Potassium metabisulfite Strength

[silverbullet07]

Are some Potassium metabisulfite strengths different. Most instructions I see say 1/4 tsp per 6 gal. I picked up some and the brand is Brewcraft. It says 1/2 tsp for 6 gals of wine. Was going to add some to my wine after fermentation to age.

 

[Johnd]

I've not run into different strengths of the powder, but that doesn't mean that they are not out there. Maybe someone else has run into this issue before and will chime in.

Does it say what PPM you will achieve by using the 1/2 tsp / 6 gallons???

 

[silverbullet07]

No it does not. When I visit their website the instructions say 1/4 tsp per 6 gal. Funny the package says 1/2 tsp per 6. I am just going to go by the recommended 1/4 tsp for 5 gal. Better safe than sorry.

 

[Johnd]

No it does not. When I visit their website the instructions say 1/4 tsp per 6 gal. Funny the package says 1/2 tsp per 6. I am just going to go by the recommended 1/4 tsp for 5 gal. Better safe than sorry.

That's odd that the directions would be different in those two places. If you have the capability, test your wine after the 1/4 tsp per 6 gallon addition and see where the sulfite clocks in at, then you'll know how to dose down the line.

 

[silverbullet07]

That is what I thought to. I do not have a way to check at this time since I am just beginning. I guess that will be next on my list for next year.

 

[Rice_Guy]

Potassium metabisulphite is a dry white chemical powder.

anything labeled potassium metabisulphite in the US legally should be 100% chemical. If there is another name as “quick dissolving potassium metabisulphite “ it will have other ingredients that produce that function and should have packaging to give percentage.

Outside the US can be another story. Europe is better at divulging ingredients/ process aids than the US

 

[E-man]

I've been using the same brand of Brewcraft SO2 and often wondered the same but have ultimately split the difference. Their package also only mentions the addition of the 1/2 tsp prior to bottling, nothing about pre-fermentation addition to kill of wild yeast or maintenance levels after fermentation while bulk aging. Maybe they are assuming quick bottling after fermentation with just one large addition prior to bottling?

 

[Rice_Guy]

My recommendation is to have a protective level anytime alcohol and oxygen are in the system, (if you run a DO meter you can measure/ otherwise it is prophylactic) ,,,
ie raw juice does not have the risk factors

I would ignore variable package directions in preference to keeping 50 ppm SO2 at any time you are opening the carboy for a manipulation. ,,,, ? If you run SO2 then use a calculator, ,,,, otherwise oxygen is everywhere we habit therefore assume zero residual SO2

 

[stickman]

I also get the feeling that the 1/2tsp assumes one large addition after fermentation, similar to the directions with a kit. I agree with @Rice_Guy that the powder should be comercially pure which would be close to 100% potassium metabisulfite or 57% SO2 by weight. Volume measurements can vary in weight to some extent, so I prefer using a scale, but there is enough experience to indicate that volume measurements will suffice with the standard commercial material. To me, labeling the product like that is a recipe for disaster for a beginner winemaker.