Thread Number: 71300  /  Tag: Detergents and Additives
STPP for the washer
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Post# 943653   6/15/2017 at 21:37 by JesseD (Saint Marys, Pennsylvania)        

I have been reading some older discussions about adding STPP to laundry detergent to make up for the missing phosphates. I was wondering how well it helps and where I could get some and also how it affects the clothes.

Post# 943664 , Reply# 1   6/15/2017 at 22:31 by kb0nes (Burnsville, MN)        

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Out of curiosity what are you using for detergent(s)?

Post# 943666 , Reply# 2   6/15/2017 at 22:35 by DADoES (TX, U.S. of A.)        

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I've been adding STPP for upwards of 8 years.  Several online sources are available, including and sellers via Amazon and eBay.

Post# 943668 , Reply# 3   6/15/2017 at 22:39 by JesseD (Saint Marys, Pennsylvania)        

I use Tide powder original or mountain spring.

Post# 943685 , Reply# 4   6/16/2017 at 00:35 by sudsmaster (East of SF, West of Eden)        

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The latest Tide powder is pretty good stuff. Unless you are not getting various stains, esp stuff like ground in garden dirt, out of clothing, you might not need STPP added. And, I'm a big fan of STPP, but have found the Tide powder I bought in the last year or two works well enough without it. Thus I haven't yet resorted to amending the powder with STPP. However in the past I've amended another powder, Sears Ultra Plus HE, with about 30% by weight STPP. That worked fairly well, but the finished laundry tended to be not as soft as with just Tide powder alone.

It's up to you. If you have very hard water, then STPP may help considerably to prevent the redeposition of precipitated calcium and magnesium carbonates onto not only your laundry, but also on internal washer parts. Again, from the way it performs, I'm guessing the chemists at Tide have figured out how to minimize this without needing STPP. On the other hand, the municipal tap water here is moderately soft (2-5 grains) so this isn't as big a problem here as it might be at some place running on well water.

Post# 943695 , Reply# 5   6/16/2017 at 04:03 by arbilab (Ft Worth TX (Ridglea))        

Our water is hard enough to deposit a grey mineral ring at the toilet bowl waterline in a week.   I find that generous use of Tide powder plus ~tbsp STPP functions as fabric softener without the glop of the bottled stuff, waterproof towels, etc.



Post# 943771 , Reply# 6   6/16/2017 at 11:27 by kb0nes (Burnsville, MN)        

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I've bought STPP from Chemistry store also. I have mechanically softened water so I have generally used very little of it. It seems to help more in the dishwasher then the laundry. You are using a good detergent, but it might be worth experimenting with especially if your water is hard.

Post# 943911 , Reply# 7   6/16/2017 at 23:30 by sudsmaster (East of SF, West of Eden)        

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I should hasten to add that STPP can function not only to prevent the deposition of hard water mineral precipitates on clothes and washer internals, but also to help break away and hold in suspension many of the same hard water minerals that are integral to soil on fabrics - you know, stuff like garden dirt. And perhaps also mineral based industrial or automotive grease. It does this better than any other single laundry additive.

However since the banning of phosphates in many products in many states and countries, the laundry detergent mfgs have devised various work arounds. IMHO, the early ones, which relied heavily on sodium carbonate, which can leave a mess when combined with hard water, didn't clean so good. It's my impression (not based on any insider knowledge) that mfgs like Persil and Tide have figured out how to get good results without phosphate. At least with their powders. I still don't think there's any liquids out there that can handle really filthy laundry as well as the top powders.

The replacments for phosphates include such oddities as zeolites (basically, aluminum silicates that capture some but not all hard water minerals in their nooks and crannies, or odd sounding organic chemicals like TAENF whatever that is. Zeolites do a good job with calcium ions but not so good with magnesium and other hard water minerals. And so on ad nauseum.

A while back I devised a home test for demonstrating part of the hard water mineral problem. In one jar I'd put some well water (we have soft muni tap water, but the well is for irrigation) and some standard laundry detergent. In another, some STPP. Shake them up, when the suds subside, you can actually see the flakes of precipitated out calcium and magnesium carbonate in the standard detergent jar, but the jar with STPP would remain crystal clear. And yes, the ppt looks like lint, but it's not so nice to have on finished laundry and it can put a layer of something akin to concrete inside the washer.

