A little while ago I discovered that the New Internationalist web-shop were selling Fair Trade Soap Nuts. According to the site, “Soapnuts (Sapindus mukorossi) are an environmentally friendly, sustainably produced, bio-degradable and compostable alternative to commercial laundry detergents.” That sounded intriguing, and the product is fair trade, so I put in an order and decided to give them a go.
Now, those of you who know me know that I like my music heavy and my claims empirically verified, so I decided to do an experiment to test how well the soapnuts worked. Before receiving the soapnuts, I used Ecostore Front Loader Laundry Powder. I am very happy with that detergent – it works well, and the company have gone to great lengths to make their product as environmentally friendly as possible – so I have used that detergent for the comparison, as the control.
Methods and Materials
Staining the shirt
I cut the back panel out of a shirt that my partner had literally worn to death, and smeared lines of staining things onto it. For reasons explained below, I repeated this twice. For both trials I left the shirt out in the Brisbane sun for the stains to dry on.
In the first trial the stains were (from top to bottom): kecap manis – a kind of sweet soya sauce from Indonesia (yum!), tomato sauce, red wine, and coffee (Fairtrade certified of course).
In the second trial the stains were: black boot polish, green food colouring, red food colouring, yellow food colouring, bicycle grease (fresh from my bike chain). I accidentally put the bike chain grease on the wrong side of the fabric on one piece, but the only difference that should make is to make photographing the results difficult.
Making soapnut liquid
I looked through the instructions that came with my soapnuts bag, and it suggested a variety of ways of using them, including just throwing them into the wash in the little cotton bags provided – reusing them 4-6 times – or creating a laundry liquid by boiling the nuts in water. I decided to go with the latter, as I figured I’d be able to get the most out of them that way and get the most uniform results across washes. Unfortunately they didn’t tell me how much of the resulting liquid to use per wash, but I went online and the consensus seemed to be about 3 Tbsp or so.
The soapnuts themselves aren’t actually nuts but the semi-dried shells of some fruit related to Lychees. For this reason they’re also known as “soapberries”. The shells are a little bit soft to the touch and reminded me of dried-out sultanas, both in appearance and smell. The smell wasn’t very strong and kind of pleasant.
As per the instructions, I put
15 to 20 17 half-shells into 500 mL of water, boiled it for 10 minutes, and sieved out the shells, resulting in a little over 250 mL of liquid or 19 Tbsp. The liquid that resulted was ever so lightly sudsy, didn’t smell like much, and was light brown in colour. The shells came out looking soft and smelling like tamarind or sultanas, and when I squeezed them they were all pulpy and slippery, which made me wonder if I had boiled them hard enough. But I had followed the instructions, so I resisted the urge to eat one and threw them into the compost bin.
While the liquid cooled, I counted the half-shells remaining in the bag. I estimate that there are about 410 half-shells per 500 g bag.
I reserved 3 Tbsp of soapnut liquid for the wash, and put the remainder into an ice-cube tray to put into the freezer. By some miracle, I had produced exactly the right amount to fill an ice-cube tray and do one wash. Once the cubes were frozen, I put them into a freezer bag and into the freezer door to conserve valuable fridge real-estate.
I separated my laundry into two approximately equal loads. Included in each of the loads were rinsed nappies and a set of Carlo’s riding clothes.
For the soap nuts wash, I put the 3 Tbsp of soapnut liquid into the little tray thingo where I usually put the laundry powder, and turned it on to a normal cotton cycle at 30 deg C. (I have since found that 3 ice-cubes of soapnut liquid melted in a cup of hot water can also be put through the dispenser.) As warned by the instructions, the soapnut liquid did not produce any sudsing that I could discern through the washing-machine window.
I have since discovered that ice-cubes of soapnut liquid melted in a cup of hot water can be used as well.
Name brand top loader laundry detergent in Australia ranges from 22c to 73c per wash (source). I calculate the cost per wash for the two detergents used in this experiment as:
- New Internationalist Fair Trade Soapnuts: 14c / wash, including shipping
- Ecostore Top Loader Laundry Powder: 27c / wash
See footnote for details of calculation.
Results on ordinary dirty clothes
Ecostore detergent is free of fragrances and so does not leave a smell on clothes. I could not detect any difference in appearance or smell between the Ecostore detergent washed clothes and the Fair Trade Soapnuts washed clothes. There was a faint smell of soapnuts when the clothes were pulled out of the washing machine (smells a bit like tamarind water or sultanas), but this disappeared once the clothes were dry.
Stained shirt Trial 1 (kecap manis, tomato sauce, red wine, and coffee)
Both the Ecostore detergent and Fair Trade Soapnuts completely removed the stains used in Trial 1. For this reason, a second trial was performed with more difficult stains (Trial 2 below).
Stained shirt Trial 2 (boot polish, green red and yellow food dye, bike chain grease)
Both the Ecostore detergent and the Fair Trade Soapnuts completely removed the food dyes. There was a trace amount of boot polish remaining on each shirt piece, however it was such a small amount that it was difficult to determine which laundry detergent had performed better.
There was a small amount of bike chain grease remaining on each shirt piece, with the Fair Trade Soapnuts treatment having noticeably more bike grease remaining than the Ecostore detergent treatment.
New Internationalist’s Soapnuts are at least half the price of normal laundry detergent, and they are natural, organic, biodegradeable, compostable, and WFTO recognised Fair Trade. Soapnuts also perform just as well as normal laundry detergent for most stains, and perform only slightly worse for bike chain grease. Consequently, the author recommends the use of soapnuts as an ethical and effective alternative to normal detergent for ordinary laundry washing.
The author would like to thank Carlo for finally letting go of that ratty old shirt. The author did not receive any funding or any other payment or incentive for this study. This post was not an “advertisement” for this product, and I did not receive anything from anyone for “endorsing” this product.
Soapnuts cost-per-wash calculation:
$20.89 (incl. shipping) per bag /[(410 half shells/17 half shells per cook) * 19 Tbsp per cook / 3 Tbsp per wash] = $0.14 per wash.
Note that my estimate of 152.6 washes per bag is ~ 3/4 of their estimate, the latter presumably being based on the “throw a handful straight in the wash and use the same nuts for 4 – 6 consecutive washes” method.
Ecostore Top Loader Laundry powder cost-per-wash calculation
$8.79 per box / 32 washes per box = $0.27 per wash.