Storage life of thiourea/thiocarbamide and sodium hydroxide solutions?

I'd like to experiment with split toning using a mild rehalogenating bleach followed by a thiourea and sodium hydroxide toner. How long can I expect separate 10% solutions of thiourea and sodium hydroxide to last? They'll be mixed together at the time of use. I know I should store the lye solution in plastic (HDPE or PET); is HDPE/PET OK for the thiourea solution or should I use glass? While I believe the lifetime of the sodium hydroxide solution is pretty much unlimited, Google has not (yet) provided me with answers relating to thiourea (also referred to as thiocarbamide).

Thanks!

I've had 10% solutions of both stored for the past eighteen months (the sodium hydroxide is in a thoroughly washed out container which previously held Ilford Multigrade Paper Developer and the thiourea is stored in a glass bottle simply because it was all I had on hand at the time). Both stock solutions seem to behave in working solutions exactly as they did when I first mixed them.
I'm a complete novice with toning and I haven't run any sort of scientifically acceptable comparative tests so please take my experience as just that!

I've had stock solutions stored for 3 or 4 years and still working well, Iv'e had the W/S solutions stored in plastic bottles for 12 to 18 months, still working well, so to me it seems that both the stock and WS solutions keep well, I test the W/S with an old print, maybe a test print or something before I commit a good print, if it is still working I use it, if not then mix up fresh,
As above i haven't any scientfic tests, just my many years of practical experiance

Concur, I have both in those plastic hospital saline drip bottles for 4+ years now. Admit, I was a little worried about the NaOH, but there it is, and I use it to refresh from time to time.