potassium metabisulphite & sodium of that ilk

[ToulouseLePlot]

The Selection instructions say: " if you want to age more than 6 months add 1.5 gm (1/4 tsp) potassium metabisulphite" (to a 30 bottle kit). Wikipedia (sorry) says potassium metabisulphite and sodium metabisulphite are pretty interchangeable. My Richies campden tablet powder (sodium metabisulphite) says one teaspoon is the equivalent of 1 campden tablet and so you need 5 for a 30 bottle kit.

So I have a couple of questions for you, I'm sorry if they are a bit basic and you think 'oh that one again', but typing sulphite into the search engine kicked up 20 pages of references...

For my present stock of campden powder (Richies) should I dose a 30 bottle kit with 5tsp or 1/4tsp to protect it for more than 6 month in the bottle?
If I'm going to do this fairly regularly, is there a better supply of potassium metabisulphite... Campden powder looks pretty outrageously extravagant if 1/4tsp = 5tsp (do they cut it with chalk or something?)
My friendly LHBS says potassium is a US tradition, whereas UK run with sodium, if you've got the patience to explain maybe you could suggest what the difference is and why one might be preferable?

Your help will be really useful and your patience in finding the time to answer very much appreciated.

[Cellar_Rat]

"potassium metabisulphite and sodium metabisulphite are pretty interchangeable" technically yes - in wine ABSOLUTELY NOT.
Pot met makes the difference (in taste) IMO between homebrew and Amateur winemaking. Commercial Vineyards ONLY use use Sod met for cleaning ('cos its much cheaper)

HBS a bit wide of the make - try finding a Englisg commercial vineyard using Sod met in the wine - just not happening.

I buy Pot met powder and have drug dealer scales that do grams to 2 places decimal (£10 on ebay). I think Karl (duffbeer) does pot met powder - if not PM me.

Sulphiting is an ongoing task. It is about testing for level and adding what is necessary to balance depending on task in hand. Toooo big a subject for a quick post sorry.

Not sure that answers the question specifically, but is on topic

[goldseal]

The subject of difference in taste WILL stir it up on this forum .

(and ... .duck ....)

However, the campden tablet / powder / metabisulphite measurement question is easier to answer.

I'll use the term 'sulphite' to cover both potassium and sodium metabisulphite, to avoid offending anyone (and it's shorter to type ).

Campden tablets contain a small amount of sulphite, and a lot of bulking agent. Ditto campden powder. My calculator tells me that a campden tablet contains around 0.5g sulphite. That means a teaspoon of campden powder will contain around 0.5g too.

By buying campden tablets or powder you are buying mostly inert material, although it does make things easier to measure.

Sulphite is bought (more or less) pure, so 5g of sulphite powder contains 5g of sulphite.

Many people (maybe most people) on this Forum use 10% sulphite solution. For example:

Take 50g of sulphite of powder, dissolve it in water and make the volume up to 500ml. You now have a 10% solution.

I do this with small amounts of potassium metabisulphite for additions to wine, and with larger amounts in a spray bottle for sanitising. I do this because sodium is about half the price of potassium, but both are WAY cheaper than campden tablets/powder.

I use two squirts from a 2.5ml syringe to stabilise 1 gal of fermented wine - 5ml is equivalent to 1 campden tablet.

25ml of 10% sulphite solution will be sufficient for 5 gals / 23 litres.

I know of two HBSs which sell sulphite in 500g and 1kg bags:

www.hobbywinesupplies.co.uk - run by our very own Karl (duffbeer)

www.brewingathome.co.uk - also highly recommended.

By the way, sodium is around 10% 'stronger' than potassium, so technically you should probably make 11% potassium solution. I suppose it depends how accurate your measurements are. I invested in a set of gramme scales (accurate to 0.1g), but if you are mixing 50g of sulphite, something accurate to 1g would be OK.

I hope this helps

[Duffbeer]

also bare in mind that Ritchi's camden powder contains very little sulphite and is bulked up with 'powder' basicaly for ease of use, do not convert to 1 tsp of neat sulphite (potassium or sodium)or you will seriously overdose. So to answer your question yes one teaspoon of ritchi's campden powder per gall would be equivilent to a 5ml sulphite solution, which in my opinion x5 in your kit will be plenty for up to a couple to three of years storing.


Seems Pete beat me to it

[goldseal]

Seems Pete beat me to it

[ToulouseLePlot]

Whey Hey! As they say. - I've been trying to understand this bit for about a year. How very kind of you (all) to take the time to explain it - this is going to be a useful introduction to the video on testing I've earmarked to watch. You know it's not exactly helped by Richies not putting on their powders & pills the quantity of active ingredient. I assumed from the 1tsp/gal that it must be diluted in comparison with the chemical to which Winexpert instructions referred.

So those batches currently on the shelf with 1tsp:5gal will have to take their chances. I somehow doubt most of them will be asked to outlive Methuselah, at the moment a wine that survives it's 1st birthday is 'an oversight' though the whole plan is tomove more in this direction, so this information is really timely. Thank you very much.

[cpfan]

"potassium metabisulphite and sodium metabisulphite are pretty interchangeable" technically yes - in wine ABSOLUTELY NOT.
Pot met makes the difference (in taste) IMO between homebrew and Amateur winemaking. Commercial Vineyards ONLY use use Sod met for cleaning ('cos its much cheaper)

Wineries only use K-meta because of laws to that effect. Government health agencies blame Sodium (Na) on health issues, so Na-meta is not allowed in commercial wines.

Is there a taste difference? I don't think so, but I haven't done a proper taste test, so don't really know.

Steve

[NorthernWiner]

Both K and Na versions will accomplish the same goal. As has been pointed out, the sodium version is slightly stronger than the K-meta. It's also less expensive.

I live in the US, and commercial wineries here (and Canada, too, I believe) are only allowed by law to add potassium metabisulphite to wine. The odd thing is that I've seen plenty of domestic food products that list sodium meta amongst the ingredients, so I don't know the reason that it isn't allowed as a wine additive. I'm not sure health concerns are the only reason. Could perhaps be some sort of international trade agreement behind it, but that's only a guess. I've used both, and like cpfan says, I've never noticed a flavor difference.

We can also buy the powder here without any additives. Easier for calculations, I think.

[Cellar_Rat]

Many people (maybe most people) on this Forum use 10% sulphite solution. For example:

Take 50g of sulphite of powder, dissolve it in water and make the volume up to 500ml. You now have a 10% solution.

Good point. I do seem to be alone with my druggy scales!

[NorthernWiner]

Good point. I do seem to be alone with my druggy scales!

You're not alone. I use a gram scale to measure sulphite additions.

[Cellar_Rat]

Phew - Thanks Steve

[robwrx]

I too bought some gram scales for use at home after I was seen 'cutting' a large quantity of white powder on the very accurate scales at work. That took a bit of explaining

Sent from my HTC Desire using Tapatalk

[goldseal]

I had that thought: I spend a lot of time measuring white powder in large, tightly-wrapped plastic bags into little, zip-lock plastic bags.

I also help run a football supporter's club, so I regularly have people coming to the door, giving me cash in exchange for tickets.

Sooner or later, someone is going to notice both of these activities, put two and two together and make five ...

[Original Mac]

You're not alone. I use a gram scale to measure sulphite additions.

Yep me too. SWMBO invested in a set of Weightwatchers scales, something to do with calculating points values of various foodstuffs. As with most diets, interest was eventually lost which left a set of redundant scales. Only until I noticed they were gram scales that is. As they have a zero function, measuring directly into the spray bottle is a doddle. Very useful piece of kit.