On 28/04/2015 23:09, Sjouke Burry wrote:
On 28.04.15 15:48, N_Cook wrote:
New cone for an EV SX 200, 12 inch speaker. Removing the old cone. I use
a hot air gun on a low setting, so air temp whatever 2 or 3 inches from
nozzle , rated 320 deg C on low setting. Suspension rim came away as
normal. But the spider , looked as though it was to burst into flame, an
alarming amount of jetting and billowing white smoke came off the join.
Quickly removed the hot air gun and gradually the smoke died away.
Didn't smell anything particularly chemically and no throat iritation.
Continued removing the spider with the hot air gun more like 5 inches
away and no repeat of the "smoke". Some sort of chemical reaction ,
initiated by heat, but not combustion?. A white deposit left from the
glue , looking like aluminium oxide but the basket metal was not
affected I think, good machined surface, no obvious corrossion there or
anywhere else on the basket.

That is whats left when you burn silicon glue.
White powder.

Different glue used for spider and main rim, perhaps someone had been in
there before, to refit the spider, unknown history with this speaker.
It looks as though the cone was driven outward , forcefully at some
point in its history. A slight double crease in the cone suggesting the
outwards action, perhaps powerful enough excursion to pull the spider off.