Sodium percarbonate with soda crystals?

[Kev888]

Hi all,

For cleaning (where thin bleach isn't suitable or effective enough) I tend to use soda crystals (washing soda) or occasionally sodium percarbonate. I'm wondering, though, if it may actually be more effective to make a mix of the two, maybe also with a bit of detergent like washing up liquid or washing powder?

Sorry if this seems a daft question - chemistry is definately not my strong point.

Cheers
Kev

[Graham]

Most of the OXi products - except Ecover - are just 30% sodium percarbonate; it is then bulked out with sodium carbonate (washing soda), so you will not achieve much. Ecover laundry powder is 100% sodium percarbonate, so that might benefit by some washing soda. It is a good idea to add a dash of washing up liquid to these to act as a wetting agent to prevent the beading or globules that form on hard surfaces, like water behaves on a polished car. You need a smooth film to form on your equipment if you are 'washing' with a cloth, but probably not so important if you are completely immersing. Some products will already have surfactants in them, but the oxi products does not seem to have them - certainly the cheaper ones.

The proprietary home-brew cleaners/sterilisers, at least those that are based on sodium metasilicate or trisodium phosphate, are probably better cleaners than the domestic products for stubborn deposits.

I am surprised that bleach does not work for whatever it is that you are trying to shift; the caustic soda in bleach should make it uber powerful.

It is okay to use other domestic products as long as you rinse well; although washing powder does not seem to be as effective as percarbonate, in my tea-cup experiments at least.

I don't own a dishwasher, but it does occur to me that dishwasher powder must be quite powerful. Next time I am in a supermarket, I'll have a look to see what the active ingredients are - if I remember that is - I have been meaning to do this for ages.

[Kev888]

Thanks Graham, thats excellent. It is indeed the ecover stuff I was using - possibly not as cheap as some of the budget oxy cleaners but as you say 100% percarbonate. I'll try mixing in some soda crystals and a dash of washing up liquid next time and see what happens.

Yes I've always liked the proprietary cleaners, they're just not available at especially reasonable prices locally so I tend to fall back on them rather than use routinely. Bleach is my normal cleaner, but it sometimes needs a bit of a scrub as well as the rinse, whereas percarbonate and to some degree soda crystals seem a bit more effective where scrubbing is difficult. Its perhaps also partially because (rightly or wrongly) I'm happier to leave things like stainless dip tubes soaking for longer in them than I am in bleach.

I'm just looking at my dishwasher powder (Sainbury's own brand). It details the composition as >30% Phosphates, 5%-15% 'oxygen based bleaching agent' and <5% non-ionic surfacants, and 'contains enzymes and perfume'. Pity that its perfumed, but otherwise looks like it has potential too - I'll have to give it a go at some point and see how it compares with a percarbonate/soda crystal mix.

Cheers
Kev

[Graham]

Thanks Graham, thats excellent. It is indeed the ecover stuff I was using - possibly not as cheap as some of the budget oxy cleaners but as you say 100% percarbonate.

Yes, but Ecover is three times as strong as the cheap Oxi stuff, which offsets the cost.

I'm just looking at my dishwasher powder (Sainbury's own brand). It details the composition as >30% Phosphates, 5%-15% 'oxygen based bleaching agent' and <5% non-ionic surfacants, and 'contains enzymes and perfume'. Pity that its perfumed, but otherwise looks like it has potential too - I'll have to give it a go at some point and see how it compares with a percarbonate/soda crystal mix.

Pity they do not specify what the phosphates are. There are two reasons for including phosphates: Something like trisodium phosphate is a powerful cleaner, but another type of phosphate (like Calgon) is used to sequester the calcium in hard water so that it does not form chalk and cause streaking or a white film on glass, or, of course, coat your element. The sequester will certainly be there, but whether the cleaner type is there is not clear. The 'oxygen based bleaching agent' is sodium percarbonate of course.

[Kev888]

Thats useful, thanks - I didn't realise what the phosphates were in the dishwasher powder.

Its just the brand I happen to have, but this particular dishwasher powder would work out as a little over £2 per kg, which by their figures would include >300g of phosphates and 50g-150g of percarbonate, whilst for a similar cost the ecover stuff is a guaranteed 400g of percarbonate.

I guess the lack of detail on the phosphates and the wide possible range for percarbonate quantity makes this a little difficult to judge. But you could envisage with decent ratios the phosphate/percarbonate mix would be more effective than the soda-crystal/percarbonate one I was thinking of - and still available locally. Think I'll check some more labels next time I'm shopping.

Cheers
kev