Tony Renshaw wrote:
>
> Gidday,
> I would like some advice on "when is the right time to discard hardener that
> appears to have darkened in colour, and gives off quite an odour (mind you,
> it may always give off this smell).
Firstly the discolouration of the hardener is OK but make sure it does
not start to crystallise. My hardener always seems to smell strongly of
ammonia but this is also OK
Incidentally there is a very easy way to prevent air from getting at the
hardener, that is to install a floating lid (we use them in the Photo
Processing trade with all our solutions which are very prone to
oxidation). Cut a piece of blue foam about 1cm thick and the same size
as the inside of the hardener container - make sure it will slide down
all the way to the bottom of the container. Wrap the foam in a plastic
bag or cling film and place on the surface of the hardener. Dont worry
that it is not a snug fit at the top of the container (unless your
container walls are paralell) as the small amount of surface exposed is
minimal. A self tapping screw in the top of the foam permits easy
removal of the lid.
My latest batch of resin has been in the resin pump for over a year
(with floating lids) and seems perfectly OK. Unfortunately due to
pressure of work not much building going on. With such infrequent use I
stir both the hardener and resin about once a month and pump the
dispenser handle otherwise it gets stiff and liable to sieze up.
Dispensed resin and hardener gets returned to the reservoirs - dont
panic, I used separate containers !
Hope this helps.
Regards
Carl Pattinson
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