Friday, June 3, 2011

Soap Math

There's something wrong with a mother who washes out a measuring cup with soap and water after she's only measured water in it. ~Erma Bombeck

I could begin washing clothes the really old fashion way! I mean I am an old fashion girl at heart...but also very practical and so very thankful for washing machines. Now, if something is worth the extra effort to do, I will do it, but I must be convinced it is worth the effort because there are usually modern alternatives that are more convenient. My daughter often thinks, because she does not like learning math, that she does not need it and yet her father and I point out when she is using math...which is nearly every day (just like we told her). She is learning that math comes in very handy when we need to determine the balance between savings and effort.

The Recipe
I made my homemade laundry soap and now I will figure out if it is a savings or not. First I had to buy the items in these quantities.

$1.29 - Fels Naptha Washing Soap per bar (I got three.)
$2.79 - Arm & Hammer Super Washing Soda 55 oz.
$3.99 - 20 Mule Team Borax 76 oz.

I also had to decide which of the formulas I would make because opinions vary and some do better depending on the hardness of the water. Here the water is pretty soft so I was not too concerned in that respect. I did a test load with black clothing first with a 1:1:1 ratio adding 2 tablespoons to the wash just to see if it would dissolve well because I had never used any dry detergent in my front loader before. (In fact, I have not used powder detergent since I can remember and I have pretty good memory.)

I decided to make one of the powder formulas mostly because it takes up less space and is less fuss as the liquid gels somewhat that must be stirred or shaken before use. Instead of the 1:1:1 ratio I used for my trial, I decided on a cheaper formula which is one bar of Fels Naptha and 2 cups of each the washing soda and borax.

$1.29 - One bar of washing soap very finely grated is about 1¼ cup
$ .93 - 2 cups of washing soda is roughly ⅓ of a box
$1.00 - 2 cups of borax is roughly ¼ of a box

Now I have 5¼ cup of powder detergent. I found that many people suggested just using 2 tablespoons while others recommended using 1 tablespoon for regular loads and 2 tablespoons for heavily soiled loads. Let's say that I have just regular loads for my cost comparison.

Comparing Costs
There are 16 tablespoons in a cup, 5.25 (or 5¼) x 16 = 84, so I have 84 tablespoons of detergent. Now dividing the cost by the number of tablespoons: $3.22 ÷ 84 = .0383 or just under 4¢ per load.

How does that compare to my regular detergent? I use Era HE, one of the few that do not leave an overwhelming scent nor bothers my skin and cleans very well which I purchase at Sam's Club for $10.98. It does 110 regular loads. That is about 10¢ per load. It appears to be a real savings there, however I rarely use the full recommended amount for the regular detergent. Actually, I use ½ to ¾ of the recommended amount depending on the load, making my cost 5¢ to 8¢ per load, perhaps 7¢ on average.

Another way to look at this, for my big picture friends who get lost with detailed math facts, is that I purchased enough to make three batches. The cost of the three soap bars, one box of washing soda, and one box of borax (disregarding the 2 cups left over, about $1 worth) is $10.65. That is 252 loads at one tablespoon compared to the Era at $10.98 for 110 loads or something closer to 180 loads for me. I would estimate that would be between 25% to 30% of a savings even so. It is not as much as I hoped for, but it is significant.

Other Considerations
So, it is a bit of a savings in the long run for us, probably much more for large families, but it is not much of a savings if the homemade formula does not clean as well and that will take some time to tell. I have both read websites and heard from a friend that the clothes can look a bit dingy over time. Then it is suggested to either add a booster like Oxiclean now and then or wash a number of loads in regular detergent to get them back to that brighter look. This caused me to wonder if two tablespoons would be better or if the newer detergents have certain ingredients lacking in the homemade formula, so this happens no matter how much is used.

Now there are a few of other factors. Some assume it is better for the environment because these are natural ingredients. Well, I am not so sure about that and it would take extensive research to determine. As I just mentioned in a previous post, I found a weed killer that is very safe for people and animals, but the salt in particular can do terrible damage to all plants even though it is "natural."

The homemade formula may be less irritating for sensitive skin types, but I found Era does that for me already and I was happy with it. The only reasons I decided to do this was the thrift factor and to teach my daughter that we can make such things and decide if they are worth doing. Just because the cost is less does not mean it is worth the effort and time.

Liquid Compared to Powder
There is one more thing I would address on this subject. I have found several websites that claim the cost of just a penny or two or even up to three per load. Yes, some are older sites and the price of the items were cheaper, but some were not. Most of them referred to the liquid formula, which requires the soap bar to be grated and melted in some hot water. The other ingredients are added with more water and it all semi gels in a few hours. Here again formulas vary but I will use the same portions for my comparison.

1 one grated bar soap
1 quart of hot water for melting
2 cups borax
2 cups washing soda
2 gallons of water

With about 9 quarts of the gel detergent and the recommended to use ¼ cup per regular load, it formula works out to be 144 regular loads.

Since this has the same amount of the dry ingredients as my powder detergent for which I would get 84 loads, this formula is using even less that one tablespoon of the dry formula—even under 2 teaspoons of the dry ingredients actually! That is why it is just about 2¢ per load.

All that extra work of melting the washing bar soap and mixing before use to save a few more pennies can simply be done by using a slightly rounded 1½ teaspoon of the dry formula, which takes less space. The only advantage of making the liquid may be in that the ingredients are mixed more evenly than in the powder form, assuming the gel was stirred or shaken properly prior to use.

My Conclusion
Well, it is not much effort really, but I am not convinced the savings is worth it unless it does clean well at a lower amount of detergent per load. I will give this a serious trial and will try using under a tablespoon on my regular wash and more for the more soiled. I will probably still pre-treat but I will try to do that with Fels-Naptha or a small amount of the detergent with a bit of water directly on the stain. That should save me some also.

~ My Lord, thank you for the conveniences I have and that I have so many choices. Please guide me to choose wisely between cost and effort in all aspects of my life, particularly my homemaking and homeschooling. ~


  1. I have a friend who is in the process of attempting the liquid form and it smells really fresh! I'm going to share your assessment with her. Very interesting!

  2. Paula, Fels Naptha soap does have a nice fresh scent that I do not notice at all on the clothes afterward and is absolutely WONDERFUL for washing off the oils from poison ivy on the skin! I am just amazed how well it works in that respect and I think everyone should have a bar handy just for that factor alone.

    Still, it is difficult to wrap my brain around using so little detergent to add to a load of wash. I cannot help wondering if the saving factor is really in the quantity and that one could just cut her regular laundry detergent amount in half or less with the same results and far less fussing...? It will take some time to determine for me.


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