Post# 944041 , Reply# 8   6/17/2017 at 21:10 by JesseD (Saint Marys, Pennsylvania)        

Since I am trying to clean dirt from a farm so I think it will defiantly help.

Post# 944049 , Reply# 9   6/17/2017 at 23:15 by sudsmaster (East of SF, West of Eden)        

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Yes it will help with farm dirt, especially if you have clay dirt.

Post# 944157 , Reply# 10   6/18/2017 at 20:57 by panthera (Rocky Mountains)        

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You spend a lot of money on STTP try a small box of TSP. If it works well, STTP will be worth the money.

Post# 944184 , Reply# 11   6/19/2017 at 01:27 by sudsmaster (East of SF, West of Eden)        

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Used to be you could pick up a box of Calgon or White King laundry booster in the supermarket and get STPP that way.

Post# 944208 , Reply# 12   6/19/2017 at 08:23 by panthera (Rocky Mountains)        

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Worth noting, regardless of whether my autocorrect is saying STPP or STTP,STPP turns into TSP really fast no matter how well you store it.
Most people who think they're using STPP are really using a mixture of the two and quite happy with it. Buy the smallest amount you can.use it soon.

Post# 944283 , Reply# 13   6/19/2017 at 18:34 by mamapinky (blairsville pa)        

I thought it was unsafe for washers and textiles to use tsp?

Post# 944294 , Reply# 14   6/19/2017 at 20:02 by sudsmaster (East of SF, West of Eden)        
STPP turns into TSP really fast

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Not really. It has to be damp and subjected to elevated temps.

However it's a good point to remember. Part of the power of STPP is that it carries a fair amount of chemical energy. It's this energy that enabled it to latch onto hard water minerals and hold them in suspension. As with most things, entropy is always increasing, which means systems tend to migrate from higher energy states to lower energy states. With STPP that means some of the polyphosphate structure can degrade to bi- and mono- phosphate. TSP is the mono-phosphate version.

I have some STPP I've stored in the original sacks, kept in water resistant plastic tubs for over 10 years. Might be time to do another shaken pickle jar with well water test :-)

Post# 944295 , Reply# 15   6/19/2017 at 20:05 by sudsmaster (East of SF, West of Eden)        
unsafe for washers and textiles to use tsp

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I don't see why it would be, other than dumping phosphate into the waste stream with decreased benefit.

TSP is a milder alkali than the main ingredient in most laundry and dishwasher powders, sodium carbonate. So on that score it's more gentle than the main alkali in store bought. However, because it's a mono-phosphate, it won't keep hard water and soil minerals from precipitating out on fabrics and washer parts, same as sodium carbonate. In other words, it's no worse than unboosted store bought detergent, but not much better.

Post# 944309 , Reply# 16   6/19/2017 at 23:13 by panthera (Rocky Mountains)        

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Definitely does not harm to either clothes or water.

I've never had the precipitate problem with it, and when a glass of our water falls it's an open question what breaks first, the glass or the water.

That said, there's different mineral situations in each location so I don't exclude the possibility.

As to cleaning, I must disagree - it does an outstandingly better job of grease and dirt removal and enzymatic detergents clean far, far better with it than without.

As to STPP, I doubt most people who use it realize how quickly it degrades, so, yeah - most folks using "STPP" unless its fresh aren't.

I still say - try the TSP. If it makes a big difference, invest in STPP. If it doesn't, STPP won't, either.

Post# 944314 , Reply# 17   6/20/2017 at 00:01 by sudsmaster (East of SF, West of Eden)        

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I doubt that TSP would be a good indicator of how well STPP would boost laundry detergent, because it lacks the chelating ability of STPP that makes STPP so useful. Without that chelating ability one might just as well dump in more sodium carbonate (washing soda) instead.

As for STPP losing its special ability over time... I wonder if anyone has actual test data, or a literature reference, to back up the claim that it degrades rapidly even when kept dry and cool.

Data should include storage conditions, including temperature and humidity, length of storage, and any quantified loss of chelating ability over time.

Otherwise one might be tempted to dismiss such claims as unsubstantiated rumor.

