrocarbon propellant”, namely butane, and that makes up around 20% of the contents).  The rest is good ol’ fashioned ethanol (around 50%) and then some undeclared stuff (which being non-hazardous is a. not likely to be an organic chemical, and b. is most likely water with a bit of scent added, but they don’t really want to tell you that you’ve just bought ethanol and water!)  Ethanol – I have a fair amount of that at home as well- in my drinks cabinet.  One in particular would probably be getting close in proportion to Glen 20 – vodka!  20% ethanol, 80% water or thereabouts.  Perhaps I should ‘clean’ more often!

Some people have mentioned baking soda is another accelerant for CA.  I’m not convinced.  Certainly, baking soda is used as a filler in conjunction with CA, and when you do that the curing of the CA is quite exothermic but I’d think that can be put down to the greater contact surface area providing more nucleation points for the glue to cure from (and the faster it cures, the hotter the result).  In that respect it has accelerated the curing process, but it has had to become a part of the bond to perform the role.  You end up with a different result than if the CA had cured of its own accord, whereas traditional CA accelerants result in an identical result, just faster.

The question is then: how does Glen 20 work?  We can go on the anecdotal evidence from Timberbits’ video that it does.  Work that is.

I wonder, and I probably won’t get an answer on this, but the polymerisation of CA requires water.  More precisely, it requires hydroxide ions.  And what is alcohol, but an alkane carbon chain with a hydroxide ion attached?

Water

Ethanol

Either way, there is the hydroxide ion the CA requires (and for those playing at home, it is the red-white ball combination, with red representing oxygen, and white hydrogen).  And if not from the ethanol, there is still a fair chunk of water in Glen 20.  I’ll have to try it to see if just simply spraying with water is sufficient to speed up the process.  I’m sure someone must have a tube nearby that they can try and report back!

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