STPP and SHMP Blend

[labboy]

So it was time to order more STPP. I ended up ordering 11 lbs of STPP and 10 lbs of SHMP (sodium hexametaphosphate) from The Chemistry Store.

Our water typically has between 150 to 300 GH when tested with an 8 in 1 test strip. I did a test fill of our LG front loader with 1 tbsp of each separately (different fills--one for SHMP and one for STPP). Both brought down the hardness to very soft when using the test strips but only made the water feel slightly slippery. I blended equal parts of both and did a test fill with 1 tbsp of the mixture. The total hardness was again very soft but the water was significantly more slippery than when using each compound independently. I know each has more affinity for either calcium or magnesium. It appears using both together has an enhancing effect on the total alkalinity (thus causing more slippery feeling).

I did notice that the SHMP was much more hygroscopic than the STPP. (There was some slight clumping in the container received from The Chemistry Store.) It will be interesting to see how it holds up now that I blended everything. (All put back into sealed containers.)

I'm also curious to see how it works when doing loads of laundry.

 

[tomturbomatic]

We only used Hexa, (which was Calgon when it was phosphated) for enhancing rinsing, but in those days detergents were phosphated. It will be interesting to see if it washes as well in combination with STPP as STPP does alone. Yes, the hexa is hygoscopic. That is why the early boxes were foil wrapped. Once opened in our damp basement, the opening got sorta gooey. Hexa is twice as effective, per gram, at sequestering calcium and magnesium salts, but STPP is usually a better bargain and is also a good builder and soil dispersant. Keep us informed.

In your tests, did you try using two tablespoons of each to see what the water felt like as opposed to combining one tablespoon of each of the two? If you left some unmixed, it would have been interesting to see how the addition of the Hexa to the middle rinse would have improved rinsing in your hard water.

 

[labboy]

Clarification

Sorry...I should have been more clear. I used 1 tbsp of the mixture at the end...basically 1/2 tbsp of each.

 

[sudsmaster]

Never used SHMP, just STTP. Interesting to learn that SHMP is perhaps best for rinsing.

Of course, if you really want to boost alkalinity, just add some washing soda. Nearly all washing detergent powders have ample amounts of the stuff, and it's a stronger alkalinizer than STPP. The down side is that it's a bit more harsh as well.

Stronger still is sodium metasilicate. It's used to "protect washer parts", presumably by interfering with the deposition of precipitates thereupon. Usually it's in powders in fairly small amounts so it doesn't add all that much to the alkalinity. Sodium silicate is also known as "water glass". I believe it's been used as a weak adhesive as well.

 

[tomturbomatic]

Sodium Silicate or water glass is how people preserved eggs before refrigeration. Eggs were put into water glass and it sealed out the oxygen and kept them from going bad for a long time.

You might have to adjust the dosage when you have a load of laundry in the machine since not only will you have acidic soils, but more water and the detergent.

 

[supersuds]

Goody, something new to try.

 

[labboy]

So I did several loads of laundry this weekend with the blended STPP/SHMP. I used 1 tbsp of the blend per load and my standard detergents (UK Persil Bio, UK Persil Color powder and UK Persil Color liquid). I used my previously determined detergent dosing (probably about 1/3 to 1/2 of the recommended dose) based on when I used straight STPP. It does seem that this blend softens better in my water than STPP alone.

Everything came out great. Rinses were clear at the first rinse except for the Persil liquid. I may have to further decrease the liquid dose when using the blend...took four rinses to get a clear rinse.

For curiosity, I also tried some (1/2 tbsp.) in the dishwasher along with phosphated Cascade Complete. Stuff gleamed at the end of the cycle...very, very nice.

 

[tomturbomatic]

Glad it works. Generally, except in very hard water, I guess, STPP works fine for lowest cost, but your blend is not unheard of. It's sort of like me and my uncold water rinsing. It makes me happy and by the grace of the Lord, I can afford it so there are no complaints.

 

[labboy]

The SHMP wasn't all that much more than the STPP. The biggest thing was having to blend it and put it back into sealed containers. What I have will probably last me two years now.