you can order it online at www.the chemistrystore.com lokk under chemicals for Sodium Tripolyphosphate

Thanks gates! I had looked there earlier, but searched for STPP, not Sodium Tripolyphosphate. Now I find it just fine.

I'll be ordering some soon myself. It helps a lot and you only need a tbsp or less for most washes in a FL so it lasts a good while.

I recommend you keep it in a cool, dry place. If it's kept someplace too warm and/or humid it can gradually turn into TSP (trisodium phosphate) which is still effective, but not as effective as STPP.

In the past when I used it, it comes with a nice airight lid on it..to help keep moisture out, just got some over the weekend, so I will try it again and see how it goes

Since I have a whole house water softener I only use 1 Tsp per load. A 5Lb pail of STPP lasts a long long time. To keep it fresh I vacuum seal and freeze the stuff in 1LB packages. It last forever this way:):):)

I wouldnt think you would need it with a whole house water softener? Can you still see improvement in the wash when you add the Stpp?

With colors not so much but the whites yes.
Shamelessly taken from the Persil & STPP post below -
Wikipedia says STPP "provides a number of chemical functions including: sequestration of "water hardness", enabling surfactants to function effectively; pH buffering; dirt emulsification and prevention of deposition; hydrolysis of grease; and dissolving-dispersing dirt particles."

Thats great to know mvp460, cause my water is hard as a rock! Once I get to the end of this liquid, Im going back to Persil and will use Stpp with it

As far as "pH buffering; dirt emulsification and prevention of deposition; hydrolysis of grease; and dissolving-dispersing dirt particles", doesn't your regular detergent already do this? Your detergent would also be much more effective in soft water, so adding STPP seems unnecessary.

The laundry soap we make has STPP in it. So you're just boosting the phosphates. Car wash soap, laundry soap...they almost all have STPP, or a similar phosphate, in there.

STPP under humidity would be less effective because it will chunk up on you. Not sure you're turning it into TSP, though. There's a little chemical issue there. They are both phosphates, though.

.As far as "pH buffering; dirt emulsification and prevention of deposition; hydrolysis of grease; and dissolving-dispersing dirt particles", doesn't your regular detergent already do this? Your detergent would also be much more effective in soft water, so adding STPP seems unnecessary.

Of course all laundry detergent does this but not as effectively as STPP.

Most of the premium detergents with other premium components use less effective phosphates or none at all in order to appeal to the "green" market.

So they can market the detergent as enviromentally friendly.

So we should take something that is environmentally friendly and make it not so?

Another question... do you just add STPP to whatever would be your regular detergent dose, or do you reduce the regular detergent dose by the amount of the STPP?

I think we should each contribute $20 and have a lab conduct some tests to determine what is the best detergent and proper procedure for various water quality conditions! :)

So we should take something that is environmentally friendly and make it not so?

You can do as you wish. So can I. And everyone else on this board.

I want very clean laundry and I want my whites pure white.

The laundry detergent I use is very kind to the environment. But it can't take an old T-shirt and restore the whiteness. It also doesn't remove grease as well as I would like. Adding STTP as needed seems like a good balance.

Look. I'm not Mr. Wizard and I don't do litmus tests on my wash. In my state as in most, phosphate is banned in laundry detergent, only dishwasher soap can contain phosphates (that's why they get the dishes clean). However, commercial laundry's and businesses can use phosphates. Before I had my whole house water softener installed I used 1 Tbsp of STPP and a quarter cup of any liquid HE detergent per wash. Now I use 1Tsp of STPP and 2 or 3 Tbsp of detergent. It gets my whites white and the grease and oil stains out of my colored clothes. I'm not going to bring them to a commercial laundry (unless I hit the lottery). I'm not a scientist and I don't profess to be one but I did sleep at a Holiday Inn last year:):):)

Using STPP may have other benefits as well. I did a quick google search and found several articles about how STPP can be used to remove residue and build-up from clothing as well as washing machines. I wonder if use of STPP would inhibit the gunky build-up some people are getting in their machines?

What about using STPP in the dishwasher? I'm having a lot of trouble with what appear to be greasy white spots on my dishes.

Surely. Only need about 1/4 to 1/2 teaspoon per detergent dose. Experiment to find the minimal amount that gives results. I premix a batch of detergent & STPP in a separate container so that I have a prepared quantity ready for use.

I have a book on detergent formulations. As far as laundry detergent is concerned, the amount of STPP can be around 50% when compared to the other ingredients. The dosage should actually depend on the amount of detergent being used, so you can't actually make a blanket recommendation of how much to use until you know how much detergent someone is using.