Post# 944331 , Reply# 18   6/20/2017 at 03:16 by Stan (Napa CA)        
Interesting subject

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There must have been a reason for the use of STPP by detergent manufactures vs using TSP. I know that TSP is more alkaline than STPP . Maybe TSP cleans better for wall washing...paint prep. TSP will cut through grease and etch into old paint making new paint adhere. (Needs to be rinsed, and ware gloves, made that mistake once)
But wait..why would that be good for laundry or fabric.
If TSP does not suspend hard water, or form a complex with hard water ions...Then why use it in laundry?

Post# 944347 , Reply# 19   6/20/2017 at 07:44 by panthera (Rocky Mountains)        
Before this gets ridiculous

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1) STPP is a much better laundry cleaner than TSP in hard water - it chelates the minerals which interfere with cleaning. No question. That's why I use it.

2) STPP deteriorates quickly if not properly stored - it's on every data sheet, we don't need to pretend it doesn't.

3) If we're now going to pretend TSP doesn't clean and that alkaline conditions are bad for laundry then we might as well just give up.


Nobody is saying STPP isn't wonderful - it is. I use it.

BUT - TSP together with a good enzymatic laundry detergent and hot water cleans really well, especially greasy/oily stains.


Come on folks, are we really going to pretend it doesn't? Are we really going to pretend that one should spend the money on STPP without trying TSP first? That TSP doesn't clean?





Post# 944359 , Reply# 20   6/20/2017 at 09:51 by Stan (Napa CA)        
I don't doubt

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That TSP cleans. Like I said I've used it as a paint prep. And made the mistake of not wearing gloves and burnt the hell out of my hands. So I know it cuts grease. The red burnt hands showed up the day after I used it.

Panthera, how much TSP do u use for laundry use

Post# 944377 , Reply# 21   6/20/2017 at 13:25 by panthera (Rocky Mountains)        

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Here's my recipe for dirty clothes:

1/2 cup TSP

145F hot water

1/2 cup Arm&Hammer HE with enzymes

22 minute soak, 14 minute agitation

2 real rinses in a 42 year old Maytag

It never fails.

STPP, 4T instead of 1/2 cup.

Post# 944383 , Reply# 22   6/20/2017 at 14:12 by stan (Napa CA)        
Are you

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Able to do warm rinses with ur Maytag?

Post# 944385 , Reply# 23   6/20/2017 at 14:30 by panthera (Rocky Mountains)        
Back then, yup

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We've a couple, I'm using an A702 (the following year it had an extra rinse option, I just reset the dial on this one).

Lovely machine. Never had to do any work on it.

Sometimes I use a '67 Filter-Flo, especially when there's dog hair.

Post# 944391 , Reply# 24   6/20/2017 at 15:26 by earthling177 (Boston, MA)        


I just bought a small pail (forgot if it's 5 or 10 lbs) of Sodium Tripolyphosphate (STPP) from the Chemistry Store a few months ago.

It came in the sealed plastic pail. I transferred some to a small ziploc bag.

Since day 1, it has been a smooth flowing white powder that transforms into a hard rock as soon as it touches water. Cold, warm, hot, it does not matter. It takes a looong time and a lot of agitation for it to dissolve.

This has not been my experience with previous water softeners.

For the record, my water is naturally soft (0-4 grains) *most* of the year it can reach 6-8 grains in some parts of winter when the city uses water from other sources.

So yes, in my experience, STPP came to me "pre-stale", lets say.

Color me not so happy.

I'm also wondering if the majority of people who are the target market for this (traditional agitator toploaders) even notice, given that they dump the powder into the washer with other stuff, dum the clothes on top, and close the lid.

And by that I mean people in general, not folks here who like to watch the entire cycle.

   -- Paulo.

Post# 944394 , Reply# 25   6/20/2017 at 16:05 by mamapinky (blairsville pa)        

Prior to The Dafna General Store closing their store I always ordered my STPP from them than myself along with a bunch of others over on Gardenweb noticed this STPP not disolving, turning to hard clumps even in hot water. Dafna sent new bags...same thing...I ordered a small bag from the Chem store..same thing...I picked up a small bag from Pittsburgh Spice..same thing.. I haven't a clue why.

Post# 944397 , Reply# 26   6/20/2017 at 17:13 by stan (Napa CA)        
Get my STPP

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From Soap Goods, 4lb container with screw on lid.. No problem.
I only have Top Load machines, so I alway pre-dissolve any powdered substance including powdered detergent in hot water before adding. The STPP is the quickest to de solve.

