The Chemistry of Clothes Washing #13: Summary

The last dozen posts or so have all discussed various aspects of washing clothes.  Now I’ll summarise it all and make a few comments about some mistakes that people make.

You can wash in hot or cold water using powder or liquid detergents.  Detergents range from the el cheapo brands that don’t contain much more than a basic surfactants and a bit of washing soda, to premium brands that contain alkaline cleaning salts (washing soda and silicates), surfactants, builders, bleaches, enzymes, antiredeposition agents, fluorescing agents and of course fragrances.

In general a hot wash will outperform a cold wash, for two main reasons – firstly, the laundry bleaches are less active in cold water, and secondly, the enzymes are completely inactive in cold water.

Having said that however, many people wash in cold water with acceptable results.  The success of Cold Power as a brand is testament to this.  The surfactants do a good enough job of cleaning, and the enzymes work well enough to keep people happy – the fact they don’t contain laundry bleaches is a factor, but the lack of brightness of the clothes is often not an issue.

And now, here is the most common mistake that people make.

They decide that they need to cut down their energy bills, so they switch from hot wash to cold wash.  Then they think “why don’t I try to save even more money – I’ll switch from my premium brand detergent to a generic brand – surely they’re all the same.”

Then they think “why don’t I save even more money – I’ll cut down on the amount of detergent in the wash.”

This becomes a frog-in-the-hot-water situation – each modification they make to their washing technique results in a poorer and poorer wash.  But since the clothes all look the same, they don’t notice.

In my first job in the industry, I was involved with the development of Preen Trigger, and it was my job to troubleshoot customer complaints.  Occasionally, we would get people saying that Preen had stained their clothes.  Without exception, what we got when the customer sent in their garments, was a garment that was dirty all over except for the one spot where they had sprayed Preen.  Thus, they were interpreting the white spot as a stain, when in fact be very opposite was the case. In fact, the overall greyness of their clothes which was highlighted by the clean white spot told me that they had been using a poor quality detergent without antiredeposition agents, as this is exactly what you get – the dirt that washes out just redeposits somewhere else.

And I think that most people that ring up Shannon Lush’s show with questions about their clothes fall into this category – from memory there was one caller who couldn’t get deodorant stains off clothes, and another one who couldn’t get a smell out of the clothes.  In each case my reply would have been to ask them how they washed their clothes.  I would then have advised them to switch to a premium brand detergent and use either warm or hot water.

The simple fact is that modern detergents are very sophisticated products, with a cocktail of ingredients that are able to achieve levels of cleanliness that were unheard of years ago.  Consequently, there are not many stains that cannot be removed with the right detergent and/or and enzyme-based prewash.

And this was exactly the problem with the Preen complaints. In every case, the customer was using a cold wash with a generic brand detergent.  And for some unknown reason, some bright spark in a marketing department somewhere decided to market them as a “super concentrate” – that is, they expected people to believe that not only were they getting a cheaper product, but they were getting a more concentrated product, so they used less.

So the lesson is, if you are going to use a cold wash, don’t compromise on the quality of the detergent. If you are using a hot wash, you have more leeway with the cheaper brands.

Another good idea for getting better results is to choose a washing cycle with a pre-soak capability.  Washing machine manufacturers have at last woken up to something that I have known for years – it is the chemicals that do most of the work, not the agitation.  All agitation does is damage clothes.  Thus, modern washing machines all have very gentle agitation cycles.  Amongst other things, this is a reflection of the advances in detergent performance, particularly enzyme technology.

If you have a particular stain, one approach with a liquid detergent is to rub it into the stain before you do the wash – I think Dynamo even used to have this on their ads.  It’s not a good idea to do this with powdered detergents, as the more concentrated fluorescing agents can burn the clothes – although if it’s a white garment you won’t notice.

Okay, that’s all I can think of with regards to washing clothes.  Tomorrow I’ll say a bit about external treatments – particularly the use of stand alone bleaches if the washing doesn’t do the job.  If there are any aspects of clothes washing that I haven’t covered and you wish me to, please post a question in the Q&A section.