There are actual studies on the subject
And they come to these conclusions:
1) At 0°C you can store STPP in water and it remains STPP.
2) At 20ºC the disappearance of STPP in water follows first order kinetics.
I'm not posting all the conditions, methodologies, etc. so if you want them, do the research yourself - but:
Worst case (that open cardboard box next to the disgusting garbage pail under the wet, dripping sink) it will have, thanks to the exponential increase in degradation, all turned into something else as fast as I keep saying it will. A few weeks and it's basically TSP.
I stopped posting links when I realized people don't believe two plus two is four when they don't want to, but here's one site where a study may be bought - first page is free. It's enough for those who do actually believe 2 + 2 = 4.
All the other studies I have found come to the same conclusion.
So, yes, if your STPP was always properly stored and you were really cautious with it then you can keep it for quite a while. Just, from everything I've read around here and elsewhere, if you've kept that 5 Kilo bag around for a few years anywhere but in the Arizona dessert - congratulations, you've been using TSP. Not to worry, though - it's a very good cleaner. So good, in fact, until a few decades ago it was the reason we had such clean clothes despite US washers having had such short cycles.
And, yes, since this seems to be vraiment important, TSP doesn't chelate hard water minerals out like STPP does. I love STPP, use it all the time - but dislike people pretending 2+2 doesn't = 4 just 'cause they don't like me.
Sheesh. I'd put any current detergent with the addition of TSP up against one without and guarantee the addition would improve the removal of body oils and cooking/automotive oils noticeably.
http://pubs.acs.org/doi/abs/10.1021/i360018a001
And they come to these conclusions:
1) At 0°C you can store STPP in water and it remains STPP.
2) At 20ºC the disappearance of STPP in water follows first order kinetics.
I'm not posting all the conditions, methodologies, etc. so if you want them, do the research yourself - but:
Worst case (that open cardboard box next to the disgusting garbage pail under the wet, dripping sink) it will have, thanks to the exponential increase in degradation, all turned into something else as fast as I keep saying it will. A few weeks and it's basically TSP.
I stopped posting links when I realized people don't believe two plus two is four when they don't want to, but here's one site where a study may be bought - first page is free. It's enough for those who do actually believe 2 + 2 = 4.
All the other studies I have found come to the same conclusion.
So, yes, if your STPP was always properly stored and you were really cautious with it then you can keep it for quite a while. Just, from everything I've read around here and elsewhere, if you've kept that 5 Kilo bag around for a few years anywhere but in the Arizona dessert - congratulations, you've been using TSP. Not to worry, though - it's a very good cleaner. So good, in fact, until a few decades ago it was the reason we had such clean clothes despite US washers having had such short cycles.
And, yes, since this seems to be vraiment important, TSP doesn't chelate hard water minerals out like STPP does. I love STPP, use it all the time - but dislike people pretending 2+2 doesn't = 4 just 'cause they don't like me.
Sheesh. I'd put any current detergent with the addition of TSP up against one without and guarantee the addition would improve the removal of body oils and cooking/automotive oils noticeably.
http://pubs.acs.org/doi/abs/10.1021/i360018a001