Post# 944413 , Reply# 27   6/20/2017 at 19:54 by kb0nes (Burnsville, MN)        

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That is odd, I bought the exact same container from Chemistry Store. When I dummped the shot of powder into standing water in my top loader it was dissolved before it hit the bottom if of the basket. I left mine in the pail and slowly used it over the course of about a year. Never experienced anything like you describe... The powder was always free flowing as you mention and there was never any caking or issues with it dissolving. Strange

Post# 944950 , Reply# 28   6/24/2017 at 00:33 by sudsmaster (East of SF, West of Eden)        

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STPP degredation:

I guess you (Panth) need to define "proper storage", and "quickly".

Like I said before, if the STPP is kept dry and out of the heat, it will last in powder form for years. I know this from personal experience.

Now, if you leave a cardboard box of it open under the kitchen sink next to damp garbage, yeah, it might degrade. Just like powder DW detergents will as well.

But keep it dry and room temp or lower, it doesn't "degrade quickly". At least not in my book.

Post# 944952 , Reply# 29   6/24/2017 at 00:38 by sudsmaster (East of SF, West of Eden)        

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STPP that is lumpy and won't dissolve?

Most likely old stock that was not properly stored. It's absorbed moisture.

It might still work well enough. One could test its effectiveness by mixing it with warm or hot hard water in a glass jar, and noting if there's any visible precipitate. If none, then it's good to go.

As a control, do the same with a precipitating water softener like washing soda or TSP. If you see a precipitate with those ( and you should with hard water ), then you know your test regimen is good.

Don't have hard water? I suppose one could approximate it by mixing tap water with calcium cloride and magnesium sulfate.

Next question.

Post# 944997 , Reply# 30   6/24/2017 at 08:53 by panthera (Rocky Mountains)        
There are actual studies on the subject

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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. 


Post# 945102 , Reply# 31   6/24/2017 at 20:35 by mamapinky (blairsville pa)        

Panthera, I have used better part of a 20 pound bag of STPP that took some work to this could have decomposed into TSP if I'm reading you correctly...well I gotta say my clothes were wonderfully clean, fresh, and soft...LOL.....Cheryl

Post# 945803 , Reply# 32   6/29/2017 at 00:44 by sudsmaster (East of SF, West of Eden)        

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Well, Panth, I still have a couple of 50 lb sacks of STPP I bought about 15 years ago - kept relatively cool and dry in plastic bins.

As I said earlier, I have a hard water well and I can easily test the ability of the STPP I have left to see if it still keeps hard water minerals suspended and not precipitated. It's a qualitative measurement, but I think a fairly good indication of STPP's chelating and complexing capability (forming chelated complexes with hard water minerals is what gives STPP its magic powers).

I have no argument that storing STPP wet is a very bad idea. I just don't buy, without some solid evidence, that storing it dry is going to result in turning it to TSP.

Post# 945822 , Reply# 33   6/29/2017 at 06:13 by Gyrafoam (Roanoke, VA)        

I've had mine for years, slowly using it up. I dumped it into a tub with a lid when I got it from the Chemistry Store a few years ago. It's not lumpy, dissolves immediately and does a good job.

On the other hand, I have become used to having a great detergent with the Phosphate already built-in. Uses only 1/2 cup per full top-load, makes NO suds, smells just like the old "Lemon Fresh FAB". And is cheaper to use per load than granular tide.

Post# 945846 , Reply# 34   6/29/2017 at 08:15 by panthera (Rocky Mountains)        

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If anybody could store it properly, you are the type who could. The fact that nearly everyone else on the planet does not is the whole reason Automatic Detergent boxes containing the stuff warned not to keep it around too long, the whole reason commercial cleaners with it warn about proper storage.

Come on, you're just being combative out of personal reasons. I've provide the scientific basis for my assertions, it's silly to mix personal feelings with fact. 


STPP has wonderful cleaning abilities, I use it. But - this 'TSP' is of no value as a laundry/dish cleanser is just plain wrong. I've never had the problems with it which are theoretically possible. Water chemistry plays a role in that. So does accepting that STPP doesn't remain STPP for long unless stored with great care. 

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