Hey Tom,
just as one of the greatest experts in the forum, js55, already mentioned in his reply, see also:
http://www.aws.org/cgi-bin/mwf/topic_show.pl?pid=64447;hl=#pid64447there is a numerous amount of discussions in regard to similar topics here to find.
From my point of view one of the most interesting ones is surely:
http://www.aws.org/cgi-bin/mwf/topic_show.pl?pid=63754;hl=stick%20electrodes#pid63754I guess the best source of information is and will ever be the electrode supplier himself.
In Germany we have a standardized information in regard to the storage conditions of stick electrodes.
I have translated it to be seen below:
"To prevent the impermissible generation of moisty electrode covers and furthermore to avoid moisture affected damages of the stick electrodes (e.g. core wire corrosion) the storage of the electrodes is recommended to be accomplished in a dry stockroom. As far as no different electrode supplier specification is available, a relative humidity of < 60% and a temperature of > + 18°C (64,4F) is to redeem."
I have once found also a suppliers information where a maximum storage time for unsealed electrodes of 2 years in general is recommended to be not exceeded.
Due to not knowing the temperature range under the stick electrodes have been stored by you in the oven, it is certainly hard to make a prediction about their current quality conditions. And finally it depends surely on the welding-application itself and the quality requirements belonging to this to answer the question if it is reasonable to use covered stick electrodes having an age of several years.
Finally I am sure that your own personal experience by estimating a practical welding trial in the shop will answer the question if the electrodes are furthermore usable or not and thus to be used for high qualitatively welding-applications.
So far my humble opinion.
Best regards,
Stephan