Thursday, 30 March 2017

Dishwasher detergent without mystery chemicals

Distilled white vinegar rinse aid.
It's the promised follow-up on homemade dishwasher detergent! Part of our series on home and body care without mystery chemicals.

I'd been thinking about having a go at homemade dishwasher detergent for a while, basically since those pesky dishwasher tabs cornered the market completely and the last box of loose detergent disappeared from the shelf. Anybody else irritated by how often a bit of the tab remains undissolved at the end of the cycle, especially when running on an 'eco' setting? What about the extra packaging involved, with each tab in its own individual plastic wrapper? Oh, and what about the fact that the slight increase in convenience is a sneaky way for the manufacturers to get away with charging you more for less?

The usual round of online research turned up the usual spread of ways and means to achieve the desired end. Always a useful method to work out the parameters, as there is usually a multitude of ways to skin that cat. The beautiful thing is that homemade = tailor made, so be prepared to tweak the method to suit your exact requirements.

First, a couple of general points on dishwasher optimisation:

  • Clean the filter regularly!
    It's easy to forget about this altogether, but it seriously affects the operation of the machine.
  • Wash above 50°C (125°F).
    I know, I know - it's not an 'eco' setting. Here's the deal: Lower temperature washes allow potentially nasty little microorganisms to thrive in the machine. The higher temperature wash is more hygienic, cleans better and, so far as we've been able to tell, doesn't use significantly more energy. We've seen no increase (in fact, just the reverse) in our monthly electricity consumption since switching to higher temperature dishwasher cycles.
  • Invest in the most energy efficient dishwasher you can find on your budget.
    The difference in water and power consumption between A+, A++ and A+++ really adds up.

Now, on to the detergent. In the interests of full disclosure, I'll admit we didn't get it quite right on the first attempt, nor even the second. The recipe includes citric acid and soda crystals i.e. an acid and a base. It may be that in very dry climes, one can mix these with impunity in their powder form. Not so here, where relative humidity levels are generally north of 80%. So, when we put the powders together, they started to fizz gently and continued to do so for several days.

Homemade dishwasher tabs!
There was nearly a very useful consequence to this. When I noticed that the combined powders were getting a bit sticky and clumpy, I guessed that maybe we could make our own dishwasher tabs by pressing some into the compartments on an ice cube tray. It worked, but honestly, too much effort. It was the only useful material salvaged from the first batch however, as the remainder, when sealed into an airtight container, dissolved down to a small pool of goo.

That meant switching to a 2-component system. The rest was simple tweaking of proportions to suit the recipe to our particular water type (soft) and usual dish dirtiness levels (moderate).

The Recipe

That's all there is to it.
Component I - Mix a batch of this in advance and store in an airtight container. Add around 1.5 heaped tablespoons of this to the detergent compartment
  • 2 parts borax substitute
  • 2 parts soda crystals
  • 1 part coarse rock salt
  • (optional) a few drops of tea tree oil
Component II - Add around
3 teaspoons of this in with component I in the detergent compartment
  • Citric acid
For rinse aid, simply substitute white distilled vinegar. Fill the rinse aid compartment to the brim.

Here's what the ingredients do:
  • Borax substitute: Water softener. Degreaser. Mild bleaching agent (converts tiny amounts of water to hydrogen peroxide).
  • Soda crystals: Slightly more powerful degreaser. Also softens water.
  • Rock salt: the chunky crystals provide scrubbing and scouring action.
  • Citric acid: Descaling agent. Balances the pH (borax substitute and soda crystals are both quite alkaline). Improves rinse action.
  • Tea tree oil: Anti-microbial. Smells nice.
  • Vinegar: Clears streaks. Sterilising agent.

Just as we found with the homemade body care and other homemade cleaning products, this all adds up to significant cost savings without loss of performance, and eliminates the mystery, potentially unpleasant and environmentally unfriendly chemicals that seem to have found their way into all of these mass manufactured items. Happy dishwashing!

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