discussion Liquid Cement Shelf Life?

[LeytonO]

Just wondering if liquid cement has a shelf life?
Bought some Tamiya Extra Thin in April 2021, wife became poorly and only came back to model making end of last year.
Doesn't seem to be as effective as I remember, so wondered if can become stale after the bottle being opened for three years.

Any new kids on the block since I last bought it, seen Mr Cement S get good things said about it.

Thanks

 

[Jim R]

Never thought of it as having a sell by date. I know that it evaporates if you leave the top off. I once left the top off a bottle of EMA Plastic Weld over night and come morning the level had dropped considerably

 

[LeytonO]

Never thought of it as having a sell by date. I know that it evaporates if you leave the top off. I once left the top off a bottle of EMA Plastic Weld over night and come morning the level had dropped considerably

Bit like my beer bottles then.
I take the cap off and in no time they're empty.

More seriously though, the level hasn't dropped.
Probably just my imagination, but I'll buy some more just in case.

 

[Airborne01]

Had no problems whatsoever with my 'Vintage Cru' adhesives!
Steve

 

[John]

I’ve had some extra thin for a long time, even the label has bleached, I didn’t think it was as good as it used to be so I got a new bottle and it was completely different, worked how it should.

 

[LeytonO]

New it is then, no point messing about for a fiver or so.
As the saying goes "don't spoil the tank for a ha'porth of extra thin"
Or something like that anyway

 

[AlexBB]

Tamiya Extra Thin is made up of 50% N-Butyl Acetate CAS No 123-86-4 & 50% Acetone CAS No 67-64-1.

With the top off the Acetone will tend to evaporate faster than the N-Butyl Acetate as it has a much lower boiling point, 56.08 C Vs 126.1 C.
This will make the cement not quite as aggressive, have less 'bite' so to speak.

It is technically possible that even capped there could be some minor evaporation of the Acetone, and though I say possible, if its probable is another matter and actually proving that in a real world situation is something that I guess no one would bother trying to prove. Though if anyone has access to a Mass Spectrometer you could do a test, sample some now and verify the % of each solvent then store the bottle appropriately for say 5 years and then sample it again!! I guess its not something anyone will do lol...

Neither chemical has a shelf life as such and does not technically degrade under 'normal' storage conditions as long as not exposed to bright sunlight or contaminated by bacteria.

 

[LeytonO]

Think i'll just get a new bottle.
Anyone want the old one to undertake intensive testing?
No, I thought not

 

[stillp]

Chuck some bits of sprue in the old bottle to make your own putty.

 

[Jim R]

That's interesting Alex. Makes perfect sense. If the different components of the glue have different volatilities then the composition will change over time. Thanks