Hardware Chemicals #1: Hydrochloric Acid

Hydrochloric acid is an extremely useful and versatile chemical that has many uses around the home.

Its usefulness comes from the fact that it is a very strong mineral acid that is nonetheless generally safe to have around. This is because its bark is worse than its bite. In its concentrated form you’ll see white fumes coming off it, and if you catch a whiff of it it’ll hit you in the nose like a sledgehammer. This property alone is a strong deterrent for children and pets.But these fumes are only an irritant – they are not toxic.

If you get it on your skin it’ll sting, but it won’t burn (like sulfuric acid). And if you got it in your eyes, they’d probably survive, although it’d sting like hell. But you should be wearing safety glasses and gloves when handling it anyway.

And it’s cheap. A 20L drum from the hardware store will only set you back about $45. And because it’s concentrated, it’ll last you a long time.

So what can you do with it?

For a start, it is an excellent weed and grass killer. Make it up at about 10% (500mL in a 5L garden sprayer), add a few handfuls of salt, make the whole lot up to the 5L mark and away you go. Spray it on weeds and grass that you want to kill and you’ll start to see results within 24hr. And it doesn’t matter if some gets on the soil – there are plenty of things in the soil that will neutralize it.

And if you find something that will survive this brew (unlikely) then just increase the concentration.

It’s also an excellent chemical for rejuvenating driveways. Cement is essentially an alkaline composite. As it’s exposed to the sun and air it develops a coating of cement dust, largely composed of limestone (calcium carbonate). A 10% solution of hydrochloric acid will strip off this layer and restore it to pristine condition. A clean with a high pressure water cleaner afterwards will remove any water marks and give it a uniform look.

Have you had tiles put down and the tilers have smeared grout over the tiles? No problem – a 5% solution of hydrochloric acid will get it off easily.

What are Acids?

I think my first experience of acids was an episode of batman, where the penguin demonstrated the potency of the acid that he was about to dunk Batman in by inserting his umbrella in it. When he pulled it out, the part that had been inserted had completely dissolved.

And this is the view of acids that most people have – potent, nasty chemicals that dissolve everything in their path.

Well, although there are acids that can dissolve all sorts of things, there is no acid that will do to the penguin’s umbrella what happened on the show.

Essentially we can place acids into two categories – mineral acids and organic acids. Mineral acids attack metals mostly, whereas organic acids attack organic material.

Also, acids may be categorised according to their strength, with the vast majority of acids being weak acids, and our bodies are full of them – amino acids, fatty acids and so on.

There actually aren’t many strong acids, and only one of them (hydrochloric acid) is available to the general public in a concentrated form. Other strong acids are sulfuric, nitric, perchloric, and hydrofluoric. That’s pretty much it, although there are several mixtures that are used to provide extra potency. Aqua Regia is a mix of 1 part nitric to 4 parts hydrochloric. Piranha solution is a mix of hydrogen peroxide and sulfuric acid, and chromic acid is a mix of sulfuric acid and potassium or sodium dichromate.

Tomorrow we’ll look at hydrochloric acid and see what it can be used for around the home.


My Favourite Products #4: Ajax Powder Cleanser

Another one of my favourite products is Ajax powder cleanser:

This product, I suspect, is simply a repackaging of the old Bon Ami cleanser which has now disappeared off the market.

This kind of thing happens all the time – products are sold from one company to another, but they are usually not rebadged. In 1985, for example, when Pea-Beu was bought from Ciba Geigy by Reckitt & Colman they kept the name.

Apparently, however, Ajax decided their name had more currency than Bon Ami. Fair enough.

You’ve never seen ads for this stuff, which is a sure-fire indicator of a good product. That is, people buy it because it actually works, not because they have been told that it works, which is the case for any advertising campaign.

So what’s in this stuff? Essentially it is a powdered bleach (calcium hypochlorite – the same stuff you buy as pool granules), some inert abrasive (alumina I suspect) and a bit of copper.

The bleach is to oxidise and disinfect anything it encounters, the abrasive is simply to rub off any dirt or material on the product you’re cleaning, and the copper is simply to go blue when it gets wet, and this is because people associate blue with clean.

So there you go – Ajax Powder Cleanser – an oldie but a goodie.

An Alternative Bleach

Modern laundry detergents are highly sophisticated formulations that are able to remove most stains if used correctly.  One of the ways they do this is with bleach – laundry bleaches such as perborates and percarbonates.

The term “bleach” is a generic term – that is, it does not refer to any one particular chemical.  Most commonly, of course, it refers to the stuff that we put in swimming pools, either sodium or calcium hypochlorite.  This is the same stuff that is in Exit Mould, and any of the products that we buy from the supermarket or hardware store that are simply called “bleach”

The difference simply refers to their respective strengths.  In particular, they are oxidisers. That is, they simply oxidise things.  Many food stains for the example are large, complex dye molecules which are susceptible to oxidation.

If the laundry bleaches don’t do it, however, there is the option of using a stand alone bleach.  The problem with this, however, is that it can also oxidise the fabric – particularly cotton.

Bleach was the only way my mother knew how to get grass stains out of my cricket whites.  And consequently, they didn’t last long.  They were polyester cotton, so they were not as prone to attack as ordinary cotton, but they eventually fell apart anyway.  But there is another option – hydrogen peroxide.

I haven’t raised its in discussions before, simply because I didn’t think it was available over the counter.  Quite by accident, however, I found a company in Wangara – Tasman Chemicals – that sell it over the counter as a 50% solution, which is mighty strong.

In comparison with ordinary bleach, there are some pluses and minuses.  On the plus side, it doesn’t smell, or to be exact, it has a very fresh smell.  The reason is that it composes spontaneously into water and oxygen.  Pure oxygen has a very fresh smell, and that’s what you smell when you use it.

On the minus side, it is worse when you get it on your skin.  Or eyes.  It stings like blazes, and turns your skin white.  It eventually recovers, but it’s a very unpleasant experience – so if you are going to use it, wear gloves.

Tasman tell me that they sell its as a booster for laundry powders – that is, you add it to your wash to boost the bleaching power of your laundry detergent.  Not a bad idea if you were using a cheaper detergent.  But I don’t know how much they sell it for or whether it would be economical.

But if you had a spot stain you wanted to remove, you could spot it on the garments.  I wouldn’t use it at 50% – I’d dilute it down to 10% (one in five) and see how it went.

It would also be a handy mould remover.

As an aside, it used to be used as a disinfectant for contact lenses – and the idea is that you would neutralise it before you put the lenses on the next morning.  Unfortunately, everyone who used this at some stage, me included, forgot to neutralise it.  The consequence was that when you put it in your eye, it stung like blazes, and the problem was that you couldn’t get it out, because the stinging sensation meant that you closed your eye instinctively.

Not pleasant.

So there you go – hydrogen peroxide is a more pleasant smelling option to applications where you would normally use bleach.  But store it in a cool, dark place – it decomposes to water and oxygen upon exposure to light and heat.