STPP Quality?

[littlegreeny]

I purchased 2 pounds of STPP from the Dafna Store on ebay 6 years ago. I still have most of it left because it never dissolved the few times I tried it. I thought I'd try it again today and I noticed residue left over in the dispenser so I grabbed a glass of water and added about 1.5 Tbsp and this is the hard residue left. It coated the bottom of the glass and cracked when I hit it with a spoon. It's been stored in an airtight plastic container and shows no signs of being moisture damaged (it's a very dry, fine powder).

Is this normal or was I sold an inferior product like TSP?

 

[mark_wpduet]

Not normal at least from my experience. I have an OLD container of STPP I got from soapgoods.com a long time ago...maybe longer than six years ago.. been so long I can't remember...I recently started using it again because I cleaned out some cupboards and found it...in the sealed container of course and there was no clumping at all and everything dissolves.

 

[Marky_Mark]

I had the same experience as you with STPP.  It did seem to clump and didn’t always completely dissolve.  My parents-in-law use it for their dishwasher, so I’ll try dissolving some of theirs in a glass and see what happens. 

 

[launderess]

Have used vintage boxes of Calgon (mixture of STPP and SHMP), along with STPP bought from the Chemistry store many years ago now. None of them clump, and or have issues dissolving. If amounts are added to say a jar of water not only does stuff dissolve, but solution is clear, which is as it should be.

Now STPP will eventually break down into TSP IIRC, especially if improperly stored.

Nearly all these places selling STPP or other such chemicals are bulk resellers. They buy STPP, borax, sodium percarbonate, etc.. in huge bulk sacks, then repackage smaller amounts to sell on. Thing is you don't know how long they've had that product sitting about, and under what conditions.

 

[sudsmaster]

I bought about 20 lbs of STPP about 10-15 years ago from a local chemical supply store. It is a medium grain powder and never seems to fail to dissolve. I suspect whoever you got your STPP from either failed to store it properly or mixed it in with some unknown substance.

 

[littlegreeny]

Thanks everyone for the comments. Sounds like I should probably just toss what I have left.

 

[launderess]

Waste Not, Want Not....

That's what I say....

Grind stuff up into a powder (or smash bits into smaller bits so will dissolve) and use as scouring powder, add a bit when mixing up a bucket of cleaning solution to mop floors, clean walls...

 

[tomturbomatic]

That adulterated product could be used by pouring boiling water over it and letting it steep then pour the solution off into the laundry and discard the solid on the soil.